CN102497557B - 2*2 code unit-based image compression method and 2*2 code unit-based image decompression method, and image compression and decompression system - Google Patents

Abstract

The invention provides a 2*2 code unit-based image compression method having a fixed compression ratio, wherein the method is used for carrying out coding on a 2*2 code unit in an image. The image compression method comprises: it is determined whether a 2*2 code unit is one of man-made types of from a first man-made type to a seventh man-made type; if so, it is determined that the 2*2 code unit is one of a man-made type; if not, it is determined that the 2*2 code unit is one of a natural type; difference error coding, quantification, and table look-up coding are carried out on the 2*2 code unit of the man-made type, thereby generating first coding data; or color gamut conversion is carried out on the 2*2 code unit of the natural type so as to obtain a 2*2 color gamut conversion unit and then discrete cosine transform is carried out on the 2*2 color gamut conversion unit so as to generate a 2*2 frequency domain unit; and quantification and table look-up coding are carried out on the 2*2 frequency domain unit, so that second coding data are generated.

Description

Image compression, decompression method and system based on 2x2 coding unit

Technical field

The invention belongs to image compression, decompression technique field, refer in particular to a kind of fixing compression ratio image compression, decompression method and system based on 2x2 coding unit.

Background technology

As everyone knows, harmless image compression technology can be divided into: running length (Run Length) coding, huffman coding (Huffman Coding), Lempel-Ziv-Weich coding, the coding that counts (Arithmetic Coding), differential coding (Differential Coding) and JPEG-LS coding (Lossless JPEG) etc.Wherein, Run Length coding is to change a succession of identical data into two bytes (Byte) to represent, the length (that is number of repetition) that previous byte (Byte) is this string data, after a byte (Byte) for record data.For example data are " 555555AA ", via becoming " 652A " after Run Length coding, wherein, indicate 6 " 5 ", 2 " A ", and this compress mode has just been saved the space of 4 bytes.But Run Length coding needs the repetition rate of statistics input data, in the time that the repetition rate of data is low, compression ratio also reduces.

Huffman coding is according to occurring that probability is used binary tree mode (Binary Tree) coding by input data, occur that the shorter code of symbol length that probability is large represents, the representation that the symbol that appearance probability is little uses length to grow, thereby its average data volume using is less, but, it is the same with Run Length coding, add up the probability that input data occurs.

Lempel-Ziv-Weich coding uses the character string that occurred as the table look-up foundation of comparison of index, and the mode of setting up index is as data compression crossfire.But Lempel-Ziv-Weich coding method need to be used large memory headroom, the form of being set up to keep in.

The maximum feature of coding (Arithmetic Coding) that counts is that it is not with one of a symbology, but represents squeezing characters string with a real number.This method need first read through original character string, add up each different character code and occur probability, 0 to 1 real number interval is divided into original coding interval table according to this probability, then the character of original character string is read in one by one, often read in a character, just its shared interval is cut apart with original coding interval table, after so running through to last character again, will produce between an area postrema, the more interval compressed file of choosing a real number and represent original character string from then on.The coding that the coding that counts obtains only needs the space of a storage floating number to deposit in, and without needing large quantity space to store as huffman coding, but its shortcoming is that the probability and the algorithm that need statistics input data to occur are very complicated.

Differential coding uses difference between discreet value and the actual value foundation as compression, and its while using separately compression ratio low.JPEG-LS coding uses discrete cosine transform and predictor error value as the foundation of compressing.

In aforementioned compression method, its compression ratio on-fixed, in the time decompressing, usually need more computational resource, correctly to obtain data length, simultaneously in an embedded system or handheld apparatus, because it only possesses limited computing capability and limited memory size, above-mentioned image compression technology is all difficult to use in embedded system or handheld apparatus.Hence one can see that, the space that image compression and decompressing function are still improved on embedded system or handheld apparatus.

Summary of the invention

Object of the present invention is mainly to provide a kind of fixing compression ratio image compression based on 2x2 coding unit, the method and system of decompression, to produce the image of fixing compression ratio, and reduces hsrdware requirements simultaneously and maintains the quality of image.

According to a characteristic of the present invention, the present invention proposes a kind of fixing compression ratio image compressing method based on 2x2 coding unit, its 2x2 coding unit by an image is encoded, this image has at least one 2x2 coding unit, this image compressing method comprises the following steps: that (A) receives a 2x2 coding unit, and it comprises the top left corner pixel, upper right corner pixel, lower left corner pixel and the lower right corner pixel that are matrix arrangement, (B) judge whether this 2x2 coding unit is in the artificial type of the first artificial type to the seven, if, judge the 2x2 coding unit that this 2x2 coding unit is artificial type, otherwise, 2x 2 coding units that fixed these 2x 2 coding units are natural type, wherein the first artificial type is these four pixels two horizontal stripes in horizontal direction, the second artificial type is two vertical stripes that these four pixels are vertical direction, the 3rd artificial type is the two slanted bar lines intersections that these four pixels are miter angle direction, the the 4th to the 7th artificial type is the combinations with single-point triangular in shape of these four pixels, (C) to being judged to be the 2x2 coding unit of the artificial type coding that carries out differential errors coding, quantizes and table look-up, to produce first coding data, (D) the 2x2 coding unit that is judged to be natural type is carried out to color gamut conversion, to obtain 2x2 gamut conversion unit, (E) described 2x2 gamut conversion unit is carried out to discrete cosine transform, to produce 2x2 frequency domain unit, and (F) described 2x2 frequency domain unit is quantized and the coding of tabling look-up, to produce the second coded data.

According to another characteristic of the present invention, the present invention proposes a kind of fixing compression ratio image decompression method based on 2x2 coding unit, the method is that the coding package of a fixed bit size is decoded, to produce a 2x2 decoding unit of an image, this 2x2 decoding unit comprises and is four pixels that matrix is arranged, this image has at least one 2x2 decoding unit, and this image decompression method comprises the following step: (A) receive a coding package; (B) according to main packet header (1 bit of this coding package, 1) judge whether this coding package is artificial type, if so, judge that this coding package is behaved to make the coding package of type, otherwise, judge the coding package that this coding package is natural type; (C) the coding package of this artificial type is carried out to inverse quantization, counter table look-up decoding and contrast point error decoding, to produce the first decoded data; (D) the coding package of this natural type is carried out to inverse quantization and the anti-decoding of tabling look-up, to produce the second decoded data; (E) this second decoded data is carried out to discrete cosine transform, to produce the 3rd decoded data; (F) the 3rd decoded data is carried out to color gamut conversion, to obtain the 4th decoded data; And (G) receive described the first decoded data or the 4th decoded data, and the first decoded data or the 4th decoded data are rebuild, to produce 2x2 decoding unit.

According to another characteristic of the present invention, the present invention proposes a kind of display system of the fixing compression ratio based on 2x2 coding unit, it is that a show image is compressed and decompressed, this display system comprises a display module, one image input equipment, one fixing compression ratio image compression device based on 2x2 coding unit, one apparatus for temporary storage, one fixing compression ratio image decompressing device based on 2x2 coding unit, and time schedule controller, be connected to this fixing compression ratio image decompressing device based on 2x2 coding unit, receive this 2x2 decoding unit, drive signal and show data to produce the sequential of this display module.This display module is used for showing an image.This image input equipment is used for inputting a show image.Should be connected to this image input equipment by the fixing compression ratio image compression device based on 2x2 coding unit, the 2x2 coding unit of this show image is encoded, to produce the coding package corresponding with this 2x2 coding unit, wherein, described image has at least one 2x2 coding unit.Described apparatus for temporary storage is connected to the fixing compression ratio image compression device based on 2x2 coding unit, to keep in the coding package of this fixing compression ratio image compression device output based on 2x2 coding unit.The described fixing compression ratio image decompressing device based on 2x2 coding unit is connected to apparatus for temporary storage, receives described coding package, and this coding package is decompressed, to produce the 2x2 decoding unit corresponding with this 2x2 coding unit.Described time schedule controller is connected to the fixing compression ratio image decompressing device based on 2x2 decoding unit, receives described 2x2 decoding unit, drives signal and shows data to produce the sequential of this display module.Wherein, described fixing compression ratio image compression device first judges that this 2x2 coding unit is artificial type or natural type, with the coding that carries out differential errors coding, quantizes and table look-up of the 2x2 coding unit to artificial type, and generation one first coding data, and to the 2x2 coding unit of the natural type coding that carries out color gamut conversion, discrete cosine transform, quantizes and table look-up, and then generation the second coded data, again this first coding data or this second coded data are encapsulated, to produce the coding package of fixing compression ratio.

Brief description of the drawings

Fig. 1 is the flow chart of a kind of fixing compression ratio image compressing method based on 2x2 coding unit of the present invention;

Fig. 2 is the schematic diagram of described image and 2x2 coding unit;

Fig. 3 is the schematic diagram of artificial type and natural type in the present invention;

Fig. 4 be 2x2 coding unit in embodiments of the invention one differential errors coding, quantize and the schematic diagram of the coding of tabling look-up;

Fig. 5 is coding schematic diagram when 2x2 coding unit is first, second and third artificial type in embodiments of the invention one;

Fig. 6 is that in embodiments of the invention one, 2x2 coding unit is the the 4th, the 5th, the 6th and coding schematic diagram when the 7th artificial type;

Fig. 7 is the schematic diagram of color gamut conversion and discrete cosine transform in the present invention;

In Fig. 8 the present invention, expand artificial type schematic diagram;

Fig. 9 is the differential errors coding of expanding artificial type in embodiment mono-, quantize and the schematic diagram of the coding of tabling look-up;

Figure 10 is the 2x2 coding unit of expanding artificial type in the embodiment mono-coding schematic diagram while being first, second and third artificial type;

Figure 11 is that the 2x2 coding unit of expanding artificial type in embodiment mono-is the 4th coding schematic diagram during to the 7th artificial type;

Figure 12 is that the 2x2 coding unit of expanding artificial type in embodiment mono-is the 8th coding schematic diagram during to 13 artificial type;

Figure 13 is the schematic diagram of the coding of natural type in embodiment mono-;

Figure 14 is the table lookup operation schematic diagram of natural type in embodiment mono-;

Figure 15 is the differential errors coding of expanding artificial type in embodiment bis-, quantize and the schematic diagram of the coding of tabling look-up;

Figure 16 is the 2x2 coding unit of expanding artificial type in the embodiment bis-coding schematic diagram while being first, second and third artificial type;

Figure 17 is that the 2x2 coding unit of expanding artificial type in embodiment bis-is the 4th coding schematic diagram during to the 7th artificial type;

Figure 18 is that the 2x2 coding unit of expanding artificial type in embodiment bis-is the 8th coding schematic diagram during to 13 artificial type;

Figure 19 is the schematic diagram of the coding of natural type in embodiment bis-;

Figure 20 is the table lookup operation schematic diagram of natural type in embodiment bis-;

Figure 21 is the flow chart of a kind of fixing compression ratio image decompression method based on 2x2 coding unit of the present invention;

Figure 22 is the structure chart of the display system of the fixing compression ratio of a kind of application of the present invention based on 2x2 coding unit.

In accompanying drawing, the parts of each label representative are as follows:

S110～S180, step,

210, image, 220,2x2 coding unit,

310, the first artificial type, 320, the second artificial type, 330, the 3rd artificial type, 340, the 4th artificial type, 350, the 5th artificial type, 360, Sixth Man makes type, 370, the 7th artificial type, 380, the first natural type, 390, the second nature type

700,2x2 gamut conversion unit, 710, lightness 2x2 gamut conversion unit, 720, the first colourity 2x2 gamut conversion unit, 730, the second colourity 2x2 gamut conversion unit, 750,2x2 frequency domain unit, 760, lightness 2x2 frequency domain unit, 770, the first colourity 2x2 frequency domain unit, 780, the second colourity 2x2 frequency domain unit

S805～S850, step,

900, display system, 910, display module, 920, image input equipment, 930, the fixing compression ratio image compression device based on 2x2 coding unit, 940, apparatus for temporary storage, 950, fixing compression ratio image decompressing device based on 2x2 coding unit, 960, time schedule controller, 970, source electrode driver, 980, gate drivers

Embodiment

For making object of the present invention, technical scheme and advantage clearer, referring to the accompanying drawing embodiment that develops simultaneously, the present invention is described in further detail.

Fig. 1 is the flow chart of a kind of fixing compression ratio image compressing method based on 2x2 coding unit of the present invention, and it is that a 2x2 coding unit in an image is encoded.

First, in step S110, this image compressing method receives a 2x2 coding unit, and this 2x2 coding unit comprises and is top left corner pixel, upper right corner pixel, lower left corner pixel and the lower right corner pixel that matrix is arranged.

Fig. 2 is the schematic diagram of this image and this 2x2 coding unit, as shown in Figure 2, this image 210 has at least one 2x2 coding unit 220, each 2x2 coding unit 220 has four pixel A, B, C, D, wherein, A is top left corner pixel, and B is upper right corner pixel, C is lower left corner pixel, and D is lower right corner pixel.Each pixel has red (r), blue (g), green (b) three kinds of colors, wherein A _r, A _g, A _bfor the red value of pixel A, green numerical value, blue values, B _r, B _g, B _bfor the red value of pixel B, green numerical value, blue values, C _r, C _g, C _bfor the red value of pixel C, green numerical value, blue values, D _r, D _g, D _bfor the red value of pixel D, green numerical value, blue values.Can select every kind of color numerical value is 8, therefore this 2x2 coding unit 220 is 96 (=4 × 3 × 8) position.Also can select every kind of color numerical value is 6, therefore this 2x2 coding unit 220 is 72 (=6 × 3 × 4) position.

In step S120, judge whether this 2x2 coding unit 220 is artificial type, if, judge the 2x2 coding unit that this 2x2 coding unit is artificial type, otherwise, judge the 2x2 coding unit that this 2x2 coding unit is natural type, wherein, artificial moulding has seven kinds, comprising: the first artificial type: four pixels, two horizontal stripes in horizontal direction; The second artificial type: four pixels are two vertical stripes of vertical direction; The 3rd artificial type: four pixels are two slanted bar lines intersections of miter angle direction; The the 4th to the 7th artificial type: four pixels combination with single-point triangular in shape.

Illustrate further, in step S120, be first to judge whether this 2x2 coding unit 220 is in the artificial type of the first artificial type to the three, then judge whether this 2x2 coding unit 220 is in the artificial type of the 4th artificial type to the seven.

Fig. 3 is the schematic diagram of the artificial type of the present invention and natural type.The classification of artificial type to the seven artificial types of the present invention first contributes to process as certain patterns such as font edge, gray scale variation, sawtooth, gridiron patterns, coordinates package recording mode of the present invention, can make those coding units reach undistorted.

As shown in Figure 3, the first artificial type 310 is described four pixels two horizontal stripes in horizontal direction, be that the color numerical value (X) of pixel A is identical or approximate with the color numerical value (X) of pixel B, the color numerical value (Y) of pixel C is identical or approximate with the color numerical value (Y) of pixel D.In like manner, the second artificial type 320 is two vertical stripes that described four pixels are vertical direction, the 3rd artificial type 330 is intersected for the two slanted bar lines that described four pixels are miter angle direction, and the 4th artificial type 340, the 5th artificial type 350, Sixth Man are made type 360 and the combination with single-point triangular in shape for described four pixels of the 7th artificial type 370.That is: the first artificial type 310 is described top left corner pixel and upper right corner pixel approximate (X) and lower left corner pixel and lower right corner pixel approximate (Y); The second artificial type 320 is described top left corner pixel and lower left corner pixel approximate (X) and upper right corner pixel and lower right corner pixel approximate (Y); The 3rd artificial type 330 is described top left corner pixel and lower right corner pixel approximate (X) and lower left corner pixel and upper right corner pixel approximate (Y); The 4th artificial type 340 is described lower left corner pixel, upper right corner pixel and lower right corner pixel approximate (Y); The 5th artificial type 350 is described top left corner pixel, upper right corner pixel and lower right corner pixel approximate (Y); Sixth Man is made type 360 for described top left corner pixel, lower left corner pixel and upper right corner pixel approximate (Y); The 7th artificial type 370 is described top left corner pixel, lower left corner pixel and lower right corner pixel approximate (Y).

In step S120, in the time meeting following formula, judge that this 2x2 coding unit 220 is as the first artificial type 310:

ABS(A _r，B _r)＜THD1，ABS(C _r，D _r)＜THD1，

ABS(A _g，B _g)＜THD1，ABS(C _g，D _g)＜THD1，

ABS(A _b，B _b)＜THD1，ABS(C _b，D _b)＜THD1，

ABS(A _r，B _r)+ABS(A _g，B _g)+ABS(A _b，B _b)≤

ABS(A _r，C _r)+ABS(A _g，C _g)+ABS(A _b，C _b)，

ABS(A _r，B _r)+ABS(A _g，B _g)+ABS(A _b，B _b)≤

ABS(D _r，B _r)+ABS(D _g，B _g)+ABS(D _b，B _b)，

ABS(C _r，D _r)+ABS(C _g，D _g)+ABS(C _b，D _b)≤

ABS(D _r，B _r)+ABS(D _g，B _g)+ABS(D _b，B _b)，

ABS(C _r，D _r)+ABS(C _g，D _g)+ABS(C _b，D _b)≤

ABS(A _r，C _r)+ABS(A _g，C _g)+ABS(A _b，C _b)，

Wherein, THD1 is the first threshold value (its value is rule of thumb chosen by those skilled in the art), and A is described top left corner pixel, and B is described upper right corner pixel, and C is described lower left corner pixel, and D is described lower right corner pixel, A _r, A _g, A _bbe respectively the red value of pixel A, green numerical value and blue values, B _r, B _g, B _bbe respectively the red value of pixel B, green numerical value and blue values, C _r, C _g, C _bbe respectively the red value of pixel C, green numerical value and blue values, D _r, D _g, D _bbe respectively the red value of pixel D, green numerical value and blue values.Wherein ABS is the poor ABS function of two elements in bracket, that is in the time of a >=b, ABS (a, b)=a-b, in the time of a < b, ABS (b, a)=b-a.

