JPS6253107B2 - - Google Patents
Info
- Publication number
- JPS6253107B2 JPS6253107B2 JP56195940A JP19594081A JPS6253107B2 JP S6253107 B2 JPS6253107 B2 JP S6253107B2 JP 56195940 A JP56195940 A JP 56195940A JP 19594081 A JP19594081 A JP 19594081A JP S6253107 B2 JPS6253107 B2 JP S6253107B2
- Authority
- JP
- Japan
- Prior art keywords
- luminance signal
- pixel
- signal
- bits
- residual
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000034 method Methods 0.000 claims description 14
- 238000013139 quantization Methods 0.000 claims description 11
- 238000010586 diagram Methods 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000009978 visual deterioration Effects 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/40—Picture signal circuits
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Image Input (AREA)
- Image Processing (AREA)
- Facsimile Image Signal Circuits (AREA)
Description
本発明は、画像の輝度信号の量子化方法に関
し、１画素当りのビツト数を画質劣化を殆んど伴
わずに減少させることを目的とする。
本発明によれば中間調を表現しうる写真フイル
ムなどの媒体においては、画像情報を量子化し、
これをもとに露光する場合に、１画素当りの露光
量情報を荷うビツト数を、画質劣化を殆んど伴わ
ずに減少させることができる。網点写真において
は、１網点内のドツト数を著しく減少させ、かつ
階調特性を保ちつつ、解像力を増加させることが
できる。
従来より、２値の輝度を表現し得る媒体を用い
て、中間調画像を表現する場合、デイザ法に類す
る方法と網点写真方法とが知られている。テイザ
法においては、１画素１ビツトで画素のもつ輝度
を表現し、輝度誤差をその画素の近傍の２個以上
の画素にふり当てることが知られている。しかし
従来のデイザ法においては、織目状ノイズが目立
ち、一方網点写真法においては、解像力が十分で
ない。
中間調を含む画像を走査読取りし、得られる輝
度信号を量子化し、記憶装置との間で、記憶・再
生をおこなう場合、或いは又画像情報をデジタル
伝送する場合、十分な画質を得るには、１画素当
り８ビツト（256階調）〜６ビツト（64階調）は
必要である。この十分な画質を得るに必要な１画
素当りのビツト数をｍビツトとする。本発明によ
れば、輪郭、主要階調は、当該画素においてｎビ
ツト（ｎ＜ｍ）で表現し、わずかの残余値の階調
は、周辺画素、特に当該画素の次に処理される画
素とで分担する。これにより、１画素当りに割当
てるビツト数をｎ＝２〜４に減少させても視覚画
質は殆んど劣化しない。
以下に図面を用いて本発明の一実施例を説明す
る。第１図は、本発明を用いたシステムのブロツ
ク系統図である。１は走査読取装置で、これで読
取つた画像のアナログ輝度信号を、量子化装置２
で量子化する。
３は磁気デイスクなどの記憶装置で、量子化装
置２で量子化された画像信号は、ここに蓄えら
れ、必要に応じて読出される。４はデジタル・ア
ナログ変換装置で、読み出した量子化画像信号を
アナログ信号に変換し、記録装置５にて印画し、
原画を復元する。なお、記憶装置３はフアクシミ
リの伝送線に置き換えることもできる。この場
合、走査読取装置１、量子化装置２は送信端末、
デジタル・アナログ変換装置４、記録装置５は受
信端末となる。更にデジタル・アナログ・変換装
置４は、デジタル信号を印画紙に輝度情報として
与える変換装置ではなく、網点信号を発生させる
ための装置と考えてもよい。
第２図は第１図に示した量子化装置２の詳細ブ
ロツク図である。ｍビツトに量子化を行うｍビツ
ト量子化装置２１は、信号線２１Ａを通してアナ
ログの読取り輝度信号を受取り、ｍビツトのデジ
タルの読取り輝度信号に量子化する。なお、輪郭
強調、階調補正など、必要ならば、このブロツ
ク、すなわちｍビツト量子化装置２１で行う。
次に、ｍビツト量子化装置２１で行なわれたｍ
ビツトのデジタルの読取り輝度信号は線２１Ａを
介して、ｎビツト量子化装置２２に送出され、第
３図に示すような画素に対して次のようなｎビツ
トの輝度信号を作る。
なお、第３図において、升目は画素を示し矢印
３１は第１図に示した読取装置１の主走査方向、
矢印３２は副走査方向を示す。また印の画素３
４は現在処理中の画素、画素３３は画素３４の１
つ前に処理された画素、画素３５は画素３４の１
つ後に処理される画素である。
さて、第３図に示すように、後述する画素３３
の残余輝度信号（ｍ−ｎビツト）をｈ３３とする
と、画素３４のｍビツトの読取り輝度信号ｂ３４
に、残余輝度信号装置２３より線２３Ａを介して
読み出した画素３３の残余輝度信号ｈ３３を加え
て総合輝度信号ｔ３４を生成する。
そしてこのｍビツトの総合輝度信号ｔ３４か
ら、上位ｎビツトまでの値を画素３４の最終的な
輝度信号Ｂ３４とする。一方、総合輝度信号ｔ３
４の下位（ｍ−ｎ）ビツト画素３４の残余輝度信
号ｈ３４とし、この残余輝度信号ｈ３４を線２２
Ａを介して残余輝度信号装置２３に送り記憶させ
る。なお、この残余輝度信号ｈ３４は次の画素３
５を処理するときに残余輝度信号として用いられ
る。
さて、ｍビツト総合輝度信号ｔ３４から、画素
３４の最終的ｎビツトの輝度信号を生成する方法
としては、
(A) 上述したように、ｍビツトの総合輝度信号ｔ
３４の上位からｎビツトを用いて当該画素３４
の最終的輝度信号Ｂ３４とし、残りの（ｍ−
ｎ）ビツト、すなわち総合輝度信号ｔ３４の下
位から（ｍ−ｎ）ビツトを用いて、次の画素３
５を処理するための残余輝度信号ｈ３４とする
場合の他に、
(B) 上記(A)の処理をした上で、さらに当該画素３
４のｎビツト最終的輝度信号Ｂ３４のLSB（最
下位ビツト）に＋１をする場合がある。＋１し
た場合はこの＋１が誤差となるため、残余輝度
信号ｈ３４に反映させる必要がある。そのた
め、総合輝度信号ｔ３４から最終的輝度信号ｈ
３４を減じたものを残余輝度信号ｈ３４とする
ので、この残余輝度信号ｈ３４は負の値とな
る。
以下、上記(A)、(B)の具体的な実施例を説明す
る。(A)の場合
読取り輝度信号、総合輝度信号のビツト数を
８、すなわちｍ＝８、残余輝度信号のビツト数を
５、すなわちｍ−ｎ＝５、
これにより最終的な輝度信号のビツト数３、す
なわちｎ＝３とし、今処理しようとしている読取
り輝度信号の値を179（但し、輝度信号の範囲を
０〜255とする）とし、直前に処理された残余輝
度信号の値を25（但し、輝度信号の範囲を同じく
０〜255とする）とすると、ｍビツト量子化装置
２１の出力、及び残余輝度信号記憶装置２３の記
憶状態は共に２進数で表現されているため、
読取り輝度信号b34＝10110011 ……(1)
残余輝度信号h33＝00010101 ……(2)
と表現され、総合輝度信号ｔ３４は、
総合輝度信号t34＝読取り輝度信号b34
＋残余輝度信号h33 ……(3)
であらわせるため、上記第１、２式より、第３式
は、
総合輝度信号t34＝10110011
＋00010101＝11001000 ……(4)
さらに、最終的輝度信号Ｂ３４は総合輝度信号
ｔ３４の上位３ビツトまでを用いるため、上記第
４式より、
最終的輝度信号B34＝110 ……(5)
また、次の画素３５を処理するときに利用され
る残余輝度信号ｈ３４は下位から（８−３）ビツ
ト、すなわち５ビツトまでを用いるため、上記第
４式より、
残余輝度信号h34＝00001000 ……(6)
となる。
(B)の場合
上記(A)の処理をした上で、さらに当該画素３４
のｎビツトの最終的輝度信号Ｂ３４のLSBに＋１
をするため上記第５式より
最終的輝度信号B34＝110＋001＝111 ……(7)
となり、また残余輝度信号ｈ３４は、
残余輝度信号h34＝総合輝度信号t34
−最終的輝度信号B34 ……(8)
であらわせるため、上記第４、８式より、
残余輝度信号h34＝11010000
−11100000＝−00010000 ……(9)
となる。
以上のようにして生成された画素あたりｎビツ
トの最終的輝度信号は線２２Ｂを介して、第１図
に示した記憶装置３に送られ、記憶される。
次に、上記(A)により中間調画像を処理した場合
のその効果を具体的に示す。
下記表は直線的に変化する10画素の信号を従来
のままで３ビツトの量子化を実施する場合と、本
発明の一実施例における上記(A)の方法、すなわち
残余輝度信号を次画素に反映する場合とのその誤
差を比較したものである。表から明らかなよう
に、従来方式では10画素に対し、読取り輝度信号
との誤差の総和は166となるが、本実施例によれ
ばその誤差は高々６で済む。すなわち、本実施例
によれば、輝度信号の維持の総和が図られたこと
になる。さらに、読取り輝度信号との誤差の２乗
誤差を用いて、下記第10式に示すＳ／Ｎ比を計算
すると、従来方式では22.7dBであるのに対し、
本実施例によれば25.7dBとなり、3dBの画質改善
を行うことができる。
Ｓ／Ｎ比＝101og２５６／（１／画素数）・Σ（誤差）
……(10)