In step S120, in the time meeting following formula, judge that this 2x2 coding unit 220 is as the second artificial type 320:

ABS(A _r，C _r)＜THD1，ABS(B _r，D _r)＜THD1，

ABS(A _g，C _g)＜THD1，ABS(B _g，D _g)＜THD1，

ABS(A _b，C _b)＜THD1，ABS(B _b，D _b)＜THD1，

ABS(A _r，C _r)+ABS(A _g，C _g)+ABS(A _b，C _b)≤

ABS(A _r，B _r)+ABS(A _g，B _g)+ABS(A _b，B _b)，

ABS(A _r，C _r)+ABS(A _g，C _g)+ABS(A _b，C _b)≤

ABS(D _r，C _r)+ABS(D _g，C _g)+ABS(D _b，C _b)，

ABS(B _r，D _r)+ABS(B _g，D _g)+ABS(B _b，D _b)≤

ABS(D _r，C _r)+ABS(D _g，C _g)+ABS(D _b，C _b)，

ABS(B _r，D _r)+ABS(B _g，D _g)+ABS(B _b，D _b)≤

ABS(A _r，B _r)+ABS(A _g，B _g)+ABS(A _b，B _b)。

In step S120, in the time meeting following formula, judge that this 2x2 coding unit 220 is as the 3rd artificial type 330:

ABS(A _r，D _r)＜THD1，ABS(C _r，B _r)＜THD1，

ABS(A _g，D _g)＜THD1，ABS(C _g，B _g)＜THD1，

ABS(A _b，D _b)＜THD1，ABS(C _b，B _b)＜THD1，

ABS(A _r，D _r)+ABS(A _g，D _g)+ABS(A _b，D _b)≤

ABS(A _r，B _r)+ABS(A _g，B _g)+ABS(A _b，B _b)，

ABS(A _r，D _r)+ABS(A _g，D _g)+ABS(A _b，D _b)≤

ABS(D _r，C _r)+ABS(D _g，C _g)+ABS(D _b，C _b)，

ABS(C _r，B _r)+ABS(C _g，B _g)+ABS(C _b，B _b)≤

ABS(D _r，C _r)+ABS(D _g，C _g)+ABS(D _b，C _b)，

ABS(C _r，B _r)+ABS(C _g，B _g)+ABS(C _b，B _b)≤

ABS(A _r，B _r)+ABS(A _g，B _g)+ABS(A _b，B _b)。

In step S120, in the time meeting following formula, judge that this 2x2 coding unit 220 is as the 4th artificial type 340:

ABS(B _r，D _r)＜THD2，ABS(C _r，D _r)＜THD2，

ABS(B _g，D _g)＜THD2，ABS(C _g，D _g)＜THD2，

ABS(B _b，D _b)＜THD2，ABS(C _b，D _b)＜THD2，

ABS(B _r，D _r)+ABS(B _g，D _g)+ABS(B _b，D _b)≤

ABS(A _r，C _r)+ABS(A _g，C _g)+ABS(A _b，C _b)，

ABS(B _r，D _r)+ABS(B _g，D _g)+ABS(B _b，D _b)≤

ABS(A _r，B _r)+ABS(A _g，B _g)+ABS(A _b，B _b)，

ABS(C _r，D _r)+ABS(C _g，D _g)+ABS(C _b，D _b)≤

ABS(A _r，B _r)+ABS(A _g，B _g)+ABS(A _b，B _b)，

ABS(C _r，D _r)+ABS(C _g，D _g)+ABS(C _b，D _b)≤

ABS(A _r，C _r)+ABS(A _g，C _g)+ABS(A _b，C _b)。

Wherein, THD2 is the second threshold value (its value is rule of thumb chosen by those skilled in the art),

In step S120, in the time meeting following formula, judge that this 2x2 coding unit 220 is as the 5th artificial type 350:

ABS(B _r，D _r)＜THD2，ABS(A _r，B _r)＜THD2，

ABS(B _g，D _g)＜THD2，ABS(A _g，B _g)＜THD2，

ABS(B _b，D _b)＜THD2，ABS(A _b，B _b)＜THD2，

ABS(B _r，D _r)+ABS(B _g，D _g)+ABS(B _b，D _b)≤

ABS(A _r，C _r)+ABS(A _g，C _g)+ABS(A _b，C _b)，

ABS(B _r，D _r)+ABS(B _g，D _g)+ABS(B _b，D _b)≤

ABS(C _r，D _r)+ABS(C _g，D _g)+ABS(C _b，D _b)，

ABS(A _r，B _r)+ABS(A _g，B _g)+ABS(A _b，B _b)≤

ABS(C _r，D _r)+ABS(C _g，D _g)+ABS(C _b，D _b)，

ABS(A _r，B _r)+ABS(A _g，B _g)+ABS(A _b，B _b)≤

ABS(A _r，C _r)+ABS(A _g，C _g)+ABS(A _b，C _b)。

In step S120, in the time meeting following formula, judge that this 2x2 coding unit 220 makes type 360 as Sixth Man:

ABS(A _r，C _r)＜THD2，ABS(A _r，B _r)＜THD2，

ABS(A _g，C _g)＜THD2，ABS(A _g，B _g)＜THD2，

ABS(A _b，C _b)＜THD2，ABS(A _b，B _b)＜THD2，

ABS(A _r，C _r)+ABS(A _g，C _g)+ABS(A _b，C _b)≤

ABS(B _r，D _r)+ABS(B _g，D _g)+ABS(B _b，D _b)，

ABS(A _r，C _r)+ABS(A _g，C _g)+ABS(A _b，C _b)≤

ABS(C _r，D _r)+ABS(C _g，D _g)+ABS(C _b，D _b)，

ABS(A _r，B _r)+ABS(A _g，B _g)+ABS(A _b，B _b)≤

ABS(C _r，D _r)+ABS(C _g，D _g)+ABS(C _b，D _b)，

ABS(A _r，B _r)+ABS(A _g，B _g)+ABS(A _b，B _b)≤

ABS(B _r，D _r)+ABS(B _g，D _g)+ABS(B _b，D _b)。

In step S120, in the time meeting following formula, judge that this 2x2 coding unit 220 is as the 7th artificial type 370:

ABS(A _r，C _r)＜THD2，ABS(C _r，D _r)＜THD2，

ABS(A _g，C _g)＜THD2，ABS(C _g，D _g)＜THD2，

ABS(A _b，C _b)＜THD2，ABS(C _b，D _b)＜THD2，

ABS(A _r，C _r)+ABS(A _g，C _g)+ABS(A _b，C _b)≤

ABS(B _r，D _r)+ABS(B _g，D _g)+ABS(B _b，D _b)，

ABS(A _r，C _r)+ABS(A _g，C _g)+ABS(A _b，C _b)≤

ABS(A _r，B _r)+ABS(A _g，B _g)+ABS(A _b，B _b)，

ABS(C _r，D _r)+ABS(C _g，D _y)+ABS(C _b，D _b)≤

ABS(A _r，B _r)+ABS(A _g，B _g)+ABS(A _b，B _b)，

ABS(C _r，D _r)+ABS(C _g，D _y)+ABS(C _b，D _b)≤

ABS(B _r，D _r)+ABS(B _g，D _g)+ABS(B _b，D _b)。

In step S130, to the 2x2 coding unit of this artificial type coding that carries out differential errors coding, quantizes and table look-up, to produce first coding data.

Below respectively with regard in 2x2 coding unit, red (r) of each pixel, blue (g), green (b) three kinds of colors adopt 8 and 6 two specific embodiments that record to be specifically introduced image compressing method of the present invention respectively.

Embodiment mono-: in 2x2 coding unit, red (r) of each pixel, blue (g), green (b) three kinds of colors all adopt 8 to carry out record, therefore this 2x2 coding unit 220 is 96 (=4 × 3 × 8) position.

Fig. 4 be the 2x2 coding unit of embodiments of the invention one differential errors coding, quantize and the schematic diagram of the coding of tabling look-up, this embodiment mono-is the embodiment that in the 2x2 coding unit 220 in Fig. 2, each color numerical value adopts 8 bit representations, and this 2x2 coding unit 220 is 96 (=4 × 3 × 8) position.In Fig. 4, numeral figure place, for example 8,7 represent respectively 8 and 7.Oblique line represents table lookup operation, and backslash represents quantization operation.

In step S130, in the time that this 2x2 coding unit 220 is in the first artificial type 310, the second artificial type 320 and the 3rd artificial type 330, use the wherein mean value of two pixels of 8 records, use 7 record one 7 bit table cases to put, the content that records that this 7 bit table case is put is: all of these 7 bit table lattice record in content, and the difference of the mean value of two pixels that record with mean value and 8 of the aforesaid uses of other two pixels in this 2x2 coding unit differs reckling.This form is variable form, at any time a capable of regulating.One has four forms: 7 bit table lattice, 4 bit table lattice, 3 bit table lattice, 2 bit table lattice, and basic spirit: occur that the numerical value that probability is large is based upon in form, therefore easily out selected.Otherwise occur that the numerical value that probability is little gives up, be not based upon in form, because the resource-constrained (size of form is limited) storing.Embodiment provided by the present invention is only one of setting method of wherein certain form.In fact looking after and guiding the content of this form and product actual table, is follow-up optimized action.

The first artificial type 310, the second artificial type 320 and the 3rd artificial type 330 are lines form, therefore using the first artificial type 310 as explanation, the second artificial type 320 and the 3rd artificial type 330 are that the personnel for knowing this technology can complete based on the technology of the present invention, repeat no more.

Fig. 5 is the coding schematic diagram of the 2x2 coding unit of embodiments of the invention one while being the first artificial type, the second artificial type and the 3rd artificial type, this embodiment mono-is the embodiment that in the 2x2 coding unit 220 in Fig. 2, each color numerical value adopts 8 bit representations, and this 2x2 coding unit 220 is 96 (=4 × 3 × 8) position.It can be red, blue or green, is first the color numerical value (127) of pixel A and the color numerical value (126) of pixel B to be added again divided by 2 (126.5), then the acquisition 127 that rounds up, and uses 8 and records numerical value 127.

The color numerical value (34) of pixel C and the color numerical value (32) of pixel D are added again divided by 2 (33), round up again and obtain 33, deduct the numerical value 127 of previous calculating gained, to obtain-94, although the result of subtracting each other is 9, but the present invention uses one 7 bit table lattice to table look-up, can reduce the data volume producing after coding.Table look-up according to-94 pairs of one 7 bit table lattice.The-94th, between-95 and-90, and close-95, therefore obtain-95 position via after tabling look-up, use the position of 7 record-95.

In this form of 7, record altogether 128 values.If-95 approach j value of form most, record " j "." j " value can be calculated according to following formula:

[a ₁，a ₂，a ₃，...，a _k-2，a _k-1，a _k]，

sign[α-a _j]×sign[a _j+1-α]≥0， (1)

Wherein a ₁～a _kfor 128 values that record altogether in this form of 7, it is sequentially arranged from small to large.Sign is the function of the sign of this value of output, and α is the value of wanting to table look-up, and once meet formula (1), stores j value.

In step S130, when this 2x2 coding unit 220 is that the 4th artificial type 340, the 5th artificial type 350, Sixth Man are while making in type 360 and the 7th artificial type 370, use the wherein mean value of three pixels of 8 records, use 7 or 6 quantized values that record these 2x2 coding unit 220 another one pixels.

The 4th artificial type 340, the 5th artificial type 350, Sixth Man are made type 360 and the 7th artificial type 370 and are the combination of triangle and single-point, therefore describe as an example of the 4th artificial type 340 example, it is that personnel for knowing this technology can complete based on the technology of the present invention that the 5th artificial type 350, Sixth Man are made type 360 and the 7th artificial type 370, repeats no more.

Fig. 6 is that the 2x2 coding unit of embodiments of the invention one is the 4th artificial type 340, the 5th artificial type 350, the Sixth Man coding schematic diagram while making type 360 and the 7th artificial type 370, this embodiment mono-is the embodiment that in the 2x2 coding unit 220 in Fig. 2, each color numerical value adopts 8 bit representations, and this 2x2 coding unit 220 is 96 (=4 × 3 × 8) position.It can be redness, blueness or green.It is first added the color numerical value (100) of the color numerical value (100) of the color numerical value (100) of pixel B, pixel C and pixel D to obtain 100 divided by 3 again, then the acquisition 100 that rounds up, and uses 8 and records numerical value 100.

The color numerical value (34) of pixel A is carried out to quantization operations, then the fractional part acquisition numerical value 9 that rounds up, use 6 and record numerical value 9.In the time that the color of pixel A is green, uses 7 and record numerical value 9.This quantization operations is calculated by following formula:

$x_Q=\mathrm{Round}\left(\frac{x}{Q}\right)$

Wherein Q is a quantizing factor, and Round is the function that rounds up.In the time using 6 to record, quantizing factor Q is 4, and in the time using 7 to record, quantizing factor Q is 2.

When in step S120, while judging this 2x2 coding unit 220 not as in the artificial type of the first artificial type to the seven one, represent that this 2x2 coding unit 220 is natural type, therefore in step S140,2x2 coding unit 220 to this natural type carries out color gamut conversion, to obtain a 2x2 gamut conversion unit.

In step S140, by carrying out RGB to YUV color gamut conversion, to obtain 2x2 gamut conversion unit, this RGB to YUV color gamut conversion is undertaken by following formula:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1..& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r represents the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness (Luminance, Luma) that Y is this pixel, the colourity (Chrominance) that U and V are this pixel.Fig. 7 is the schematic diagram of color gamut conversion of the present invention and discrete cosine transform, as shown in Figure 7, this 2x2 gamut conversion unit 700 is to be respectively lightness 2x2 gamut conversion unit 710, the first colourity 2x2 gamut conversion unit 720 and the second colourity 2x2 gamut conversion unit 730.

The scope of the value of the element in this lightness 2x2 gamut conversion unit 710 is 0～255, the scope of the value of the element of this first colourity 2x2 gamut conversion unit 720 and the second colourity 2x2 gamut conversion unit 730 is-255～255, therefore the element of this lightness 2x2 gamut conversion unit 710 is 8, the element of this first colourity 2x2 gamut conversion unit 720 and the second colourity 2x2 gamut conversion unit 730 is 9, and this is only computational process, do not affect the position counting of last coding.Carrying out before next step S150, need first the value of the element of this lightness 2x2 gamut conversion unit 710 to be displaced to-128～127 by 0～255.

In step S150, this 2x2 gamut conversion unit 700 is carried out to discrete cosine transform, to produce a 2x2 frequency domain unit.

In step S150, this discrete cosine transform is undertaken by following formula:

$\left[\begin{array}{c}E\\ F\\ G\\ H\end{array}\right]=0.25\&times;\left[\begin{array}{cccc}1& 1& 1& 1\\ 1& -1& 1& -1\\ 1& 1& -1& -1\\ 1& -1& -1& 1\end{array}\right]\left[\begin{array}{c}\stackrel{\&OverBar;}{A}\\ \stackrel{\&OverBar;}{B}\\ \stackrel{\&OverBar;}{C}\\ \stackrel{\&OverBar;}{D}\end{array}\right],---\left(2\right)$

Wherein, for the upper left corner value of this 2x2 gamut conversion unit 700, for the upper right corner value of this 2x2 gamut conversion unit 700, for the lower left corner value of this 2x2 gamut conversion unit 700, for the lower right corner value of this 2x2 gamut conversion unit 700, E element is the upper left corner value of this 2x2 frequency domain unit 750, F element is the upper right corner value of this 2x2 frequency domain unit 750, G element is the lower left corner value of this 2x2 frequency domain unit 750, H element is the lower right corner value of this 2x2 frequency domain unit 750, and this 2x2 frequency domain unit 750 is divided into lightness 2x2 frequency domain unit 760, the first colourity 2x2 frequency domain unit 770 and the second colourity 2x2 frequency domain unit 780.

The scope of the value of the each element in this lightness 2x2 frequency domain unit 760 is-128～127, the scope of the value of each element of this first colourity 2x2 frequency domain unit 770 and the second colourity 2x2 frequency domain unit 780 is-255～255, therefore each element of this lightness 2x2 frequency domain unit 760 is 8, each element of this first colourity 2x2 frequency domain unit 770 and the second colourity 2x2 frequency domain unit 780 is 9, and this is only computational process, do not affect the position counting of last coding.

Transition matrix in formula (2) can be obtained by 2-D discrete cosine conversion, and formula (3) is a 2-D discrete cosine conversion formula:

$F(u,v)=\frac{1}{\sqrt{2N}}c\left(u\right)c\left(v\right)\underset{x=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\underset{y=0}{\overset{N-1}{\mathrm{\&Sigma;}}}f(x,y)\cos \left(\frac{(2x+1)\mathrm{u\&pi;}}{2N}\right)\cos \left(\frac{(2y+1)\mathrm{v\&pi;}}{2N}\right),---\left(3\right)$

Wherein,

Wherein, u, v are discrete frequency variable (discrete frequency variables), and the value of u, v is 0,1,2 ..., N-1, f (x, y) is N × N image pixel, F (u, v) result of changing for 2-D discrete cosine, in this embodiment, N is 2, can obtain the transition matrix in formula (2).

In step S160, this 2x2 frequency domain unit 750 is categorized as to the first natural type 380 or the second nature type 390, wherein, when F element and the G element of this first colourity 2x2 frequency domain unit 770 meet following formula:

max(ABS(F，0)，ABS(G，0))≤THD3，

And F element and the G element of the second colourity 2x2 frequency domain unit 780 meet following formula:

max(ABS(F，0)，ABS(G，0))≤THD4，

Judge that this 2x2 frequency domain unit 750 is as the first natural type 380, otherwise, judge that this 2x2 frequency domain unit 750 is the second nature type 390, wherein, THD3 is the 3rd threshold value, THD4 is the 4th threshold value (value of the 3rd threshold value and the 4th threshold value is rule of thumb chosen by those skilled in the art), and the 4th threshold T HD4 is greater than the 3rd threshold T HD3.

In step S170, this 2x2 frequency domain unit 750 is quantized and the coding of tabling look-up, to produce the second coded data.

In step S170, in the time that this 2x2 frequency domain unit 750 is the first natural type 380, use 7 E element, F element, G elements that record this lightness 2x2 frequency domain unit 760; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the difference reckling of the value of the H element of this lightness 2x2 frequency domain unit 760.

The value of the element of this lightness 2x2 frequency domain unit 760 is-128～127, thus need first carry out shift operation, so that the value of the element of this lightness 2x2 frequency domain unit 760 is displaced to 0～255 by-128～127.In step S170, be that the numerical value of E element, F element, G element is carried out to quantization operations, round up for fractional part, re-use 7 records.Because the numerical value of the E element of this lightness 2x2 frequency domain unit 760, F element, G element is 8, in the time using 7 to record, therefore quantizing factor Q is 2.The H element of this lightness 2x2 frequency domain unit 760 uses one 4 bit table lattice to carry out table lookup operation, and it is identical that the principle of this table lookup operation and aforementioned 7 bit table lattice are tabled look-up, and repeats no more.

In step S170, in the time that this 2x2 frequency domain unit 750 is the first natural type 380, use 7 E elements that record this first colourity 2x2 frequency domain unit 770; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the F element of this first colourity 2x2 frequency domain unit 770 and the mean value of G element; Do not record the H element of this first colourity 2x2 frequency domain unit 770.

The value of the element of this first colourity 2x2 frequency domain unit 770 is-255～255, thus need first carry out a shift operation, so that the value of the element of this first colourity 2x2 frequency domain unit 770 is displaced to 0～510 by-255～255.Therefore the element of this first colourity 2x2 frequency domain unit 770 is 9, in the time that the E element of this first colourity 2x2 frequency domain unit 770 is recorded in 7 of uses, need first carry out quantization operations, and wherein, quantizing factor Q is 4.

It is that F element and the G element of this first colourity 2x2 frequency domain unit 770 are first averaged, then one 2 bit table lattice is tabled look-up with this mean value, and it is identical that the principle of this table lookup operation and aforementioned 7 bit table lattice are tabled look-up, and repeats no more.

In step S170, in the time that this 2x2 frequency domain unit 750 is the first natural type 380, use 7 values that record the E element of this second colourity 2x2 frequency domain unit 780; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the mean value of F element in this second colourity 2x2 frequency domain unit 780 and G element; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the H element of this second colourity 2x2 frequency domain unit 780.

The value of the element of this second colourity 2x2 frequency domain unit 780 is-255～255, thus need first carry out a shift operation, so that the value of the element of this second colourity 2x2 frequency domain unit 780 is displaced to 0～510 by-255～255.Therefore the element of this second colourity 2x2 frequency domain unit 780 is 9, in the time that the E element of this second colourity 2x2 frequency domain unit 780 is recorded in 7 of uses, need first carry out quantization operations, and wherein, quantizing factor Q is 4.

It is that F element and the G element of this second colourity 2x2 frequency domain unit 780 are first averaged, then one 2 bit table lattice is tabled look-up with this mean value.It is identical that the principle that these 2 bit table lattice are tabled look-up and aforementioned 7 bit table lattice are tabled look-up, and repeats no more.

In step S170, in the time that this 2x2 frequency domain unit 750 is the second nature type 390, use 6 quantized values that record the E element of lightness 2x2 frequency domain unit 760, use 5 quantized values that record the F element of this lightness 2x2 frequency domain unit 760, use 5 quantized values that record the G element of lightness 2x2 frequency domain unit 760; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the H element of this lightness 2x2 frequency domain unit 760.This technical staff can learn according to the technology of the present invention in order to be familiar with for these quantizing factors Q and table lookup operation, repeats no more.

In step S170, in the time that this 2x2 frequency domain unit 750 is the second nature type 390, use 5 quantized values that record the E element of this first colourity 2x2 frequency domain unit 770; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the F element of this first colourity 2x2 frequency domain unit 770; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the G element of this first colourity 2x2 frequency domain unit 770; Do not record the H element of this first colourity 2x2 frequency domain unit 770.

In step S170, in the time that this 2x2 frequency domain unit 750 is the second nature type 390, use 5 quantized values that record the E element of this second colourity 2x2 frequency domain unit 780; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the value of the F element of this second colourity 2x2 frequency domain unit 780; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the value of the G element of this second colourity 2x2 frequency domain unit 780; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the H element of this second colourity 2x2 frequency domain unit 780.

In step S180, receive this first coding data or this second coded data, and this first coding data or this second coded data are encapsulated to (packaging), and then generate the coding package with fixed bit size.

As shown in Figure 4, step S180 uses 1 (main packet header) whether to record this 2x2 coding unit 220 as artificial type or natural type, re-use 2 (the first sub-packet header) to record whether in the first artificial type, the second artificial type, the 3rd artificial type or the 4th to the 7th artificial type of this 2x2 coding unit 220, finally use 2 (second son packet header) to record whether in the as the 4th to the 7th artificial type of this 2x2 coding unit 220.Therefore, in the time that this 2x2 coding unit 220 is in the first artificial type, the second artificial type, the 3rd artificial type, position after its coding and encapsulation is counted as 48 (=1+2+8+7+8+7+8+7), in the time that this 2x2 coding unit 220 is in the 4th to the 7th artificial type, the position counting after its coding and encapsulation is still 48 (=1+2+2+8+7+8+6+8+6).In the time that this 2x2 coding unit 220 is natural type, re-use 1 (the second sub-packet header) to record whether in the first natural type or the second nature type of this 2x2 coding unit 220, in the time that this 2x2 coding unit 220 is the first natural type, position counting after its coding and encapsulation is still 48 (=1+1+3 × 7+4+7+2+7+2+3), in the time that this 2x2 coding unit 220 is the second nature type, the position counting after its coding and encapsulation is still 48 (=1+1+6+5+5+3+5+3+3+5+4+4+3).

Figure 8 shows that the expansion of the artificial type in Fig. 3, this expansion expands to 17 kinds on the basis of seven kinds of above-mentioned artificial types.Wherein, the artificial type of the first artificial type to the seven is with above-mentioned consistent; Eight, the 9th artificial type, represents these four pixels horizontal stripe in horizontal direction and the combination of two single-points; Ten, the 11 artificial type, represents that these four pixels are the combination of a vertical stripe and two single-points of vertical direction; The the 12, the 13 artificial type, represents that these four pixels are a slanted bar line of miter angle direction and the combination of two single-points; The the 14 to the 17 artificial type is single channel type, refers to follow-up formulae express.

Corresponding above-mentioned 17 kinds of artificial types, the order that judges in step 120 is adjusted to some extent: first judge whether described 2x2 coding unit is in the 14 to the 17 artificial type, determine whether again in the artificial type of the first artificial type to the three, determine whether again in the artificial type of the 4th artificial type to the seven, then determine whether in the artificial type of the 8th artificial type to the 13.

Described the 8th artificial type, represents that described top left corner pixel and upper right corner pixel are similar to (L); Described the 9th artificial type, represents that described lower left corner pixel and lower right corner pixel are similar to (L); Described the tenth artificial type, represents that described top left corner pixel and lower left corner pixel are similar to (L); Described the 11 artificial type, represents that described upper right corner pixel and lower right corner pixel are similar to (L); Described the 12 artificial type, represents that described top left corner pixel and lower right corner pixel are similar to (L); Described the 13 artificial type, represents that described lower left corner pixel and upper right corner pixel are similar to (L).

According to 17 of above-mentioned new expansion kinds of artificial types, in step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 14 artificial type:

A _r＝A _g，A _g＝A _b

B _r＝B _g，B _g＝B _b

C _r＝C _g，C _g＝C _b

D _r＝D _g，D _g＝D _b

Wherein, A is described top left corner pixel, and B is described upper right corner pixel, and C is described lower left corner pixel, and D is described lower right corner pixel, A _r, A _g, A _bbe respectively the red value of pixel A, green numerical value and blue values, B _r, B _g, B _bbe respectively the red value of pixel B, green numerical value and blue values, C _r, C _g, C _bbe respectively the red value of pixel C, green numerical value and blue values, D _r, D _g, D _bbe respectively the red value of pixel D, green numerical value and blue values.

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 15 artificial type:

A _g＝0，A _b＝0

B _g＝0，B _b＝0

C _g＝0，C _b＝0

D _g＝0，D _b＝0

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 16 artificial type:

A _r＝0，A _b＝0

B _r＝0，B _b＝0

C _r＝0，C _b＝0

D _r＝0，D _b＝0

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 17 artificial type:

A _g＝0，A _r＝0

B _g＝0，B _r＝0

C _g＝0，C _r＝0

D _g＝0，D _r＝0

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the first artificial type:

ABS(A _y，B _y)＜THDY1，ABS(C _y，D _y)＜THDY1

ABS(A _u，B _u)＜THDU1，ABS(C _u，D _u)＜THDU1

ABS(A _v，B _v)＜THDV1，ABS(C _v，D _v)＜THDV1

ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)≤ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)≤ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u， _Bu)

ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)≤ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)

ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)≤ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

Wherein, ABS is the poor ABS function of two elements in bracket, THDY1 is lightness threshold value 1, THDU1 is the first colourity threshold value 1, and THDV1 is the second colourity threshold value 1 (value of each threshold value is rule of thumb chosen by those skilled in the art), and A is described top left corner pixel, B is described upper right corner pixel, C is described lower left corner pixel, and D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value obtain by the color gamut conversion formula of the RGB to YUV in above-mentioned steps S140:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, and the blue valve that b is this pixel, the lightness that Y is this pixel, U and V are respectively the first colourity and second colourity of this pixel.

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the second artificial type:

ABS(A _y，C _y)＜THDY1，ABS(B _y，D _y)＜THDY1

ABS(A _u，C _u)＜THDU1，ABS(B _u，D _u)＜THDU1

ABS(A _v，C _v)＜THDV1，ABS(B _v，D _v)＜THDV1

ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)≤ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)≤ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)

ABS(B _y，D _y)+ABS(B _v，D _v)+ABS(B _u，D _u)≤ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

ABS(B _y，D _y)+ABS(B _v，D _v)+ABS(B _u，D _u)≤ABS(D _y，C _y)+ABS(D _v，C _v)+ABS(D _u，C _u)

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 3rd artificial type:

ABS(C _y，B _y)＜THDY1，ABS(A _y，D _y)＜THDY1

ABS(C _u，B _u)＜THDU1，ABS(A _u，D _u)＜THDU1

ABS(C _v，B _v)＜THDV1，ABS(A _v，D _v)＜THDV1

ABS(C _y，B _y)+ABS(C _v，B _v)+ABS(C _u，B _u)≤ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

ABS(C _y，B _y)+ABS(C _v，B _v)+ABS(C _u，B _u)≤ABS(D _y，C _y)+ABS(D _v，C _v)+ABS(D _u，C _u)

ABS(A _y，D _y)+ABS(A _v，D _v)+ABS(A _u，D _u)≤ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

ABS(A _y，D _y)+ABS(A _v，D _v)+ABS(A _u，D _u)≤ABS(D _y，C _y)+ABS(D _v，C _v)+ABS(D _u，C _u)

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 4th artificial type:

ABS(D _y，B _y)＜THDY2，ABS(C _y，D _y)＜THDY2

ABS(D _u，B _u)＜THDU2，ABS(C _u，D _u)＜THDU2

ABS(D _v，B _v)＜THDV2，ABS(C _v，D _v)＜THDV2

ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)≤ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)≤ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

ABS(D _y，C _y)+ABS(D _v，C _v)+ABS(D _u，C _u)≤ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

ABS(D _y，C _y)+ABS(D _v，C _v)+ABS(D _u，C _u)≤ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

Wherein, ABS is the poor ABS function of two elements in bracket, THDY2 is lightness threshold value 2, and THDU2 is the first colourity threshold value 2, and THDV2 is the second colourity threshold value 2 (value of each threshold value is rule of thumb chosen by those skilled in the art).

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 5th artificial type:

ABS(D _y，B _y)＜THDY2，ABS(A _y，B _y)＜THDY2

ABS(D _u，B _u)＜THDU2，ABS(A _u，B _u)＜THDU2

ABS(D _v，B _v)＜THDV2，ABS(A _v，B _v)＜THDV2

ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)≤ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)≤ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)

ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)≤ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)≤ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)

In step 120, in the time meeting following formula, judge that this 2x2 coding unit makes type as Sixth Man:

ABS(A _y，B _y)＜THDY2，ABS(C _y，A _y)＜THDY2

ABS(A _u，B _u)＜THDU2，ABS(C _u，A _u)＜THDU2

ABS(A _v，B _v)＜THDV2，ABS(C _v，A _v)＜THDV2

ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)≤ABS(D _y，C _y)+ABS(D _v，C _v)+ABS(D _u，C _u)

ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)≤ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)

ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)≤ABS(D _y，C _y)+ABS(D _v，C _v)+ABS(D _u，C _u)

ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)≤ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 7th artificial type:

ABS(A _y，C _y)＜THDY2，ABS(C _y，D _y)＜THDY2

ABS(A _u，C _u)＜THDU2，ABS(C _u，D _u)＜THDU2

ABS(A _v，C _v)＜THDV2，ABS(C _v，D _v)＜THDV2

ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)≤ABS(B _y，D _y)+ABS(B _v，D _v)+ABS(B _u，D _u)

ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)≤ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

ABS(D _y，C _y)+ABS(D _v，C _v)+ABS(D _u，C _u)≤ABS(B _y，D _y)+ABS(B _v，D _v)+ABS(B _u，D _u)

ABS(D _y，C _y)+ABS(D _v，C _v)+ABS(D _u，C _u)≤ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 8th artificial type:

temp1＝ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

temp2＝ABS(A _y，C _y)+ABS(A _v，C _y)+ABS(A _u，C _u)

temp3＝ABS(A _y，D _y)+ABS(A _v，D _v)+ABS(A _u，D _u)

temp4＝ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)

temp5＝ABS(C _y，B _y)+ABS(C _v，B _v)+ABS(C _u，B _u)

temp6＝ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)

MIN(temp1，temp2，temp3，temp4，temp5，temp6)＝temp1

ABS(A _y，B _y)＜THDY4

ABS(A _v，B _v)＜THDV4

ABS(A _u，B _u)＜THDU4

Or ABS (C _y, D _y) > THDY3

Or ABS (C _v, D _v) > THDV3

Or ABS (C _u, D _u) > THDU3

Wherein, ABS is the poor ABS function of two elements in bracket, THDY3 is lightness threshold value 3, THDU3 is the first colourity threshold value 3, THDV3 is the second colourity threshold value 3, THDY4 is lightness threshold value 4, and THDU4 is the first colourity threshold value 4, and THDV4 is the second colourity threshold value 4 (value of each threshold value is rule of thumb chosen by those skilled in the art).

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 9th artificial type:

temp1＝ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

temp2＝ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

temp3＝ABS(A _y，D _y)+ABS(A _v，D _v)+ABS(A _u，D _u)

temp4＝ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)

temp5＝ABS(C _y，B _y)+ABS(C _v，B _v)+ABS(C _u，B _u)

temp6＝ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)

MIN(temp1，temp2，temp3，temp4，temp5，temp6)＝temp6

ABS(C _y，D _y)＜THDY4

ABS(C _v，D _v)＜THDV4

ABS(C _u，D _u)＜THDU4

Or ABS (A _y, B _y) > THDY3

Or ABS (A _v, B _v) > THDV3

Or ABS (A _u, B _u) > THDU3

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the tenth artificial type:

temp1＝ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

temp2＝ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

temp3＝ABS(A _y，D _y)+ABS(A _v，D _v)+ABS(A _u，D _u)

temp4＝ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)

temp5＝ABS(C _y，B _y)+ABS(C _v，B _v)+ABS(C _u，B _u)

temp6＝ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)

MIN(temp1，temp2，temp3，temp4，temp5，temp6)＝temp2

ABS(A _y，C _y)＜THDY4

ABS(A _v，C _v)＜THDV4

ABS(A _u，C _u)＜THDU4

Or ABS (B _y, D _y) > THDY3

Or ABS (B _v, D _v) > THDV3

Or ABS (B _u, D _u) > THDU3

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 11 artificial type:

temp1＝ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

temp2＝ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

temp3＝ABS(A _y，D _y)+ABS(A _v，D _v)+ABS(A _u，D _u)

temp4＝ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)

temp5＝ABS(C _y，B _y)+ABS(C _v，B _v)+ABS(C _u，B _u)

temp6＝ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)

MIN(temp1，temp2，temp3，temp4，temp5，temp6)＝temp4

ABS(B _y，B _y)＜THDY4

ABS(D _v，B _v)＜THDV4

ABS(D _u，B _u)＜THDU4

Or ABS (C _y, A _y) > THDY3

Or ABS (C _v, A _v) > THDV3

Or ABS (C _u, A _u) > THDU3

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 12 artificial type:

temp1＝ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

temp2＝ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

temp3＝ABS(A _y，D _y)+ABS(A _v，D _v)+ABS(A _u，D _u)

temp4＝ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)

temp5＝ABS(C _y，B _y)+ABS(C _v，B _v)+ABS(C _u，B _u)

temp6＝ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)

MIN(temp1，temp2，temp3，temp4，temp5，temp6)＝temp3

ABS(A _y，D _y)＜THDY4

ABS(A _v，D _v)＜THDV4

ABS(A _u，D _u)＜THDU4

Or ABS (C _y, B _y) > THDY3

Or ABS (C _v, B _v) > THDV3

Or ABS (C _u, B _u) > THDU3

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 13 artificial type:

temp1＝ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

temp2＝ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

temp3＝ABS(A _y，D _y)+ABS(A _v，D _v)+ABS(A _u，D _u)

temp4＝ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)

temp5＝ABS(C _y，B _y)+ABS(C _v，B _v)+ABS(C _u，B _u)

temp6＝ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)

MIN(temp1，temp2，temp3，temp4，temp5，temp6)＝temp5

ABS(C _y，B _y)＜THDY4

ABS(C _v，B _v)＜THDV4

ABS(C _u，B _u)＜THDU4

Or ABS (A _y, D _y) > THDY3

Or ABS (A _v, D _v) > THDV3

Or ABS (A _u, D _u) > THDU3

In step S160, go out outside above-mentioned natural type sorting technique, can also divide as follows natural type: 2x2 frequency domain unit is divided into the first natural type, the second nature type or Third Nature type, wherein:

When the H element of the first colourity 2x2 frequency domain unit meets following formula,

H＞THD1

Judge that described 2x2 coding unit is as the first natural type;

When F element and G element in the first colourity 2x2 frequency domain unit meet following formula,

MAX(ABS(F，0)，ABS(G，0))≤THD2

And F element and G element in the second colourity 2x2 frequency domain unit meet following formula,

MAX(ABS(F，0)，ABS(G，0))≤THD3

Judge that described 2x2 coding unit is as the second nature type;

Do not meet the first natural type and the second nature type condition, judge that described 2x2 coding unit is as Third Nature type;

Wherein, THD1 is the first threshold value, and THD2 is the second threshold value, and THD3 is the 3rd threshold value (value of each threshold value is rule of thumb chosen by those skilled in the art).

Fig. 9 is the differential errors coding that adopts the 2x2 coding unit of above-mentioned expansion rear 17 kinds of artificial types, quantize and the schematic diagram of the coding of tabling look-up.In Fig. 9, numeral figure place, for example 8,7 represent respectively 8 and 7, and oblique line represents table lookup operation, and backslash represents quantization operation.

In step S130, in the time that this 2x2 coding unit 220 is in the first artificial type, the second artificial type and the 3rd artificial type, use the wherein mean value of two pixels of 8 records, use one 6 of 6 or 7 records or 7 bit table cases to put, the content that records that these 6 or 7 bit table cases are put is: these 6 or all of 7 bit table lattice record in content, and the difference of the mean value of two pixels that record with mean value and 8 of the aforesaid uses of other two pixels in this 2x2 coding unit differs reckling.For example, 2x2 coding unit as shown in figure 10, only record: (128+128)/2=128 (using 8 records) and difference (127+127)/2-(128+128)/2=-1 (using one 7 chartings).

In step S130, in the time that this 2x2 coding unit 220 is in the artificial type of the 4th artificial type to the seven, use the wherein mean value of three pixels of 8 records, use 7 or 6 quantized values that record another one pixel in this 2x2 coding unit.For example, first the color numerical value (128) of the color numerical value (129) of the color numerical value (127) of pixel B, pixel C and pixel D is added and obtains 128 divided by 3 again with reference to Figure 11, round up again and obtain 128, use 8 and record numerical value 128.The color numerical value (28) of pixel A is carried out to quantization operations, then the fractional part acquisition numerical value 7 that rounds up, use 6 and record numerical value 7.In the time that the color of pixel A is green, uses 7 and record numerical value 14.This quantization operations is calculated by aforesaid quantitative formula, repeats no more herein.