The present invention relates to a method for quantizing image luminance signals, and an object of the present invention is to reduce the number of bits per pixel with almost no deterioration in image quality. According to the present invention, in a medium such as photographic film that can express halftones, image information is quantized,
When exposing based on this, the number of bits carrying exposure amount information per pixel can be reduced with almost no deterioration in image quality. In halftone photographs, the number of dots within one halftone dot can be significantly reduced, and the resolution can be increased while maintaining tone characteristics. 2. Description of the Related Art Conventionally, when expressing a halftone image using a medium capable of expressing binary luminance, a method similar to a dither method and a halftone photographic method have been known. In the Taser method, it is known that the brightness of a pixel is expressed by one bit per pixel, and the brightness error is allocated to two or more pixels in the vicinity of that pixel. However, in the conventional dither method, texture noise is noticeable, while in the halftone photography method, the resolution is not sufficient. In order to obtain sufficient image quality when scanning and reading an image containing halftones, quantizing the obtained luminance signal, and storing and reproducing it with a storage device, or when transmitting image information digitally, it is necessary to 8 bits (256 gradations) to 6 bits (64 gradations) are required per pixel. The number of bits per pixel required to obtain this sufficient image quality is assumed to be m bits. According to the present invention, the contour and main gradation are expressed by n bits (n<m) in the pixel, and the gradation of a slight residual value is expressed by the peripheral pixels, especially the pixel to be processed next after the pixel. to share. As a result, visual image quality hardly deteriorates even if the number of bits allocated per pixel is reduced to n=2 to 4. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a system using the present invention. 1 is a scanning reading device, and the analog luminance signal of the image read by this device is transferred to a quantizing device 2.