In step S130, in the time that this 2x2 coding unit 220 is in the artificial type of the 8th artificial type to the 13, use the wherein quantized value of two pixel average of 5 records, use 4 quantized values that record respectively all the other two pixels; Or use the wherein quantized value of two pixel average of 7 records, use 5 quantized values that record all the other two pixels.Being about to two close pixel color numerical value averages, and carry out quantization operations, and using 7 (or 5) to carry out record, all the other two pixel color numerical value directly carry out respectively quantization operations and use respectively 5 (or 4) to carry out record.For example, first the color numerical value (23) of the color numerical value (21) of pixel B and pixel D is added and obtains 22 divided by 2 again with reference to Figure 12, carry out quantization operations to 22 and obtain round (22/2)=11, use 7 and record numerical value 11; The color numerical value (7) of pixel A is carried out to quantization operations, then the fractional part acquisition numerical value 1 that rounds up, use 5 and record numerical value 1; The color numerical value (40) of pixel C is carried out to quantization operations, then the fractional part acquisition numerical value 5 that rounds up, use 5 and record numerical value 5.

In step S130, in the time that this 2x2 coding unit 220 is in the artificial type of the 14 artificial type to the 17, from the above-mentioned formula about the 14 artificial type to the 17 artificial types, so-called single channel is that pixel only has red (R), green (G), blue (B) or gray scale (gray level) data, so these data only have RGB 24 triple channel data 1/3, therefore can use 8 to carry out complete record to these data.

For the dividing mode of above-mentioned 3 kinds of natural types, please refer to Figure 13, wherein back slash represents quantization operation, slash represents table lookup operation.

Wherein, quantization operation adopts formula:

$x_Q=\mathrm{Round}\left(\frac{x}{Q}\right)$

Wherein Q is known quantizing factor, and Round is the function that rounds up, the value x after record quantizes _q.

For example,, with 7 records 0～255, Q=256/ (2 ⁷)=2.

About table lookup operation, for example, with reference to Figure 14, in 4 bit table lattice, have 2 ⁴=16 record values, if this element value approaches j value in form most, record " j ", " j " value can be calculated according to following formula:

[a ₁，a ₂，a ₃，...，a _k-2，a _k-1，a _k]，

sign[F-a _j]·sign[a _j+1-F]≥0， (2)

Wherein a ₁～a _kfor 16 values that record altogether in this form of 4, it is sequentially arranged from small to large.Sign is the function of the sign of this value of output, and F is the value of wanting to table look-up, and once meet formula (2), stores j value.

In step S170, this 2x2 frequency domain unit is quantized and the coding of tabling look-up, to produce the second coded data.

In step S170, in the time that this 2x2 frequency domain unit is the first natural type, use the quantized value of 5 E elements that record this lightness 2x2 frequency domain unit, F element, G element; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the difference reckling of the value of the H element of this lightness 2x2 frequency domain unit.

The value of the element of this lightness 2x2 frequency domain unit is-128～127, thus need first carry out shift operation, so that the value of the element of this lightness 2x2 frequency domain unit is displaced to 0～255 by-128～127.In step S170, be that the numerical value of E element, F element, G element is carried out to quantization operations, round up for fractional part, re-use 5 records.Because the numerical value of the E element of this lightness 2x2 frequency domain unit, F element, G element is 8, in the time using 5 to record, therefore quantizing factor Q is 8.The H element of this lightness 2x2 frequency domain unit uses one 3 bit table lattice to carry out table lookup operation, and it is identical that the principle of this table lookup operation and aforementioned 5 bit table lattice are tabled look-up, and repeats no more.

In step S170, in the time that this 2x2 frequency domain unit is the first natural type, use 5 quantized values that record the E element of this first colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the difference reckling of the value of the F element of this first colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the difference reckling of the value of the G element of this first colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the difference reckling of the value of the H element of this first colourity 2x2 frequency domain unit 770.

In step S170, in the time that this 2x2 frequency domain unit is the first natural type, use 5 quantized values that record the E element of this second colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the difference reckling of the value of the F element of this second colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the difference reckling of the value of the G element of this second colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the difference reckling of the value of the H element of this second colourity 2x2 frequency domain unit.

In step S170, in the time that this 2x2 frequency domain unit is the second nature type, use the quantized value of 7 E elements that record this lightness 2x2 frequency domain unit, F element, G element; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the difference reckling of the value of the H element of this lightness 2x2 frequency domain unit.

The value of the element of this lightness 2x2 frequency domain unit is-128～127, thus need first carry out shift operation, so that the value of the element of this lightness 2x2 frequency domain unit is displaced to 0～255 by-128～127.In step S170, be that the numerical value of E element, F element, G element is carried out to quantization operations, round up for fractional part, re-use 7 records.Because the numerical value of the E element of this lightness 2x2 frequency domain unit, F element, G element is 8, in the time using 7 to record, therefore quantizing factor Q is 2.The H element of this lightness 2x2 frequency domain unit uses one 4 bit table lattice to carry out table lookup operation, and it is identical that the principle of this table lookup operation and aforementioned 7 bit table lattice are tabled look-up, and repeats no more.

In step S170, in the time that this 2x2 frequency domain unit is the second nature type, use 6 quantized values that record the E element of this first colourity 2x2 frequency domain unit; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the F element of this first colourity 2x2 frequency domain unit and the mean value of G element; Do not record the H element of this first colourity 2x2 frequency domain unit.

The value of the element of this first colourity 2x2 frequency domain unit is-255～255, thus need first carry out a shift operation, so that the value of the element of this first colourity 2x2 frequency domain unit is displaced to 0～510 by-255～255.Therefore the element of this first colourity 2x2 frequency domain unit 770 is 9, in the time that the E element of this first colourity 2x2 frequency domain unit 770 is recorded in 6 of uses, need first carry out quantization operations, and wherein, quantizing factor Q is 8.

It is that F element and the G element of this first colourity 2x2 frequency domain unit are first averaged, then one 2 bit table lattice is tabled look-up with this mean value, and it is identical that the principle of this table lookup operation and aforementioned 7 bit table lattice are tabled look-up, and repeats no more.

In step S170, in the time that this 2x2 frequency domain unit is the second nature type, use 7 quantized values that record the E element of this second colourity 2x2 frequency domain unit; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the mean value of F element in this second colourity 2x2 frequency domain unit and G element; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the H element of this second colourity 2x2 frequency domain unit.

The value of the element of this second colourity 2x2 frequency domain unit is-255～255, thus need first carry out a shift operation, so that the value of the element of this second colourity 2x2 frequency domain unit is displaced to 0～510 by-255～255.Therefore the element of this second colourity 2x2 frequency domain unit 780 is 9, in the time that the E element of this second colourity 2x2 frequency domain unit is recorded in 7 of uses, need first carry out quantization operations, and wherein, quantizing factor Q is 4.

It is that F element and the G element of this second colourity 2x2 frequency domain unit are first averaged, then one 2 bit table lattice is tabled look-up with this mean value.It is identical that the principle that these 2 bit table lattice are tabled look-up and aforementioned 7 bit table lattice are tabled look-up, and repeats no more.

In step S170, in the time that this 2x2 frequency domain unit is Third Nature type, use 5 quantized values that record the E element of this lightness 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the F element of this lightness 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the G element of this lightness 2x2 frequency domain unit; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the value of the H element of this lightness 2x2 frequency domain unit.

In step S170, in the time that this 2x2 frequency domain unit is Third Nature type, use 4 quantized values that record the E element of this first colourity 2x2 frequency domain unit; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the value of the F element of this first colourity 2x2 frequency domain unit; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the value of the G element of this first colourity 2x2 frequency domain unit; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the value of the H element of this first colourity 2x2 frequency domain unit.

In step S170, in the time that this 2x2 frequency domain unit is Third Nature type, use 4 quantized values that record the E element of this second colourity 2x2 frequency domain unit; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the value of the F element of this second colourity 2x2 frequency domain unit; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the value of the G element of this second colourity 2x2 frequency domain unit; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the value of the H element of this second colourity 2x2 frequency domain unit.

In hardware structure, can use OTP (One Time Programable, One Time Programmable chip), ROM (Read-Only Memory, read-only memory) or NVM (Nonvolatile memory, nonvolatile memory) record form content.

In step S180, receive this first coding data or this second coded data, and this first coding data or this second coded data are encapsulated to (packaging), and then generate the coding package with fixed bit size.

As shown in Fig. 9 and Figure 13, step S180 uses 1 (main packet header) whether to record this 2x2 coding unit 220 as artificial type or natural type, re-uses 4 (the first sub-packet header) to record whether in the artificial type of the first artificial type to the 17 of this 2x2 coding unit 220.Therefore, when this 2x2 coding unit 220 is the first artificial type, the second artificial type, when in the 3rd artificial type one, position after its coding and encapsulation is counted as 48 (=1+4+8+7+8+6+8+6), in the time that this 2x2 coding unit 220 is in the 4th to the 7th artificial type, position counting after its coding and encapsulation is still 48 (=1+4+8+7+8+6+8+6), in the time that this 2x2 coding unit 220 is in the 8th to the 13 artificial type, position after its coding and encapsulation is counted as 48 (=1+4+5+4+4+7+5+5+5+4+4), in the time that this 2x2 coding unit 220 is in the 14 to the 17 artificial type, position after its coding and encapsulation is counted as 39 (=1+4+2+8+8+8+8).In the time that this 2x2 coding unit 220 is natural type, re-use 1 (the second sub-packet header) whether to record this 2x2 coding unit 220 as the first natural type or second, Third Nature type, in the time that this 2x2 coding unit 220 is the first natural type, position counting after its coding and encapsulation is still 48 (=1+1+5+5+5+3+5+3+3+3+5+3+3+3), in the time that this 2x2 coding unit 220 is the second nature type or Third Nature type, re-use 1 (inferior packet header) whether to record this 2x2 coding unit 220 as the second nature type or Third Nature type, in the time that this 2x2 coding unit 220 is the second nature type, position counting after its coding and encapsulation is still 48 (=1+1+1+7+7+7+4+6+2+7+2+3), in the time that this 2x2 coding unit 220 is Third Nature type, position counting after its coding and encapsulation is still 48 (=1+1+1+5+3+3+2+4+4+4+4+4+4+4+4).

Embodiment bis-: in 2x2 coding unit, red (r) of each pixel, blue (g), green (b) three kinds of colors all adopt 6 to carry out record, therefore this 2x2 coding unit 220 is 72 (=6 × 3 × 4) position.

In embodiment bis-, artificial type is with reference to 17 kinds of figure 8.Wherein, the first artificial type of artificial type to the seven and the artificial type of the 14 artificial type to the 17 are identical with the rule in previous embodiment one, and the artificial type adjustment of the 8th artificial type to the 13 is as follows.

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 8th artificial type:

temp1＝ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

temp2＝ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

temp3＝ABS(A _y，D _y)+ABS(A _v，D _v)+ABS(A _u，D _u)

temp4＝ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)

temp5＝ABS(C _y，B _y)+ABS(C _v，B _v)+ABS(C _u，B _u)

temp6＝ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)

MIN(temp1，temp2，temp3，temp4，temp5，temp6)＝temp1

ABS(A _y，B _y)＜THDY4

ABS(A _v，B _v)＜THDV4

ABS(A _u，B _u)＜THDU4

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 9th artificial type:

temp1＝ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

temp2＝ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

temp3＝ABS(A _y，D _y)+ABS(A _v，D _v)+ABS(A _u，D _u)

temp4＝ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)

temp5＝ABS(C _y，B _y)+ABS(C _v，B _v)+ABS(C _u，B _u)

temp6＝ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)

MIN(temp1，temp2，temp3，temp4，temp5，temp6)＝temp6

ABS(C _y，D _y)＜THDY4

ABS(C _v，D _v)＜THDV4

ABS(C _u，D _u)＜THDU4

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the tenth artificial type:

temp1＝ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

temp2＝ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

temp3＝ABS(A _y，D _y)+ABS(A _v，D _v)+ABS(A _u，D _u)

temp4＝ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)

temp5＝ABS(C _y，B _y)+ABS(C _v，B _v)+ABS(C _u，B _u)

temp6＝ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)

MIN(temp1，temp2，temp3，temp4，temp5，temp6)＝temp2

ABS(A _y，C _y)＜THDY4

ABS(A _v，C _v)＜THDV4

ABS(A _u，C _u)＜THDU4

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 11 artificial type:

temp1＝ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

temp2＝ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

temp3＝ABS(A _y，D _y)+ABS(A _v，D _v)+ABS(A _u，D _u)

temp4＝ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)

temp5＝ABS(C _y，B _y)+ABS(C _v，B _v)+ABS(C _u，B _u)

temp6＝ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)

MIN(temp1，temp2，temp3，temp4，temp5，temp6)＝temp4

ABS(D _y，B _y)＜THDY4

ABS(D _v，B _v)＜THDV4

ABS(D _u，B _u)＜THDU4

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 12 artificial type:

temp1＝ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

temp2＝ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

temp3＝ABS(A _y，D _y)+ABS(A _v，D _v)+ABS(A _u，D _u)

temp4＝ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)

temp5＝ABS(C _y，B _y)+ABS(C _v，B _v)+ABS(C _u，B _u)

temp6＝ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)

MIN(temp1，temp2，temp3，temp4，temp5，temp6)＝temp3

ABS(A _y，D _y)＜THDY4

ABS(A _v，D _v)＜THDV4

ABS(A _u，D _u)＜THDU4

In step 120, in the time meeting following formula, judge that this 2x2 coding unit is as the 13 artificial type:

temp1＝ABS(A _y，B _y)+ABS(A _v，B _v)+ABS(A _u，B _u)

temp2＝ABS(A _y，C _y)+ABS(A _v，C _v)+ABS(A _u，C _u)

temp3＝ABS(A _y，D _y)+ABS(A _v，D _v)+ABS(A _u，D _u)

temp4＝ABS(D _y，B _y)+ABS(D _v，B _v)+ABS(D _u，B _u)

temp5＝ABS(C _y，B _y)+ABS(C _v，B _v)+ABS(C _u，B _u)

temp6＝ABS(C _y，D _y)+ABS(C _v，D _v)+ABS(C _u，D _u)

MIN(temp1，temp2，temp3，temp4，temp5，temp6)＝temp5

ABS(C _y，B _y)＜THDY4

ABS(C _v，B _v)＜THDV4

ABS(C _u，B _u)＜THDU4

For the natural type of embodiment 2, can also divide as follows: 2x 2 frequency domain unit are divided into the first natural type or the second nature type.

When F element and G element in the first colourity 2x2 frequency domain unit meet following formula,

MAX(ABS(F，0)，ABS(G，0))≤THD1

And F element and G element in the second colourity 2x2 frequency domain unit meet following formula,

MAX(ABS(F，0)，ABS(G，0))≤THD2

Judge that described 2x2 coding unit is as the first natural type, otherwise judge that described 2x2 coding unit is as the second nature type.Wherein, as previously mentioned, EFGH is the value of YUV after discrete cosine transform, and THD1 and THD2 are threshold value.

Figure 15 be the embodiment 2 2x2 coding unit that adopts the rear 17 kinds of artificial types of above-mentioned expansion differential errors coding, quantize and the schematic diagram of the coding of tabling look-up.

In step S130, when this 2x2 coding unit 220 is the first artificial type, when in the second artificial type and the 3rd artificial type one, the pixel that blank square represents and have double-head arrow symbol to represent that two pixels average, only record mean value one time, the pixel that slash represents is (less than the pixel of 6, as 4, 5), the only difference of record and rest of pixels, use the look-up method in aforementioned, use 5 record one 5 bit table cases to put, the content that records that this 5 bit table case is put is: all of these 5 bit table lattice record in content, the difference of the mean value of two pixels that record with mean value and 6 of the aforesaid uses of other two pixels in this 2x2 coding unit differs reckling.For example, 2x2 coding unit as shown in figure 16, only record: (63+63)/2=63 (using 6 records) and difference (62+62)/2-(63+63)/2=-1 (using one 5 chartings).

In step S130, in the time that this 2x2 coding unit 220 is in the artificial type of the 4th artificial type to the seven, three akin pixel color numerical value are averaged, and use 6 to carry out record, the color numerical value of dissimilar pixel is carried out to quantization operations (in figure, back slash represents quantization operations).For example, first the color numerical value (24) of the color numerical value (25) of the color numerical value (23) of pixel B, pixel C and pixel D is added and obtains 24 divided by 3 again with reference to Figure 17, then the acquisition 24 that rounds up, use 6 and record numerical value 24.The color numerical value (7) of pixel A is carried out to quantization operations, then the fractional part acquisition numerical value 2 that rounds up, use 4 and record numerical value 2.In the time that the color of pixel A is green, uses 5 and record numerical value 4.This quantization operations is calculated by aforesaid quantitative formula, repeats no more herein.

In step S130, in the time that this 2x2 coding unit 220 is in the artificial type of the 8th artificial type to the 13, two close pixel color numerical value are averaged, and carry out quantization operations, and using 5 (or 4) to carry out record, all the other two pixel color numerical value directly carry out respectively quantization operations and use respectively 3 to carry out record.For example, first the color numerical value (23) of the color numerical value (21) of pixel B and pixel D is added and obtains 22 divided by 2 again with reference to Figure 18, carry out quantization operations to 22 and obtain round (22/2)=11, use 5 (or 4) to record numerical value 11; The color numerical value (7) of pixel A is carried out to quantization operations, then the fractional part acquisition numerical value 1 that rounds up, use 3 and record numerical value 1; The color numerical value (40) of pixel C is carried out to quantization operations, then the fractional part acquisition numerical value 5 that rounds up, use 3 and record numerical value 5.

In step S130, in the time that this 2x2 coding unit 220 is in the artificial type of the 14 artificial type to the 17, from the above-mentioned formula about the 14 artificial type to the 17 artificial types, so-called single channel is that pixel only has red (R), green (G), blue (B) or gray scale (grayl evel) data, so these data only have RGB 24 triple channel data 1/3, therefore can use 6 to carry out complete record to these data.

For the dividing mode of above-mentioned 2 kinds of natural types, please refer to Figure 19, wherein back slash represents quantization operation, slash represents table lookup operation.

Wherein, quantization operation adopts formula:

$x_Q=\mathrm{Round}\left(\frac{x}{Q}\right)$

Wherein Q is known quantizing factor, and Round is the function that rounds up, the value x after record quantizes _q.

For example,, with 5 records 0～63, Q=64/ (2 ⁵)=2.

About table lookup operation, for example, with reference to Figure 20, in 3 bit table lattice, have 2 ³=8 record values, if this element value approaches j value in form most, record " j ", " j " value can be calculated according to following formula:

[a ₁，a ₂，a ₃，...，a _k-2，a _k-1，a _k]，

sign[F-a _j]·sign[a _j+1-F]≥0， (2)

Wherein a ₁～a _kfor 8 values that record altogether in this form of 3, it is sequentially arranged from small to large.Sign is the function of the sign of this value of output, and F is the value of wanting to table look-up, and once meet formula (2), stores j value.

When in step S120, while judging this 2x2 coding unit 220 not as in the artificial type of the first artificial type to the 17 one, represent that this 2x2 coding unit 220 is natural type, therefore in step S140,2x2 coding unit 220 to this natural type carries out color gamut conversion, to obtain a 2x2 gamut conversion unit.

In step S140, the scope of the value of the element in this lightness 2x2 gamut conversion unit 710 is 0～63, the scope of the value of the element of this first colourity 2x2 gamut conversion unit 720 and the second colourity 2x2 gamut conversion unit 730 is-63～63, therefore the element of this lightness 2x2 gamut conversion unit 710 is 6, the element of this first colourity 2x2 gamut conversion unit 720 and the second colourity 2x2 gamut conversion unit 730 is 7, and this is only computational process, do not affect the position counting of last coding.Carrying out before next step S150, need first the value of the element of this lightness 2x2 gamut conversion unit 710 to be displaced to-32～31 by 0～63.

In step S150, the scope of the value of the each element in this lightness 2x2 frequency domain unit 760 is-32～31, the scope of the value of each element of this first colourity 2x2 frequency domain unit 770 and the second colourity 2x2 frequency domain unit 780 is-63～63, therefore each element of this lightness 2x2 frequency domain unit 760 is 6, each element of this first colourity 2x2 frequency domain unit 770 and the second colourity 2x2 frequency domain unit 780 is 7, and this is only computational process, do not affect the position counting of last coding.

In step S170, in the time that this 2x2 frequency domain unit 750 is the first natural type 380, use 5 E element, F element, G elements that record this lightness 2x2 frequency domain unit 760; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the difference reckling of the value of the H element of this lightness 2x2 frequency domain unit 760.

The value of the element of this lightness 2x2 frequency domain unit 760 is-32～31, thus need first carry out shift operation, so that the value of the element of this lightness 2x2 frequency domain unit 760 is displaced to 0～63 by-32～31.In step S170, be that the numerical value of E element, F element, G element is carried out to quantization operations, round up for fractional part, re-use 5 records.Because the numerical value of the E element of this lightness 2x2 frequency domain unit 760, F element, G element is 6, in the time using 5 to record, therefore quantizing factor Q is 2.The H element of this lightness 2x2 frequency domain unit 760 uses one 3 bit table lattice to carry out table lookup operation, and it is identical that the principle of this table lookup operation and aforementioned 5 bit table lattice are tabled look-up, and repeats no more.

In step S170, in the time that this 2x2 frequency domain unit 750 is the first natural type 380, use 5 E elements that record this first colourity 2x2 frequency domain unit 770; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the F element of this first colourity 2x2 frequency domain unit 770 and the mean value of G element; Do not record the H element of this first colourity 2x2 frequency domain unit 770.

The value of the element of this first colourity 2x2 frequency domain unit 770 is-63～63, thus need first carry out a shift operation, so that the value of the element of this first colourity 2x2 frequency domain unit 770 is displaced to 0～126 by-63～63.Therefore the element of this first colourity 2x2 frequency domain unit 770 is 7, in the time that the E element of this first colourity 2x2 frequency domain unit 770 is recorded in 5 of uses, need first carry out quantization operations, and wherein, quantizing factor Q is 4.

It is that F element and the G element of this first colourity 2x2 frequency domain unit 770 are first averaged, then one 2 bit table lattice is tabled look-up with this mean value, and it is identical that the principle of this table lookup operation and aforementioned 5 bit table lattice are tabled look-up, and repeats no more.

In step S170, in the time that this 2x2 frequency domain unit 750 is the first natural type 380, use 5 quantized values that record the E element of this second colourity 2x2 frequency domain unit 780; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the mean value of F element in this second colourity 2x2 frequency domain unit 780 and G element; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the value of the H element of this second colourity 2x2 frequency domain unit 780.

The value of the element of this second colourity 2x2 frequency domain unit 780 is-63～63, thus need first carry out a shift operation, so that the value of the element of this second colourity 2x2 frequency domain unit 780 is displaced to 0～126 by-63～63.Therefore the element of this second colourity 2x2 frequency domain unit 780 is 7, in the time that the E element of this second colourity 2x2 frequency domain unit 780 is recorded in 5 of uses, need first carry out quantization operations, and wherein, quantizing factor Q is 4.

It is that F element and the G element of this second colourity 2x2 frequency domain unit 780 are first averaged, then one 2 bit table lattice is tabled look-up with this mean value.It is identical that the principle that these 2 bit table lattice are tabled look-up and aforementioned 5 bit table lattice are tabled look-up, and repeats no more.

In step S170, in the time that this 2x2 frequency domain unit 750 is the second nature type 390, use 4 quantized values that record the E element of lightness 2x2 frequency domain unit 760; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the F element of this lightness 2x2 frequency domain unit 760; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the G element of this lightness 2x2 frequency domain unit 760; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the value of the H element of this lightness 2x2 frequency domain unit 760.This technical staff can learn according to the technology of the present invention in order to be familiar with for these quantizing factors Q and table lookup operation, repeats no more.

In step S170, in the time that this 2x2 frequency domain unit 750 is the second nature type 390, use 3 quantized values that record the E element of this first colourity 2x2 frequency domain unit 770; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the F element of this first colourity 2x2 frequency domain unit 770; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the G element of this first colourity 2x2 frequency domain unit 770; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the value of the H element of this first colourity 2x2 frequency domain unit 760.

In step S170, in the time that this 2x2 frequency domain unit 750 is the second nature type 390, use 3 quantized values that record the E element of this second colourity 2x2 frequency domain unit 780; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the F element of this second colourity 2x2 frequency domain unit 780; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the G element of this second colourity 2x2 frequency domain unit 780; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the value of the H element of this second colourity 2x2 frequency domain unit 780.

In hardware structure, can use OTP (One Time Programable, One Time Programmable chip), ROM (Read-Only Memory, read-only memory) or NVM (Nonvolatile memory, nonvolatile memory) record form content.

As shown in Figure 15 and Figure 19, step S180 uses 1 (main packet header) whether to record this 2x2 coding unit 220 as artificial type or natural type, re-uses 4 (the first sub-packet header) to record whether in the artificial type of the first artificial type to the 17 of this 2x2 coding unit 220.Therefore, when this 2x2 coding unit 220 is the first artificial type, the second artificial type, when in the 3rd artificial type one, position after its coding and encapsulation is counted as 36 (=1+4+6+4+6+5+6+4), in the time that this 2x2 coding unit 220 is in the 4th to the 7th artificial type, position counting after its coding and encapsulation is still 36 (=1+4+6+4+6+5+6+4), in the time that this 2x2 coding unit 220 is in the 8th to the 13 artificial type, position after its coding and encapsulation is counted as 36 (=1+4+4+3+3+5+3+3+4+3+3), in the time that this 2x2 coding unit 220 is in the 14 to the 17 artificial type, position after its coding and encapsulation is counted as 31 (=1+4+2+6+6+6+6).In the time that this 2x2 coding unit 220 is natural type, re-use 1 (the second sub-packet header) whether to record this 2x2 coding unit 220 as the first natural type or the second nature type, in the time that this 2x2 coding unit 220 is the first natural type, position counting after its coding and encapsulation is still 36 (=1+1+5+5+5+3+5+2+2+5+2), in the time that this 2x2 coding unit 220 is the second nature type, the position counting after its coding and encapsulation is still 36 (=1+1+4+3+3+2+3+3+3+2+3+3+3+2).

Figure 21 is the flow chart of a kind of fixing compression ratio image decompression method based on 2x2 coding unit of the present invention, it is that the coding package of a fixed bit size is decoded, to produce a 2x2 decoding unit in an image, this 2x2 decoding unit comprises and is four pixels that matrix is arranged, and this image has at least one 2x2 decoding unit.

First,, in step S805, receive a coding package.

In step S810, judge according to the main packet header of this coding package (1 bit) whether this coding package is artificial type, if so, judge that this coding package is behaved to make the coding package of type, otherwise, judge the coding package that this coding package is natural type.

In step S815, to being judged to be the coding package of artificial type, judge according to first of this coding package the sub-packet header (2 bit) whether it is in the artificial type of the first artificial type to the three again, wherein, the first artificial type is four pixels, two horizontal stripes in horizontal direction, the second artificial type is two vertical stripes that four pixels are vertical direction, and the 3rd artificial type is the two slanted bar lines intersections that four pixels are miter angle direction.

In step S820, to being judged to be artificial type and being not the coding package of the first artificial type to the three artificial types, then judge according to the sub-packet header of this coding package (2 bit) and second son packet header (2bit) whether it is in the artificial type of the 4th artificial type to the seven.Wherein, the artificial type of the 4th artificial type to the seven is the combination with single-point triangular in shape of four pixels; The 4th artificial type is that lower left corner pixel, upper right corner pixel and lower right corner pixel are approximate; The 5th artificial type is that top left corner pixel, upper right corner pixel and lower right corner pixel are approximate; It is that top left corner pixel, lower left corner pixel and upper right corner pixel are approximate that Sixth Man is made type; The 7th artificial type is that top left corner pixel, lower left corner pixel and lower right corner pixel are approximate.

In step S825, the coding package of this artificial type is carried out to inverse quantization, counter table look-up decoding and contrast point error decoding, to produce one first decoded data.

In step S830, to the coding package of natural type, then according to second of this coding package the sub-packet header (1 bit), judge that it is the first natural type or the second nature type.

In step S835, the coding package of this natural type is carried out to inverse quantization and the anti-decoding of tabling look-up, to produce one second decoded data;

In step S840, this second decoded data is carried out to discrete cosine transform, to produce one the 3rd decoded data.In step S840, the transition matrix coefficient of this discrete cosine transform is:

$\left[\begin{array}{c}\stackrel{\&OverBar;}{A}\\ \stackrel{\&OverBar;}{B}\\ \stackrel{\&OverBar;}{C}\\ \stackrel{\&OverBar;}{D}\end{array}\right]\left[\begin{array}{cccc}1& 1& 1& 1\\ 1& -1& 1& -1\\ 1& 1& -1& -1\\ 1& -1& -1& 1\end{array}\right]\left[\begin{array}{c}E\\ F\\ G\\ H\end{array}\right].$

Wherein, E, F, G, H are this second decoded data, for the 3rd decoded data.

In step S845, the 3rd decoded data is carried out to color gamut conversion, to obtain one the 4th decoded data.In step S845, carry out YUV to RGB color gamut conversion, the transition matrix coefficient of this YUV to RGB color gamut conversion is:

$\left[\begin{array}{c}r\\ g\\ b\end{array}\right]=\left[\begin{array}{ccc}1.0& -0.5& -0.5\\ 1.0& 0.5& 0\\ 1.0& -0.5& 0.5\end{array}\right]\left[\begin{array}{c}Y\\ U\\ V\end{array}\right],$

Wherein, Y is the lightness of the pixel in the 3rd decoded data, the colourity that U and V are this pixel, and r is the red value of the pixel in the 4th decoded data, the green value that g is this pixel, the blue valve that b is this pixel.

In step S850, receive this first decoded data or the 4th decoded data, and this first decoded data or the 4th decoded data are rebuild, to produce a 2x2 decoding unit.

Figure 22 is the structure chart of the display system of the fixing compression ratio of a kind of application of the present invention based on 2x2 coding unit, it is for show image being compressed and decompressing, and this display system 900 comprises fixing compression ratio image compression device based on 2x2 coding unit of a display module 910, an image input equipment 920, one 930, fixing compression ratio image decompressing device 950, time schedule controller 960, multiple source electrode driver 970 and the multiple gate drivers 980 of an apparatus for temporary storage 940, based on 2x2 coding unit.

Display module 910 is for show image.Image input equipment 920 is for inputting show image.Fixing compression ratio image compression device 930 based on 2x2 coding unit is connected to image input equipment 920, for a 2x2 coding unit of show image is encoded, to produce the coding package corresponding with this 2x2 coding unit, wherein, this image has at least one 2x2 coding unit.

Apparatus for temporary storage 940 is connected to the fixing compression ratio image compression device 930 based on 2x2 coding unit, the coding package of exporting with the fixing compression ratio image compression device 930 of keeping in based on 2x2 coding unit.

Fixing compression ratio image decompressing device 950 based on 2x2 coding unit is connected to apparatus for temporary storage 940, with received code package, and this coding package is decompressed, to produce the 2x2 decoding unit corresponding with 2x2 coding unit.

Time schedule controller 960 is connected to the fixing compression ratio image decompressing device 950 based on 2x2 coding unit, for receiving 2x2 decoding unit, drives signal and shows data to produce the sequential of display module 910.

Multiple source electrode drivers 970 and multiple gate drivers 980 are connected to time schedule controller 960, sequential driving signal and the demonstration data exported for receiving this time schedule controller 960, and then drive display module 910.

Fixing compression ratio image compression device 930 is first to judge that 2x2 coding unit is artificial type or natural type, with the coding that carries out differential errors coding, quantizes and table look-up of the 2x2 coding unit to artificial type, and then generation first coding data, and to the 2x2 coding unit of the natural type coding that carries out color gamut conversion, discrete cosine transform, quantizes and table look-up, and then generation the second coded data, again this first coding data or this second coded data are encapsulated, to produce the coding package of fixing compression ratio.Wherein, this 2x2 coding unit is 96 (24bit version) position or 72 (18bit version) position, and this coding package corresponding with this 2x2 coding unit is 48 (24bit version) position or 36 (18bit version).

From above stated specification, the present invention is using the Pixel Dimensions of 2x2 as coding unit, by suitable classification and the suitable distribution of bit quantity, taking human eye vision response as prerequisite, suitably gives up more insensitive composition, reaches image compression and maintains the quality of image.

When above-mentioned coding unit classification, the classification of artificial type contributes to process as certain patterns such as font edge, gray scale variation, sawtooth, gridiron patterns, coordinates package recording method of the present invention, can make the coding unit of specific artificial type reach Lossless Compression.

In natural type, the YUV after step S140 color gamut conversion, lower for the response sensitivity of human eye with UV composition, therefore in the time that package records, give up or record corresponding frequency domain element with less position counting.Meanwhile, the element after discrete cosine transform is frequency domain, and high frequency element is lower for the response sensitivity of human eye, records high frequency element, to retain the more sensitive information of response for human eye with less position counting.

Simultaneously, color gamut conversion in step S140, step S150, step S840, step S850 or discrete cosine transform, the coefficient of its transition matrix for ± 1,0.25, ± 0.5 in the time that hardware is realized, can use simply shift unit (shifter) to replace multiplier, to save hardware cost.

In addition, the technology of the present invention is in the time applying for mobile phone, and the test pattern such as general artificial GTG and gridiron pattern of mobile phone can reach Lossless Compression and conciliate compression effectiveness, can save the memory demand that stores image on mobile phone simultaneously.And each 2x2 coding unit is equal independent operation in the time of compression or decompression, without with reference to other 2x2 coding units, and the compression ratio of each coding unit is all fixed as 0.5 (=36/72) or 0.5 (=48/96), without data such as any previous package of reference, pixel, picture frames (frame), can Real Time Compression and decompression, be that single coding unit enters, can complete single coding package.In like manner, single coding package enters, and can decompress and be reduced into single decoding unit, is particularly suitable for the special applications of arbitrary access (random access), as mobile phone shows with internal memory part frame updating (partially update).

From the above, no matter the present invention is with regard to object, means and effect, all different from prior art feature institute, has practical value.It should be noted that the various embodiments described above are only to give an example for convenience of explanation, the present invention's interest field required for protection should be as the criterion with claims scope, but not only limits to above-described embodiment.

The foregoing is only preferred embodiment of the present invention, in order to limit the present invention, within the spirit and principles in the present invention not all, any amendment of making, be equal to replacement, improvement etc., within all should being included in the scope of protection of the invention.

Claims (76)

1. the image compressing method with fixing compression ratio based on 2x2 coding unit, is characterized in that: the 2x2 coding unit in image is encoded, and described image is made up of at least one 2x2 coding unit, and described image compressing method comprises the following steps:

(A) receive 2x2 coding unit, described 2x2 coding unit comprises the top left corner pixel, upper right corner pixel, lower left corner pixel and the lower right corner pixel that are matrix arrangement, and the each pixel in described 2x2 coding unit has red value, green numerical value and blue values;

(B) judge whether described 2x2 coding unit is artificial type, if, judge that this 2x2 coding unit is as this artificial type, otherwise, judge that this 2x2 coding unit is natural type, wherein, described artificial type comprises: the first artificial type, represents these four pixels two horizontal stripes in horizontal direction; The second artificial type, represents that these four pixels are two vertical stripes of vertical direction; The 3rd artificial type, represents that these four pixels are two slanted bar lines intersections of miter angle direction; The artificial type of the 4th artificial type to the seven, represents the combination with single-point triangular in shape of these four pixels;

(C) to being judged to be the 2x2 coding unit of the artificial type coding that carries out differential errors coding, quantizes and table look-up, to produce first coding data;

(D) the 2x2 coding unit that is judged to be natural type is carried out to RGB to YUV color gamut conversion, to obtain 2x2 gamut conversion unit;

(E) described 2x2 gamut conversion unit is carried out to discrete cosine transform, to produce 2x2 frequency domain unit; And

(F) described 2x2 frequency domain unit is quantized and the coding of tabling look-up, to produce the second coded data;

Described the first artificial type, represents that described top left corner pixel and upper right corner pixel are approximate, and described lower left corner pixel and lower right corner pixel approximate; Described the second artificial type represents that described top left corner pixel and lower left corner pixel are approximate, and described upper right corner pixel and lower right corner pixel approximate; Described the 3rd artificial type, represents that described top left corner pixel and lower right corner pixel are approximate, and described lower left corner pixel and upper right corner pixel approximate; Described the 4th artificial type, represents that described lower left corner pixel, upper right corner pixel and lower right corner pixel are approximate; Described the 5th artificial type, represents that described top left corner pixel, upper right corner pixel and lower right corner pixel are approximate; Described Sixth Man is made type, represents that described top left corner pixel, lower left corner pixel and upper right corner pixel are approximate; Described the 7th artificial type, represents that described top left corner pixel, lower left corner pixel and lower right corner pixel are approximate;

(G) receive described first coding data or the second coded data, and this first coding data or this second coded data are encapsulated, to produce the coding package with fixing compression ratio.