Quantize with . Reference numeral 3 denotes a storage device such as a magnetic disk, in which the image signal quantized by the quantizer 2 is stored and read out as necessary. 4 is a digital-to-analog conversion device that converts the read quantized image signal into an analog signal, and prints it in a recording device 5;
Restore the original painting. Note that the storage device 3 can also be replaced with a facsimile transmission line. In this case, the scanning reading device 1 and the quantizing device 2 are a transmitting terminal,
The digital-to-analog converter 4 and the recording device 5 serve as receiving terminals. Furthermore, the digital-to-analog conversion device 4 may be considered as a device for generating halftone signals, rather than a conversion device for applying digital signals to photographic paper as luminance information. FIG. 2 is a detailed block diagram of the quantizer 2 shown in FIG. 1. The m-bit quantizer 21, which performs quantization into m bits, receives the analog read luminance signal through the signal line 21A and quantizes it into an m-bit digital read luminance signal. Note that this block, that is, the m-bit quantization device 21, performs edge enhancement, gradation correction, etc., if necessary. Next, m
The digital read luminance signal of bits is sent via line 21A to an n-bit quantizer 22, which produces an n-bit luminance signal for the pixel as shown in FIG. In FIG. 3, squares indicate pixels, and arrows 31 indicate the main scanning direction of the reading device 1 shown in FIG.
Arrow 32 indicates the sub-scanning direction. Also marked pixel 3
4 is the pixel currently being processed, pixel 33 is 1 of pixel 34
The most recently processed pixel, pixel 35, is 1 of pixel 34.
This is the next pixel to be processed. Now, as shown in FIG.
If the residual luminance signal (m−n bits) of pixel 34 is h33, the read luminance signal b34 of m bits of pixel 34 is
The residual brightness signal h33 of the pixel 33 read out from the residual brightness signal device 23 via the line 23A is added to the total brightness signal t34. Then, the value of the m-bit total brightness signal t34 to the upper n bits is set as the final brightness signal B34 of the pixel 34. On the other hand, the total luminance signal t3
The residual luminance signal h34 of the lower (m−n) bit pixel 34 of
A is sent to the residual luminance signal device 23 for storage. Note that this residual luminance signal h34 is applied to the next pixel 3.
It is used as a residual luminance signal when processing 5. Now, as a method for generating the final n-bit luminance signal of the pixel 34 from the m-bit total luminance signal t34, (A) As described above, the m-bit total luminance signal t34 is generated.
pixel 34 using n bits from the top of pixel 34.
as the final luminance signal B34, and the remaining (m-
n) bits, that is, the lower (m−n) bits of the total luminance signal t34, are used to select the next pixel 3.
(B) After processing the above (A), the residual luminance signal h34 is
In some cases, +1 is added to the LSB (least significant bit) of the 4 n-bit final luminance signal B34. If +1 is added, this +1 becomes an error, so it is necessary to reflect it in the residual luminance signal h34. Therefore, from the total brightness signal t34 to the final brightness signal h