2. image compressing method as claimed in claim 1, it is characterized in that, described artificial type also comprises the 8th artificial type in artificial type～17, wherein: eight, the 9th artificial type, represents these four pixels horizontal stripe in horizontal direction and the combination of two single-points; Ten, the 11 artificial type, represents that these four pixels are the combination of a vertical stripe and two single-points of vertical direction; The the 12, the 13 artificial type, represents that these four pixels are a slanted bar line of miter angle direction and the combination of two single-points;

Described the 8th artificial type, represents that described top left corner pixel and upper right corner pixel are approximate; Described the 9th artificial type, represents that described lower left corner pixel and lower right corner pixel are approximate; Described the tenth artificial type, represents that described top left corner pixel and lower left corner pixel are approximate; Described the 11 artificial type, represents that described upper right corner pixel and lower right corner pixel are approximate; Described the 12 artificial type, represents that described top left corner pixel and lower right corner pixel are approximate; Described the 13 artificial type, represents that described lower left corner pixel and upper right corner pixel are approximate;

In described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 14 artificial type:

A _r＝A _g,A _g＝A _b

B _r＝B _g,B _g＝B _b

C _r＝C _g,C _g＝C _b

D _r＝D _g,D _g＝D _b

In described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 15 artificial type:

A _g＝0,A _b＝0

B _g＝0,B _b＝0

C _g＝0,C _b＝0

D _g＝0,D _b＝0

In described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 16 artificial type:

A _r＝0,A _b＝0

B _r＝0,B _b＝0

C _r＝0,C _b＝0

D _r＝0,D _b＝0

In described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 17 artificial type:

A _g＝0,A _r＝0

B _g＝0,B _r＝0

C _g＝0,C _r＝0

D _g＝0,D _r＝0

Wherein, A is described top left corner pixel, and B is described upper right corner pixel, and C is described lower left corner pixel, and D is described lower right corner pixel, A _r, A _gbe respectively the red value of pixel A, green numerical value and blue values, B _r, B _gbe respectively the red value of pixel B, green numerical value and blue values, C _r, C _gbe respectively the red value of pixel C, green numerical value and blue values, D _r, D _gbe respectively the red value of pixel D, green numerical value and blue values.

3. image compressing method as claimed in claim 1, it is characterized in that: in described step (B), first judge whether described 2x2 coding unit is in the artificial type of the first artificial type to the three, then judge whether described 2x2 coding unit is in the artificial type of the 4th artificial type to the seven.

4. image compressing method as claimed in claim 2, it is characterized in that, in described step (B), first judge whether described 2x2 coding unit is in the 14 to the 17 artificial type, determine whether again in the artificial type of the first artificial type to the three, determine whether again in the artificial type of the 4th artificial type to the seven, then determine whether in the artificial type of the 8th artificial type to the 13.

5. image compressing method as claimed in claim 3, is characterized in that: in described 2x2 coding unit, every kind of color numerical value adopts 8 bit representations.

6. image compressing method as claimed in claim 5, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the first artificial type:

ABS(A _r,B _r)＜THD1,ABS(C _r,D _r)＜THD1,

ABS(A _g,B _g)＜THD1,ABS(C _g,D _g)＜THD1,

ABS(A _b,B _b)＜THD1,ABS(C _b,D _b)＜THD1,

ABS(A _r,B _r)+ABS(A _g,B _g)+ABS(A _b,B _b)≤

ABS(A _r,C _r)+ABS(A _g,C _g)+ABS(A _b,C _b),

ABS(A _r,B _r)+ABS(A _g,B _g)+ABS(A _b,B _b)≤

ABS(D _r,B _r)+ABS(D _g,B _g)+ABS(D _b,B _b),

ABS(C _r,D _r)+ABS(C _g,D _g)+ABS(C _b,D _b)≤

ABS(D _r,B _r)+ABS(D _g,B _g)+ABS(D _b,B _b),

ABS(C _r,D _r)+ABS(C _g,D _g)+ABS(C _b,D _b)≤

ABS(A _r,C _r)+ABS(A _g,C _g)+ABS(A _b,C _b),

Wherein, THD1 is the first threshold value, and A is described top left corner pixel, and B is described upper right corner pixel, and C is described lower left corner pixel, and D is described lower right corner pixel, A _r, A _g, A _bbe respectively the red value of pixel A, green numerical value and blue values, B _r, B _g, B _bbe respectively the red value of pixel B, green numerical value and blue values, C _r, C _g, C _bbe respectively the red value of pixel C, green numerical value and blue values, D _r, D _g, D _bbe respectively the red value of pixel D, green numerical value and blue values, ABS is the poor absolute value of bracket moderate-element.

7. image compressing method as claimed in claim 5, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the second artificial type:

ABS(A _r,C _r)＜THD1,ABS(B _r,D _r)＜THD1,

ABS(A _g,C _g)＜THD1,ABS(B _g,D _g)＜THD1,

ABS(A _b,C _b)＜THD1,ABS(B _b,D _b)＜THD1,

ABS(A _r,C _r)+ABS(A _g,C _g)+ABS(A _b,C _b)≤

ABS(A _r,B _r)+ABS(A _g,B _g)+ABS(A _b,B _b),

ABS(A _r,C _r)+ABS(A _g,C _g)+ABS(A _b,C _b)≤

ABS(D _r,C _r)+ABS(D _g,C _g)+ABS(D _b,C _b),

ABS(B _r,D _r)+ABS(B _g,D _g)+ABS(B _b,D _b)≤

ABS(D _r,C _r)+ABS(D _g,C _g)+ABS(D _b,C _b),

ABS(B _r,D _r)+ABS(B _g,D _g)+ABS(B _b,D _b)≤

ABS(A _r,B _r)+ABS(A _g,B _g)+ABS(A _b,B _b),

Wherein, THD1 is the first threshold value, and A is described top left corner pixel, and B is described upper right corner pixel, and C is described lower left corner pixel, and D is described lower right corner pixel, A _r, A _g, A _bbe respectively the red value of pixel A, green numerical value and blue values, B _r, B _g, B _bbe respectively the red value of pixel B, green numerical value and blue values, C _r, C _g, C _bbe respectively the red value of pixel C, green numerical value and blue values, D _r, D _g, D _bbe respectively the red value of pixel D, green numerical value and blue values, ABS is the poor absolute value of bracket moderate-element.

8. image compressing method as claimed in claim 5, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 3rd artificial type:

ABS(A _r,D _r)＜THD1,ABS(C _r,B _r)＜THD1,

ABS(A _g,D _g)＜THD1,ABS(C _g,B _g)＜THD1,

ABS(A _b,D _b)＜THD1,ABS(C _b,B _b)＜THD1,

ABS(A _r,D _r)+ABS(A _g,D _g)+ABS(A _b,D _b)≤

ABS(A _r,B _r)+ABS(A _g,B _g)+ABS(A _b,B _b),

ABS(A _r,D _r)+ABS(A _g,D _g)+ABS(A _b,D _b)≤

ABS(D _r,C _r)+ABS(D _g,C _g)+ABS(D _b,C _b),

ABS(C _r,B _r)+ABS(C _g,B _g)+ABS(C _b,B _b)≤

ABS(D _r,C _r)+ABS(D _g,C _g)+ABS(D _b,C _b),

ABS(C _r,B _r)+ABS(C _g,B _g)+ABS(C _b,B _b)≤

ABS(A _r,B _r)+ABS(A _g,B _g)+ABS(A _b,B _b),

Wherein, THD1 is the first threshold value, and A is described top left corner pixel, and B is described upper right corner pixel, and C is described lower left corner pixel, and D is described lower right corner pixel, Ar, A _g, A _bbe respectively the red value of pixel A, green numerical value and blue values, B _r, B _g, B _bbe respectively the red value of pixel B, green numerical value and blue values, C _r, C _g, C _bbe respectively the red value of pixel C, green numerical value and blue values, D _r, D _g, D _bbe respectively the red value of pixel D, green numerical value and blue values, ABS is the poor absolute value of bracket moderate-element.

9. image compressing method as claimed in claim 5, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 4th artificial type:

ABS(B _r,D _r)＜THD2,ABS(C _r,D _r)＜THD2,

ABS(B _g,D _g)＜THD2,ABS(C _g,D _g)＜THD2,

ABS(B _b,D _b)＜THD2,ABS(C _b,D _b)＜THD2,

ABS(B _r,D _r)+ABS(B _g,D _g)+ABS(B _b,D _b)≤

ABS(A _r,C _r)+ABS(A _g,C _g)+ABS(A _b,C _b),

ABS(B _r,D _r)+ABS(B _g,D _g)+ABS(B _b,D _b)≤

ABS(A _r,B _r)+ABS(A _g,B _g)+ABS(A _b,B _b),

ABS(C _r,D _r)+ABS(C _g,D _g)+ABS(C _b,D _b)≤

ABS(A _r,B _r)+ABS(A _g,B _g)+ABS(A _b,B _b),

ABS(C _r,D _r)+ABS(C _g,D _g)+ABS(C _b,D _b)≤

ABS(A _r,C _r)+ABS(A _g,C _g)+ABS(A _b,C _b),

Wherein, THD2 is the second threshold value, and A is described top left corner pixel, and B is described upper right corner pixel, and C is described lower left corner pixel, and D is described lower right corner pixel, A _r, A _g, A _bbe respectively the red value of pixel A, green numerical value and blue values, B _r, B _g, B _bbe respectively the red value of pixel B, green numerical value and blue values, C _r, C _g, C _bbe respectively the red value of pixel C, green numerical value and blue values, D _r, D _g, D _bbe respectively the red value of pixel D, green numerical value and blue values, ABS is the poor absolute value of bracket moderate-element.

10. image compressing method as claimed in claim 5, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 5th artificial type:

ABS(B _r,D _r)＜THD2,ABS(A _r,B _r)＜THD2,

ABS(B _g,D _g)＜THD2,ABS(A _g,B _g)＜THD2,

ABS(B _b,D _b)＜THD2,ABS(A _b,B _b)＜THD2,

ABS(B _r,D _r)+ABS(B _g,D _g)+ABS(B _b,D _b)≤

ABS(A _r,C _r)+ABS(A _g,C _g)+ABS(A _b,C _b),

ABS(B _r,D _r)+ABS(B _g,D _g)+ABS(B _b,D _b)≤

ABS(C _r,D _r)+ABS(C _g,D _g)+ABS(C _b,D _b),

ABS(A _r,B _r)+ABS(A _g,B _g)+ABS(A _b,B _b)≤

ABS(C _r,D _r)+ABS(C _g,D _g)+ABS(C _b,D _b),

ABS(A _r,B _r)+ABS(A _g,B _g)+ABS(A _b,B _b)≤

ABS(A _r,C _r)+ABS(A _g,C _g)+ABS(A _b,C _b),

Wherein, THD2 is the second threshold value, and A is described top left corner pixel, and B is described upper right corner pixel, and C is described lower left corner pixel, and D is described lower right corner pixel, A _r, A _g, A _bbe respectively the red value of pixel A, green numerical value and blue values, B _r, B _g, B _bbe respectively the red value of pixel B, green numerical value and blue values, C _r, C _g, C _bbe respectively the red value of pixel C, green numerical value and blue values, D _r, D _g, D _bbe respectively the red value of pixel D, green numerical value and blue values, ABS is the poor absolute value of bracket moderate-element.

11. image compressing methods as claimed in claim 5, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit makes type as Sixth Man:

ABS(A _r,C _r)＜THD2,ABS(A _r,B _r)＜THD2,

ABS(A _g,C _g)＜THD2,ABS(A _g,B _g)＜THD2,

ABS(A _b,C _b)＜THD2,ABS(A _b,B _b)＜THD2,

ABS(A _r,C _r)+ABS(A _g,C _g)+ABS(A _b,C _b)≤

ABS(B _r,D _r)+ABS(B _g,D _g)+ABS(B _b,D _b),

ABS(A _r,C _r)+ABS(A _g,C _g)+ABS(A _b,C _b)≤

ABS(C _r,D _r)+ABS(C _g,D _g)+ABS(C _b,D _b),

ABS(A _r,B _r)+ABS(A _g,B _g)+ABS(A _b,B _b)≤

ABS(C _r,D _r)+ABS(C _g,D _g)+ABS(C _b,D _b),

ABS(A _r,B _r)+ABS(A _g,B _g)+ABS(A _b,B _b)≤

ABS(B _r,D _r)+ABS(B _g,D _g)+ABS(B _b,D _b),

Wherein, THD2 is the second threshold value, and A is described top left corner pixel, and B is described upper right corner pixel, and C is described lower left corner pixel, and D is described lower right corner pixel, A _r, A _g, A _bbe respectively the red value of pixel A, green numerical value and blue values, B _r, B _g, B _bbe respectively the red value of pixel B, green numerical value and blue values, C _r, C _g, C _bbe respectively the red value of pixel C, green numerical value and blue values, D _r, D _g, D _bbe respectively the red value of pixel D, green numerical value and blue values, ABS is the poor absolute value of bracket moderate-element.

12. image compressing methods as claimed in claim 5, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 7th artificial type:

ABS(A _r,C _r)＜THD2,ABS(C _r,D _r)＜THD2,

ABS(A _g,C _g)＜THD2,ABS(C _g,D _g)＜THD2,

ABS(A _b,C _b)＜THD2,ABS(C _b,D _b)＜THD2,

ABS(A _r,C _r)+ABS(A _g,C _g)+ABS(A _b,C _b)≤

ABS(B _r,D _r)+ABS(B _g,D _g)+ABS(B _b,D _b),

ABS(A _r,C _r)+ABS(A _g,C _g)+ABS(A _b,C _b)≤

ABS(A _r,B _r)+ABS(A _g,B _g)+ABS(A _b,B _b),

ABS(C _r,D _r)+ABS(C _g,D _g)+ABS(C _b,D _b)≤

ABS(A _r,B _r)+ABS(A _g,B _g)+ABS(A _b,B _b),

ABS(C _r,D _r)+ABS(C _g,D _g)+ABS(C _b,D _b)≤

ABS(B _r,D _r)+ABS(B _g,D _g)+ABS(B _b,D _b),

Wherein, THD2 is the second threshold value, and A is described top left corner pixel, and B is described upper right corner pixel, and C is described lower left corner pixel, and D is described lower right corner pixel, A _r, A _g, A _bbe respectively the red value of pixel A, green numerical value and blue values, B _r, B _g, B _bbe respectively the red value of pixel B, green numerical value and blue values, C _r, C _g, C _bbe respectively the red value of pixel C, green numerical value and blue values, D _r, D _g, D _bbe respectively the red value of pixel D, green numerical value and blue values, ABS is the poor absolute value of bracket moderate-element.

13. image compressing methods as claimed in claim 4, is characterized in that: in described 2x2 coding unit, every kind of color numerical value adopts 8 bit representations.

14. image compressing methods as claimed in claim 4, is characterized in that: in described 2x2 coding unit, every kind of color numerical value adopts 6 bit representations.

15. image compressing methods as described in claim 13 or 14, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the first artificial type:

ABS(A _y,B _y)＜THDY1，ABS(C _y,D _y)＜THDY1

ABS(A _u,B _u)＜THDU1，ABS(C _u,D _u)＜THDU1

ABS(A _v,B _v)＜THDV1，ABS(C _v,D _v)＜THDV1

ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)≤ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)≤ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)

ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)≤ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)

ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)≤ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY1 is lightness threshold value 1, and THDU1 is the first colourity threshold value 1, THDV1 is the second colourity threshold value 1, and A is described top left corner pixel, and B is described upper right corner pixel, C is described lower left corner pixel, and D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

16. image compressing methods as described in claim 13 or 14, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the second artificial type:

ABS(A _y,C _y)＜THDY1，ABS(B _y,D _y)＜THDY1

ABS(A _u,C _u)＜THDU1，ABS(B _u,D _u)＜THDU1

ABS(A _v,C _v)＜THDV1，ABS(B _v,D _v)＜THDV1

ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)≤ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)≤ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)

ABS(B _y,D _y)+ABS(B _v,D _v)+ABS(B _u,D _u)≤ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

ABS(B _y,D _y)+ABS(B _v,D _v)+ABS(B _u,D _u)≤ABS(D _y,C _y)+ABS(D _v,C _v)+ABS(D _u,C _u)

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY1 is lightness threshold value 1, and THDU1 is the first colourity threshold value 1, THDV1 is the second colourity threshold value 1, and A is described top left corner pixel, and B is described upper right corner pixel, C is described lower left corner pixel, and D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

17. image compressing methods as described in claim 13 or 14, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 3rd artificial type:

ABS(C _y,B _y)＜THDY1，ABS(A _y,D _y)＜THDY1

ABS(C _u,B _u)＜THDU1，ABS(A _u,D _u)＜THDU1

ABS(C _v,B _v)＜THDV1，ABS(A _v,D _v)＜THDV1

ABS(C _y,B _y)+ABS(C _v,B _v)+ABS(C _u,B _u)≤ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

ABS(C _y,B _y)+ABS(C _v,B _v)+ABS(C _u,B _u)≤ABS(D _y,C _y)+ABS(D _v,C _v)+ABS(D _u,C _u)

ABS(A _y,D _y)+ABS(A _v,D _v)+ABS(A _u,D _u)≤ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

ABS(A _y,D _y)+ABS(A _v,D _v)+ABS(A _u,D _u)≤ABS(D _y,C _y)+ABS(D _v,C _v)+ABS(D _u,C _u)

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY1 is lightness threshold value 1, and THDU1 is the first colourity threshold value 1, THDV1 is the second colourity threshold value 1, and A is described top left corner pixel, and B is described upper right corner pixel, C is described lower left corner pixel, and D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

18. image compressing methods as described in claim 13 or 14, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 4th artificial type:

ABS(D _y,B _y)＜THDY2，ABS(C _y,D _y)＜THDY2

ABS(D _u,B _u)＜THDU2，ABS(C _u,D _u)＜THDU2

ABS(D _v,B _v)＜THDV2，ABS(C _v,D _v)＜THDV2

ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)≤ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)≤ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

ABS(D _y,C _y)+ABS(D _v,C _v)+ABS(D _u,C _u)≤ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

ABS(D _y,C _y)+ABS(D _v,C _v)+ABS(D _u,C _u)≤ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY2 is lightness threshold value 2, and THDU2 is the first colourity threshold value 2, THDV2 is the second colourity threshold value 2, and A is described top left corner pixel, and B is described upper right corner pixel, C is described lower left corner pixel, and D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

19. image compressing methods as described in claim 13 or 14, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 5th artificial type:

ABS(D _y,B _y)＜THDY2，ABS(A _y,B _y)＜THDY2

ABS(D _u,B _u)＜THDU2，ABS(A _u,B _u)＜THDU2

ABS(D _v,B _v)＜THDV2，ABS(A _v,B _v)＜THDV2

ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)≤ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)≤ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)

ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)≤ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)≤ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY2 is lightness threshold value 2, and THDU2 is the first colourity threshold value 2, THDV2 is the second colourity threshold value 2, and A is described top left corner pixel, and B is described upper right corner pixel, C is described lower left corner pixel, and D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

20. image compressing methods as described in claim 13 or 14, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit makes type as Sixth Man:

ABS(A _y,B _y)＜THDY2，ABS(C _y,A _y)＜THDY2

ABS(A _u,B _u)＜THDU2，ABS(C _u,A _u)＜THDU2

ABS(A _v,B _v)＜THDV2，ABS(C _v,A _v)＜THDV2

ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)≤ABS(D _y,C _y)+ABS(D _v,C _v)+ABS(D _u,C _u)

ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)≤ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)

ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)≤ABS(D _y,C _y)+ABS(D _v,C _v)+ABS(D _u,C _u)

ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)≤ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY2 is lightness threshold value 2, and THDU2 is the first colourity threshold value 2, THDV2 is the second colourity threshold value 2, and A is described top left corner pixel, and B is described upper right corner pixel, C is described lower left corner pixel, and D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

21. image compressing methods as described in claim 13 or 14, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 7th artificial type:

ABS(A _y,C _y)＜THDY2，ABS(C _y,D _y)＜THDY2

ABS(A _u,C _u)＜THDU2，ABS(C _u,D _u)＜THDU2

ABS(A _v,C _v)＜THDV2，ABS(C _v,D _v)＜THDV2

ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)≤ABS(B _y,D _y)+ABS(B _v,D _v)+ABS(B _u,D _u)

ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)≤ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

ABS(D _y,C _y)+ABS(D _v,C _v)+ABS(D _u,C _u)≤ABS(B _y,D _y)+ABS(B _v,D _v)+ABS(B _u,D _u)

ABS(D _y,C _y)+ABS(D _v,C _v)+ABS(D _u,C _u)≤ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY2 is lightness threshold value 2, and THDU2 is the first colourity threshold value 2, THDV2 is the second colourity threshold value 2, and A is described top left corner pixel, and B is described upper right corner pixel, C is described lower left corner pixel, and D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

22. image compressing methods as claimed in claim 13, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 8th artificial type:

temp1＝ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

temp2＝ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

temp3＝ABS(A _y,D _y)+ABS(A _v,D _v)+ABS(A _u,D _u)

temp4＝ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)

temp5＝ABS(C _y,B _y)+ABS(C _v,B _v)+ABS(C _u,B _u)

temp6＝ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)

MIN(temp1,temp2,temp3,temp4,temp5,temp6)＝temp1

ABS(A _y,B _y)＜THDY4

ABS(A _v,B _v)＜THDV4

ABS(A _u,B _u)＜THDU4

ABS (C _y, D _y) > THDY3 or ABS (C _v, D _v) > THDV3 or ABS (C _u, D _u) > THDU3

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY3 is lightness threshold value 3, THDU3 is the first colourity threshold value 3, THDV3 is the second colourity threshold value 3, and THDY4 is lightness threshold value 4, and THDU4 is the first colourity threshold value 4, THDV4 is the second colourity threshold value 4, A is described top left corner pixel, and B is described upper right corner pixel, and C is described lower left corner pixel, D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

23. image compressing methods as claimed in claim 13, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 9th artificial type:

temp1＝ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

temp2＝ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

temp3＝ABS(A _y,D _y)+ABS(A _v,D _v)+ABS(A _u,D _u)

temp4＝ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)

temp5＝ABS(C _y,B _y)+ABS(C _v,B _v)+ABS(C _u,B _u)

temp6＝ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)

MIN(temp1,temp2,temp3,temp4,temp5,temp6)＝temp6

ABS(C _y,D _y)＜THDY4

ABS(C _v,D _v)＜THDV4

ABS(C _u,D _u)＜THDU4

ABS (A _y, B _y) > THDY3 or ABS (A _v, B _v) > THDV3 or ABS (A _u, B _u) > THDU3

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY3 is lightness threshold value 3, THDU3 is the first colourity threshold value 3, THDV3 is the second colourity threshold value 3, and THDY4 is lightness threshold value 4, and THDU4 is the first colourity threshold value 4, THDV4 is the second colourity threshold value 4, A is described top left corner pixel, and B is described upper right corner pixel, and C is described lower left corner pixel, D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

24. image compressing methods as claimed in claim 13, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the tenth artificial type:

temp1＝ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

temp2＝ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

temp3＝ABS(A _y,D _y)+ABS(A _v,D _v)+ABS(A _u,D _u)

temp4＝ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)

temp5＝ABS(C _y,B _y)+ABS(C _v,B _v)+ABS(C _u,B _u)

temp6＝ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)

MIN(temp1,temp2,temp3,temp4,temp5,temp6)＝temp2

ABS(A _y,C _y)＜THDY4

ABS(A _v,C _v)＜THDV4

ABS(A _u,C _u)＜THDU4

ABS (B _y, D _y) > THDY3 or ABS (B _v, D _v) > THDV3 or ABS (B _u, D _u) > THDU3

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY3 is lightness threshold value 3, THDU3 is the first colourity threshold value 3, THDV3 is the second colourity threshold value 3, and THDY4 is lightness threshold value 4, and THDU4 is the first colourity threshold value 4, THDV4 is the second colourity threshold value 4, A is described top left corner pixel, and B is described upper right corner pixel, and C is described lower left corner pixel, D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

25. image compressing methods as claimed in claim 13, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 11 artificial type:

temp1＝ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

temp2＝ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

temp3＝ABS(A _y,D _y)+ABS(A _v,D _v)+ABS(A _u,D _u)

temp4＝ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)

temp5＝ABS(C _y,B _y)+ABS(C _v,B _v)+ABS(C _u,B _u)

temp6＝ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)

MIN(temp1,temp2,temp3,temp4,temp5,temp6)＝temp4

ABS(D _y,B _y)＜THDY4

ABS(D _v,B _v)＜THDV4

ABS(D _u,B _u)＜THDU4

ABS (C _y, A _y) > THDY3 or ABS (C _v, A _v) > THDV3 or ABS (C _u, A _u) > THDU3

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY3 is lightness threshold value 3, THDU3 is the first colourity threshold value 3, THDV3 is the second colourity threshold value 3, and THDY4 is lightness threshold value 4, and THDU4 is the first colourity threshold value 4, THDV4 is the second colourity threshold value 4, A is described top left corner pixel, and B is described upper right corner pixel, and C is described lower left corner pixel, D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

26. image compressing methods as claimed in claim 13, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 12 artificial type:

temp1＝ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

temp2＝ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

temp3＝ABS(A _y,D _y)+ABS(A _v,D _v)+ABS(A _u,D _u)

temp4＝ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)

temp5＝ABS(C _y,B _y)+ABS(C _v,B _v)+ABS(C _u,B _u)

temp6＝ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)

MIN(temp1,temp2,temp3,temp4,temp5,temp6)＝temp3

ABS(A _y,D _y)＜THDY4

ABS(A _v,D _v)＜THDV4

ABS(A _u,D _u)＜THDU4

ABS (C _y, B _y) > THDY3 or ABS (C _v, B _v) > THDV3 or ABS (C _u, B _u) > THDU3

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY3 is lightness threshold value 3, THDU3 is the first colourity threshold value 3, THDV3 is the second colourity threshold value 3, and THDY4 is lightness threshold value 4, and THDU4 is the first colourity threshold value 4, THDV4 is the second colourity threshold value 4, A is described top left corner pixel, and B is described upper right corner pixel, and C is described lower left corner pixel, D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

27. image compressing methods as claimed in claim 13, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 13 artificial type:

temp1＝ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

temp2＝ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

temp3＝ABS(A _y,D _y)+ABS(A _v,D _v)+ABS(A _u,D _u)

temp4＝ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)

temp5＝ABS(C _y,B _y)+ABS(C _v,B _v)+ABS(C _u,B _u)

temp6＝ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)

MIN(temp1,temp2,temp3,temp4,temp5,temp6)＝temp5

ABS(C _y,B _y)＜THDY4

ABS(C _v,B _v)＜THDV4

ABS(C _u,B _u)＜THDU4

ABS (A _y, D _y) > THDY3 or ABS (A _v, D _v) > THDV3 or ABS (A _u, D _u) > THDU3

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY3 is lightness threshold value 3, THDU3 is the first colourity threshold value 3, THDV3 is the second colourity threshold value 3, and THDY4 is lightness threshold value 4, and THDU4 is the first colourity threshold value 4, THDV4 is the second colourity threshold value 4, A is described top left corner pixel, and B is described upper right corner pixel, and C is described lower left corner pixel, D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

28. image compressing methods as claimed in claim 14, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 8th artificial type:

temp1＝ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

temp2＝ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

temp3＝ABS(A _y,D _y)+ABS(A _v,D _v)+ABS(A _u,D _u)

temp4＝ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)

temp5＝ABS(C _y,B _y)+ABS(C _v,B _v)+ABS(C _u,B _u)

temp6＝ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)

MIN(temp1,temp2,temp3,temp4,temp5,temp6)＝temp1

ABS(A _y,B _y)＜THDY4

ABS(A _v,B _v)＜THDV4

ABS(A _u,B _u)＜THDU4

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY4 is lightness threshold value 4, and THDU4 is the first colourity threshold value 4, THDV4 is the second colourity threshold value 4, and A is described top left corner pixel, and B is described upper right corner pixel, C is described lower left corner pixel, and D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

29. image compressing methods as claimed in claim 14, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 9th artificial type:

temp1＝ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

temp2＝ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

temp3＝ABS(A _y,D _y)+ABS(A _v,D _v)+ABS(A _u,D _u)

temp4＝ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)

temp5＝ABS(C _y,B _y)+ABS(C _v,B _v)+ABS(C _u,B _u)

temp6＝ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)

MIN(temp1,temp2,temp3,temp4,temp5,temp6)＝temp6

ABS(C _y,D _y)＜THDY4

ABS(C _v,D _v)＜THDV4

ABS(C _u,D _u)＜THDU4

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY4 is lightness threshold value 4, and THDU4 is the first colourity threshold value 4, THDV4 is the second colourity threshold value 4, and A is described top left corner pixel, and B is described upper right corner pixel, C is described lower left corner pixel, and D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

30. image compressing methods as claimed in claim 14, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the tenth artificial type:

temp1＝ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

temp2＝ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

temp3＝ABS(A _y,D _y)+ABS(A _v,D _v)+ABS(A _u,D _u)

temp4＝ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)

temp5＝ABS(C _y,B _y)+ABS(C _v,B _v)+ABS(C _u,B _u)

temp6＝ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)

MIN(temp1,temp2,temp3,temp4,temp5,temp6)＝temp2

ABS(A _y,C _y)＜THDY4

ABS(A _v,C _v)＜THDV4

ABS(A _u,C _u)＜THDU4

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY4 is lightness threshold value 4, and THDU4 is the first colourity threshold value 4, THDV4 is the second colourity threshold value 4, and A is described top left corner pixel, and B is described upper right corner pixel, C is described lower left corner pixel, and D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

31. image compressing methods as claimed in claim 14, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 11 artificial type:

temp1＝ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

temp2＝ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

temp3＝ABS(A _y,D _y)+ABS(A _v,D _v)+ABS(A _u,D _u)

temp4＝ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)

temp5＝ABS(C _y,B _y)+ABS(C _v,B _v)+ABS(C _u,B _u)

temp6＝ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)

MIN(temp1,temp2,temp3,temp4,temp5,temp6)＝temp4

ABS(D _y,B _y)＜THDY4

ABS(D _v,B _v)＜THDV4

ABS(D _u,B _u)＜THDU4

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY4 is lightness threshold value 4, and THDU4 is the first colourity threshold value 4, THDV4 is the second colourity threshold value 4, and A is described top left corner pixel, and B is described upper right corner pixel, C is described lower left corner pixel, and D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

32. image compressing methods as claimed in claim 14, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 12 artificial type:

temp1＝ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

temp2＝ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

temp3＝ABS(A _y,D _y)+ABS(A _v,D _v)+ABS(A _u,D _u)

temp4＝ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)

temp5＝ABS(C _y,B _y)+ABS(C _v,B _v)+ABS(C _u,B _u)

temp6＝ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)

MIN(temp1,temp2,temp3,temp4,temp5,temp6)＝temp3

ABS(A _y,D _y)＜THDY4

ABS(A _v,D _v)＜THDV4

ABS(A _u,D _u)＜THDU4

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY4 is lightness threshold value 4, and THDU4 is the first colourity threshold value 4, THDV4 is the second colourity threshold value 4, and A is described top left corner pixel, and B is described upper right corner pixel, C is described lower left corner pixel, and D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

33. image compressing methods as claimed in claim 14, is characterized in that: in described step (B), in the time meeting following formula, judge that described 2x2 coding unit is as the 13 artificial type:

temp1＝ABS(A _y,B _y)+ABS(A _v,B _v)+ABS(A _u,B _u)

temp2＝ABS(A _y,C _y)+ABS(A _v,C _v)+ABS(A _u,C _u)

temp3＝ABS(A _y,D _y)+ABS(A _v,D _v)+ABS(A _u,D _u)

temp4＝ABS(D _y,B _y)+ABS(D _v,B _v)+ABS(D _u,B _u)

temp5＝ABS(C _y,B _y)+ABS(C _v,B _v)+ABS(C _u,B _u)

temp6＝ABS(C _y,D _y)+ABS(C _v,D _v)+ABS(C _u,D _u)

MIN(temp1,temp2,temp3,temp4,temp5,temp6)＝temp5

ABS(C _y,B _y)＜THDY4

ABS(C _v,B _v)＜THDV4

ABS(C _u,B _u)＜THDU4

Wherein, ABS is the poor ABS function of two elements in bracket, and THDY4 is lightness threshold value 4, and THDU4 is the first colourity threshold value 4, THDV4 is the second colourity threshold value 4, and A is described top left corner pixel, and B is described upper right corner pixel, C is described lower left corner pixel, and D is described lower right corner pixel, A _y, A _u, A _vbe respectively lightness, the first colourity and second chromatic value of pixel A, B _y, B _u, B _vbe respectively lightness, the first colourity and second chromatic value of pixel B, C _y, C _u, C _vbe respectively lightness, the first colourity and the second chromatic value of pixel C, D _y, D _u, D _vbe respectively lightness, the first colourity and the second chromatic value of pixel D;

Wherein, described lightness, the first colourity and the second chromatic value carry out RGB to YUV color gamut conversion by following formula and obtain:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, the green value that g is this pixel, the blue valve that b is this pixel, the lightness that Y is this pixel, the colourity that U and V are this pixel.

34. image compressing methods as described in claim 5,13 or 14, is characterized in that: in step (D), by carrying out RGB to YUV color gamut conversion, to obtain described 2x2 gamut conversion unit, described RGB to YUV color gamut conversion is shown with following formula table:

$\left[\begin{array}{c}Y\\ U\\ V\end{array}\right]=\left[\begin{array}{ccc}0.25& 0.5& 0.25\\ -0.5& 1.0& -0.5\\ -1.0& 0& 1.0\end{array}\right]\left[\begin{array}{c}r\\ g\\ b\end{array}\right],$

Wherein, r is the red value of a pixel, g is the green value of this pixel, b is the blue valve of this pixel, Y is the lightness of this pixel, U and V are the colourity of this pixel, and described 2x2 gamut conversion unit is divided into lightness 2x2 gamut conversion unit (Y), the first colourity 2x2 gamut conversion unit (U) and the second colourity 2x2 gamut conversion unit (V).

35. image compressing methods as claimed in claim 34, is characterized in that: in step (E), described discrete cosine transform is shown with following formula table:

$\left[\begin{array}{c}E\\ F\\ G\\ H\end{array}\right]=0.25\&times;\left[\begin{array}{cccc}1& 1& 1& 1\\ 1& -1& 1& -1\\ 1& 1& -1& -1\\ 1& -1& -1& 1\end{array}\right]\left[\begin{array}{c}\stackrel{\&OverBar;}{A}\\ \stackrel{\&OverBar;}{B}\\ \stackrel{\&OverBar;}{C}\\ \stackrel{\&OverBar;}{D}\end{array}\right],$

Wherein, for the upper left corner value of described 2x2 gamut conversion unit, for the upper right corner value of described 2x2 gamut conversion unit, for the lower left corner value of described 2x2 gamut conversion unit, for the lower right corner value of described 2x2 gamut conversion unit, E element is the upper left corner value of described 2x2 frequency domain unit, F element is the upper right corner value of described 2x2 frequency domain unit, G element is the lower left corner value of described 2x2 frequency domain unit, H element is the lower right corner value of described 2x2 frequency domain unit, and described 2x2 frequency domain unit is divided into lightness 2x2 frequency domain unit, the first colourity 2x2 frequency domain unit and the second colourity 2x2 frequency domain unit.

36. image compressing methods as described in claim 5 or 14, is characterized in that: between described step (E) and step (F), also comprise step:

(H) described 2x2 frequency domain unit is divided into the first natural type or the second nature type, wherein, when F element and G element in described the first colourity 2x2 frequency domain unit (U) meet following formula:

max(ABS(F,0),ABS(G,0))≤THD3，

And F element and G element in described the second colourity 2x2 frequency domain unit (V) meet following formula:

max(ABS(F,0),ABS(G,0))≤THD4，

Judge that this 2x2 frequency domain unit is as described the first natural type, otherwise, judge that this 2x2 frequency domain unit is as described the second nature type, wherein, THD3 is the 3rd threshold value, THD4 is the 4th threshold value;

Wherein, F element is the upper right corner value of described 2x2 frequency domain unit, and G element is the lower left corner value of described 2x2 frequency domain unit.

37. image compressing methods as claimed in claim 13, is characterized in that: between described step (E) and step (F), also comprise step:

Described 2x2 frequency domain unit is divided into the first natural type, the second nature type or Third Nature type by (H '), wherein,

When the H element of the first colourity 2x2 frequency domain unit (U) meets following formula,

H＞THD1

Judge that described 2x2 coding unit is as the first natural type;

When F element and G element in the first colourity 2x2 frequency domain unit (U) meet following formula,

MAX(ABS(F,0),ABS(G,0))≤THD2

And F element and G element in the second colourity 2x2 frequency domain unit (V) meet following formula,

MAX(ABS(F,0),ABS(G,0))≤THD3

Judge that described 2x2 coding unit is as the second nature type;

Do not meet the first natural type and the second nature type condition, judge that described 2x2 coding unit is as Third Nature type;

Wherein, THD1 is the first threshold value, and THD2 is the second threshold value, THD3 is the 3rd threshold value, F element is the upper right corner value of described 2x2 frequency domain unit, and G element is the lower left corner value of described 2x2 frequency domain unit, and H element is the lower right corner value of described 2x2 frequency domain unit.

38. image compressing methods as claimed in claim 5, is characterized in that: in step (C), in the time that described 2x2 coding unit is the first artificial type, the second artificial type or the 3rd artificial type, use the wherein mean value of two pixels of 8 records; Use 7 record one 7 bit table cases to put, the content that records that described 7 bit table cases are put is: all record in content in these 7 bit table lattice, differs reckling with the difference of the mean value of other two pixels in this 2x2 coding unit and the mean value of aforesaid two pixels.

39. image compressing methods as claimed in claim 5, it is characterized in that: in step (C), when 2x2 coding unit is that the 4th artificial type, the 5th artificial type, Sixth Man are while making type or the 7th artificial type, use the wherein mean value of three pixels of 8 records, use 7 or 6 quantized values that record another one pixel in this 2x2 coding unit.

40. image compressing methods as claimed in claim 5, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the first natural type, use 7 E element, F element and G elements that record in described lightness 2x2 frequency domain unit; Use 4 record one 4 bit table cases to put, the content that records that described 4 bit table cases are put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the value of the H element in this lightness 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit, and F element is the upper right corner value of described 2x2 frequency domain unit, and G element is the lower left corner value of described 2x2 frequency domain unit, and H element is the lower right corner value of described 2x2 frequency domain unit.

41. image compressing methods as claimed in claim 5, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the first natural type, use 7 E elements that record in described the first colourity 2x2 frequency domain unit; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the mean value of F element in this first colourity 2x2 frequency domain unit and G element; Do not record the H element in this first colourity 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit, and F element is the upper right corner value of described 2x2 frequency domain unit, and G element is the lower left corner value of described 2x2 frequency domain unit, and H element is the lower right corner value of described 2x2 frequency domain unit.

42. image compressing methods as claimed in claim 5, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the first natural type, use 7 E elements that record in described the second colourity 2x2 frequency domain unit; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the mean value of F element in this second colourity 2x2 frequency domain unit and G element; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the H element of this second colourity 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit, and F element is the upper right corner value of described 2x2 frequency domain unit, and G element is the lower left corner value of described 2x2 frequency domain unit, and H element is the lower right corner value of described 2x2 frequency domain unit.

43. image compressing methods as claimed in claim 5, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the second nature type, use 6 quantized values that record the E element in described lightness 2x2 frequency domain unit; Use 5 quantized values that record the F element of described lightness 2x2 frequency domain unit; Use 5 quantized values that record the G element of described lightness 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the H element of this lightness 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit, and F element is the upper right corner value of described 2x2 frequency domain unit, and G element is the lower left corner value of described 2x2 frequency domain unit, and H element is the lower right corner value of described 2x2 frequency domain unit.

44. image compressing methods as claimed in claim 5, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the second nature type, use 5 quantized values that record the E element in described the first colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the F element in this first colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the G element in this first colourity 2x2 frequency domain unit; Do not record the H element of this first colourity 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit, and F element is the upper right corner value of described 2x2 frequency domain unit, and G element is the lower left corner value of described 2x2 frequency domain unit, and H element is the lower right corner value of described 2x2 frequency domain unit.

45. image compressing methods as claimed in claim 5, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the second nature type, use 5 quantized values that record the E element in described the second colourity 2x2 frequency domain unit; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the F element in this second colourity 2x2 frequency domain unit; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the G element in this second colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the H element in this second colourity 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit, and F element is the upper right corner value of described 2x2 frequency domain unit, and G element is the lower left corner value of described 2x2 frequency domain unit, and H element is the lower right corner value of described 2x2 frequency domain unit.

46. image compressing methods as claimed in claim 13, it is characterized in that: in step (C), when described 2x2 coding unit is the first artificial type, when the second artificial type and the 3rd artificial type, use the wherein mean value of two pixels of 8 records, use one 6 of 6 or 7 records or 7 bit table cases to put, the content that records that these 6 or 7 bit table cases are put is: these 6 or all of 7 bit table lattice record in content, the difference of the mean value of two pixels that record with mean value and 8 of the aforesaid uses of other two pixels in this 2x2 coding unit differs reckling.

47. image compressing methods as claimed in claim 13, it is characterized in that: in step (C), in the time that described 2x2 coding unit is the 4th artificial type to the seven artificial type, use the wherein mean value of three pixels of 8 records, use 7 or 6 quantized values that record another one pixel in described 2x2 coding unit.

48. image compressing methods as claimed in claim 13, it is characterized in that: in step (C), in the time that described 2x2 coding unit is the 8th artificial type to the 13 artificial type, use the wherein quantized value of two pixel average of 5 records, use 4 quantized values that record respectively all the other two pixels; Or use the wherein quantized value of two pixel average of 7 records, use 5 quantized values that record all the other two pixels.

49. image compressing methods as claimed in claim 13, is characterized in that: in step (C), in the time that described 2x2 coding unit is the 14 artificial type to the 17 artificial type, uses 8 pixel data is carried out to complete record.

50. image compressing methods as claimed in claim 37, it is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the first natural type, use the quantized value of 5 E elements that record lightness 2x2 frequency domain unit, F element, G element; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the difference reckling of the value of the H element of described lightness 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit.

51. image compressing methods as claimed in claim 37, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the first natural type, use the quantized value of the E element of 5 record the first colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the difference reckling of the value of the F element of described the first colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the difference reckling of the value of the G element of described the first colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the difference reckling of the value of the H element of described the first colourity 2x2 frequency domain unit 770; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit.

52. image compressing methods as claimed in claim 37, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the first natural type, use the quantized value of the E element of 5 record the second colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the difference reckling of the value of the F element of described the second colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the difference reckling of the value of the G element of described the second colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the difference reckling of the value of the H element of described the second colourity 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit.

53. image compressing methods as claimed in claim 37, it is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the second nature type, use the quantized value of 7 E elements that record lightness 2x2 frequency domain unit, F element, G element; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the difference reckling of the value of the H element of described lightness 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit.

54. image compressing methods as claimed in claim 37, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the second nature type, use the quantized value of the E element of 6 record the first colourity 2x2 frequency domain unit; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the described first F element of colourity 2x2 frequency domain unit and the mean value of G element; Do not record the H element of described the first colourity 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit.

55. image compressing methods as claimed in claim 37, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the second nature type, use the quantized value of the E element of 7 record the second colourity 2x2 frequency domain unit; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the mean value of F element in described the second colourity 2x2 frequency domain unit and G element; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the H element of described the second colourity 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit.

56. image compressing methods as claimed in claim 37, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is Third Nature type, use 5 quantized values that record the E element of lightness 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the F element of described lightness 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the G element of described lightness 2x2 frequency domain unit; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the value of the H element of described lightness 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit.

57. image compressing methods as claimed in claim 37, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is Third Nature type, use the quantized value of the E element of 4 record the first colourity 2x2 frequency domain unit; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the value of the F element of described the first colourity 2x2 frequency domain unit; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the value of the G element of described the first colourity 2x2 frequency domain unit; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the value of the H element of described the first colourity 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit.

58. image compressing methods as claimed in claim 37, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is Third Nature type, use the quantized value of the E element of 4 record the second colourity 2x2 frequency domain unit; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the value of the F element of described the second colourity 2x2 frequency domain unit; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the value of the G element of described the second colourity 2x2 frequency domain unit; Use 4 record one 4 bit table cases to put, the content that records that this 4 bit table case is put is: all of these 4 bit table lattice record in content, with the reckling in the difference of the value of the H element of described the second colourity 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit.

59. image compressing methods as claimed in claim 5, is characterized in that: described 2x2 coding unit is 96, and the coding package of described 2x2 coding unit is 48.

60. image compressing methods as claimed in claim 14, it is characterized in that: in step (C), in the time that described 2x2 coding unit is the first artificial type, the second artificial type or the 3rd artificial type, use the wherein mean value of two pixels of 6 records; Use one 5 of 5 or 4 records or 4 bit table cases to put, the content that records that described 5 or 4 bit table cases are put is: all record in content in these 5 or 4 bit table lattice, differs reckling with the difference of the mean value of other two pixels in this 2x2 coding unit and the mean value of aforesaid two pixels.

61. image compressing methods as claimed in claim 14, it is characterized in that: in step (C), when 2x2 coding unit is that the 4th artificial type, the 5th artificial type, Sixth Man are while making type or the 7th artificial type, use the wherein mean value of three pixels of 6 records, use 5 or 4 quantized values that record another one pixel in this 2x2 coding unit.

62. image compressing methods as claimed in claim 14, it is characterized in that: in step (C), in the time that 2x2 coding unit is the 8th artificial type to the 13 artificial type, use 5 or the wherein quantized value of two close pixel average of 4 records, use respectively 3 quantized values that record another two pixels.

63. image compressing methods as claimed in claim 14, is characterized in that: in step (C), in the time that 2x2 coding unit is the 14 artificial type to the 17 artificial type, uses 6 pixel data is carried out to complete record.

64. image compressing methods as claimed in claim 14, it is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the first natural type, use 5 quantized values that record E element, F element and G element in described lightness 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that described 3 bit table cases are put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the value of the H element in this lightness 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit, and F element is the upper right corner value of described 2x2 frequency domain unit, and G element is the lower left corner value of described 2x2 frequency domain unit, and H element is the lower right corner value of described 2x2 frequency domain unit.

65. image compressing methods as claimed in claim 14, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the first natural type, use 5 quantized values that record the E element in described the first colourity 2x2 frequency domain unit; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the mean value of F element in this first colourity 2x2 frequency domain unit and G element; Do not record the H element in this first colourity 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit, and F element is the upper right corner value of described 2x2 frequency domain unit, and G element is the lower left corner value of described 2x2 frequency domain unit, and H element is the lower right corner value of described 2x2 frequency domain unit.

66. image compressing methods as claimed in claim 14, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the first natural type, use 5 quantized values that record the E element in described the second colourity 2x2 frequency domain unit; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the mean value of F element in this second colourity 2x2 frequency domain unit and G element; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the H element of this second colourity 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit, and F element is the upper right corner value of described 2x2 frequency domain unit, and G element is the lower left corner value of described 2x2 frequency domain unit, and H element is the lower right corner value of described 2x2 frequency domain unit.

67. image compressing methods as claimed in claim 14, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the second nature type, use 4 quantized values that record the E element in described lightness 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the F element of this lightness 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the G element of this lightness 2x2 frequency domain unit; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the H element of this lightness 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit, and F element is the upper right corner value of described 2x2 frequency domain unit, and G element is the lower left corner value of described 2x2 frequency domain unit, and H element is the lower right corner value of described 2x2 frequency domain unit.

68. image compressing methods as claimed in claim 14, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the second nature type, use 3 quantized values that record the E element in described the first colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the F element in this first colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the G element in this first colourity 2x2 frequency domain unit; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the H element of this lightness 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit, and F element is the upper right corner value of described 2x2 frequency domain unit, and G element is the lower left corner value of described 2x2 frequency domain unit, and H element is the lower right corner value of described 2x2 frequency domain unit.

69. image compressing methods as claimed in claim 14, is characterized in that: in step (F), in the time that described 2x2 frequency domain unit is the second nature type, use 3 quantized values that record the E element in described the first colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the F element in this first colourity 2x2 frequency domain unit; Use 3 record one 3 bit table cases to put, the content that records that this 3 bit table case is put is: all of these 3 bit table lattice record in content, with the reckling in the difference of the G element in this first colourity 2x2 frequency domain unit; Use 2 record one 2 bit table cases to put, the content that records that this 2 bit table case is put is: all of these 2 bit table lattice record in content, with the reckling in the difference of the H element of this lightness 2x2 frequency domain unit; Wherein, E element is the upper left corner value of described 2x2 frequency domain unit, and F element is the upper right corner value of described 2x2 frequency domain unit, and G element is the lower left corner value of described 2x2 frequency domain unit, and H element is the lower right corner value of described 2x2 frequency domain unit.

70. image compressing methods as claimed in claim 14, is characterized in that: described 2x2 coding unit is 72, and the coding package of described 2x2 coding unit is 36.

The 71. 1 kinds of image compression with fixing compression ratio, decompression systems based on 2x2 coding unit, is characterized in that, described system comprises:

One display module, for showing described image;

One image input equipment, for inputting described image;

One fixing compression ratio image compression device based on 2x2 coding unit, is connected to described image input equipment, for this image is encoded, to generate coding package;

One apparatus for temporary storage, is connected to the described fixing compression ratio image compression device based on 2x2 coding unit, for described coding package;

One fixing compression ratio image decompressing device based on 2x2 coding unit, is connected to described apparatus for temporary storage, for receiving described coding package, and this coding package is decompressed, to produce the 2x2 decoding unit corresponding with described 2x2 coding unit; And

Time schedule controller, is connected to the described fixing compression ratio image decompressing device based on 2x2 coding unit, and for receiving described 2x2 decoding unit, the sequential that produces described display module drives signal and shows data,

Wherein, described fixing compression ratio image compression device first judges that described 2x2 coding unit is artificial type or natural type, with the coding that carries out differential errors coding, quantizes and table look-up of the 2x2 coding unit to this artificial type, and then generation first coding data, and to the 2x2 coding unit of this natural type coding that carries out color gamut conversion, discrete cosine transform, quantizes and table look-up, and then generation the second coded data, again this first coding data or this second coded data are encapsulated, to produce the coding package with fixing compression ratio;

Wherein, described artificial type comprises the first to the 7th artificial type; Wherein the first artificial type list shows wherein four pixels, two horizontal stripes in horizontal direction, and top left corner pixel and upper right corner pixel are approximate, and lower left corner pixel and lower right corner pixel approximate; The second artificial type represents that wherein four pixels are two vertical stripes of vertical direction, and top left corner pixel and lower left corner pixel are approximate, and upper right corner pixel and lower right corner pixel approximate; The 3rd artificial type represents that wherein the two slanted bar lines that four pixels are miter angle direction intersect, and top left corner pixel and lower right corner pixel are approximate, and lower left corner pixel and upper right corner pixel approximate; The the 4th to the 7th artificial type represents wherein the combination with single-point triangular in shape of four pixels; I.e. the 4th artificial type, represents that lower left corner pixel, upper right corner pixel and lower right corner pixel are approximate; The 5th artificial type, represents that top left corner pixel, upper right corner pixel and lower right corner pixel are approximate; Sixth Man is made type, represents that top left corner pixel, lower left corner pixel and upper right corner pixel are approximate; The 7th artificial type, represents that top left corner pixel, lower left corner pixel and lower right corner pixel are approximate.

72. 1 kinds of image decompression methods with fixing compression ratio based on 2x2 coding unit, it is characterized in that: a coding package is decoded, with the 2x2 decoding unit in reconstructed image, described 2x2 decoding unit comprises four pixels that are matrix arrangement, at least one 2x2 decoding unit forms described image, and described image decompression method comprises the following steps:

(A) receive described coding package;

(B) judge according to the main packet header of this coding package whether this coding package is artificial type, if so, judge that this coding package is behaved to make the coding package of type, otherwise, judge the coding package that this coding package is natural type;

(C) the coding package of this artificial type is carried out to inverse quantization, counter table look-up decoding and contrast point error decoding, to produce the first decoded data;

(D) the coding package of this natural type is carried out to inverse quantization and the anti-decoding of tabling look-up, to produce the second decoded data;

(E) this second decoded data is carried out to discrete cosine transform, to produce the 3rd decoded data;

(F) the 3rd decoded data is carried out to color gamut conversion, to obtain the 4th decoded data; And

(G) receive described the first decoded data or the 4th decoded data, and the first decoded data or the 4th decoded data are rebuild, to produce 2x2 decoding unit;

Wherein, described artificial type comprises the first to the 7th artificial type; Wherein the first artificial type list shows wherein four pixels, two horizontal stripes in horizontal direction, and top left corner pixel and upper right corner pixel are approximate, and lower left corner pixel and lower right corner pixel approximate; The second artificial type represents that wherein four pixels are two vertical stripes of vertical direction, and top left corner pixel and lower left corner pixel are approximate, and upper right corner pixel and lower right corner pixel approximate; The 3rd artificial type represents that wherein the two slanted bar lines that four pixels are miter angle direction intersect, and top left corner pixel and lower right corner pixel are approximate, and lower left corner pixel and upper right corner pixel approximate; The the 4th to the 7th artificial type represents wherein the combination with single-point triangular in shape of four pixels; I.e. the 4th artificial type, represents that lower left corner pixel, upper right corner pixel and lower right corner pixel are approximate; The 5th artificial type, represents that top left corner pixel, upper right corner pixel and lower right corner pixel are approximate; Sixth Man is made type, represents that top left corner pixel, lower left corner pixel and upper right corner pixel are approximate; The 7th artificial type, represents that top left corner pixel, lower left corner pixel and lower right corner pixel are approximate.

73. image decompression methods as described in claim 72, is characterized in that, further comprising the steps of in step (B):

(H) in the time being judged to be the coding package of artificial type, judge according to the sub-packet header in described coding package whether it is in the artificial type of the first artificial type to the three, wherein, described the first artificial type is two vertical stripes that described four pixels are vertical direction, the second artificial type is two vertical stripes that described four pixels are vertical direction, and the 3rd artificial type is the two slanted bar lines intersections that described four pixels are miter angle direction; And

(I) otherwise, judge according to this sub-packet header of this coding package and second son packet header whether it is in the artificial type of the 4th artificial type to the seven again, wherein, the artificial type of described the 4th artificial type to the seven is the combinations with single-point triangular in shape of described four pixels.

74. image decompression methods as described in claim 72, is characterized in that: between step (C) and step (D), further comprising the steps of:

(J) for the coding package of described natural type, judge that according to the sub-packet header of this coding package it is the first natural type or the second nature type.

75. image decompression methods as described in claim 74, is characterized in that: in step (E), the transition matrix coefficient of described discrete cosine transform is:

$\left[\begin{array}{c}\stackrel{\&OverBar;}{A}\\ \stackrel{\&OverBar;}{B}\\ \stackrel{\&OverBar;}{C}\\ \stackrel{\&OverBar;}{D}\end{array}\right]=\left[\begin{array}{cccc}1& 1& 1& 1\\ 1& -1& 1& -1\\ 1& 1& -1& -1\\ 1& -1& -1& 1\end{array}\right]\left[\begin{array}{c}E\\ F\\ G\\ H\end{array}\right],$

Wherein, E, F, G, H are described the second decoded data, for described the 3rd decoded data.

76. image decompression methods as described in claim 75, is characterized in that: in step (F), carry out YUV to RGB color gamut conversion, the transition matrix coefficient of described YUV to RGB color gamut conversion is:

$\left[\begin{array}{c}r\\ g\\ b\end{array}\right]=\left[\begin{array}{ccc}1.0& -0.5& -0.5\\ 1.0& 0.5& 0\\ 1.0& -0.5& 0.5\end{array}\right]\left[\begin{array}{c}Y\\ U\\ V\end{array}\right],$

Wherein, Y is the lightness of the pixel in described the 3rd decoded data, the colourity that U and V are this pixel; R is the red value of the pixel in the 4th decoded data, the green value that g is this pixel, the blue valve that b is this pixel.