Since the residual luminance signal h34 is obtained by subtracting 34, this residual luminance signal h34 has a negative value. Specific examples of (A) and (B) above will be described below. In the case of (A), the number of bits of the read luminance signal and total luminance signal is 8, that is, m = 8, and the number of bits of the residual luminance signal is 5, that is, m - n = 5, so that the number of bits of the final luminance signal is 3. That is, let n = 3, the value of the read luminance signal to be processed now is 179 (however, the range of the luminance signal is 0 to 255), and the value of the residual luminance signal processed immediately before is 25 (however, Assuming that the range of the brightness signal is also 0 to 255), the output of the m-bit quantizer 21 and the storage state of the residual brightness signal storage device 23 are both expressed in binary numbers, so the read brightness signal b34= 10110011 ...(1) Residual brightness signal h33 = 00010101 ...(2) The total brightness signal t34 is expressed as: Total brightness signal t34 = Read brightness signal b34 + Residual brightness signal h33 ...(3) , From the above first and second equations, the third equation is: Total brightness signal t34 = 10110011 +00010101 = 11001000 ... (4) Furthermore, since the final brightness signal B34 uses up to the upper 3 bits of the total brightness signal t34, the above From the fourth equation, the final brightness signal B34 = 110... (5) Also, the residual brightness signal h34 used when processing the next pixel 35 consists of (8-3) bits from the lowest, that is, up to 5 bits. In order to use this, the residual luminance signal h34=00001000 (6) is obtained from the above-mentioned formula 4. In the case of (B), after performing the processing in (A) above, the corresponding pixel 34
+1 to the LSB of the n-bit final luminance signal B34
In order to do this, the final brightness signal B34 = 110 + 001 = 111 ... (7) is obtained from the above formula 5, and the residual brightness signal h34 is: Residual brightness signal h34 = total brightness signal t34 - final brightness signal B34 ... (8 ), and from the above equations 4 and 8, the residual luminance signal h34=11010000 −11100000=−00010000 (9). The final luminance signal of n bits per pixel generated in the above manner is sent via line 22B to the storage device 3 shown in FIG. 1, where it is stored. Next, the effect when a halftone image is processed by the above (A) will be specifically shown. The table below shows two cases in which 3-bit quantization is performed on a linearly changing 10-pixel signal as is, and one in which the residual luminance signal is converted to the next pixel using method (A) above in one embodiment of the present invention. This is a comparison of the error with the case where it is reflected. As is clear from the table, in the conventional method, the total error from the read luminance signal for 10 pixels is 166, but according to this embodiment, the error is only 6 at most. In other words, according to this embodiment, the sum total of the maintenance of the luminance signal is achieved. Furthermore, when calculating the S/N ratio shown in Equation 10 below using the square error of the error with the read luminance signal, it is 22.7 dB in the conventional method, whereas
According to this embodiment, it is 25.7 dB, making it possible to improve the image quality by 3 dB. S/N ratio = 101og256/(1/number of pixels)・Σ(error)
……(Ten)
【表】
なお、以上の説明では８ビツトの読取り輝度信
号に対し、最終的輝度信号として３ビツトのもの
を求めたが、非常に繊細な中間調再現が必要なも
のは最終的輝度信号として４〜５ビツトの量子
化、フルカラーのものでは５ビツト程度の量子化
が望ましい。
また、一走査線の最初の画素に対しては、残余
輝度信号が存在しないため、当該画素の処理に対
しては仮想の残余輝度信号を与えるようにすれば
よい。
以上説明した本発明の実施例によれば、画素あ
たりｎビツトに量子化された画像の輝度信号は、
以下のごとき特徴を有する。
(1) 画像の輝度信号を画素当りｎビツトで量子化
したにも拘らず、ｍビツトに近い階調特性を有
する。輪郭、主要階調のための情報は、当該画
素の中に表現されており、残余輝度信号のみを
隣の画素に加算する。残余輝度信号は大面積の
調子表現に必要な情報であり、１画素ずらして
も、視覚的画質劣化は少ない。
(2) 画素当りｍビツトの情報がｎビツトとなつた
ため、記憶のためのメモリー容量がｎ／ｍでよ
い。画像は情報量が大きいので、これの効果は
大きい。
(3) 残余輝度信号を、次の処理画素にのみ加えて
もよいため、装置構成が非常に簡単である。
(4) 残余輝度信号を、次の処理画素にのみ加えて
も、デイザ法にみる如く、１画素１ビツト表現
法にみる如き織目状雑音が殆んど生じない。こ
れは、残余輝度信号量が、１画素１ビツトの場
合に比し、１／２n-1に軽減されているためで
ある。
１画素１ビツトの場合には、この織目状雑音
を軽減する目的で１主走査後の画素にも残余輝
度配分を行うため、装置構成が著しく複雑とな
る。
(5) 第１図のデジタル・アナログ変換装置４をデ
ジタル信号→網点信号変換装置として、ｎビツ
トの信号より網点信号を作ると、網点信号を作
るドツトの形状を一定とした場合、網点面積は
２(n-m)となる。ｍ＝８、ｎ＝３とすると１網
点面積は1/32、従つて１次元解像力に直して
5.7倍の特性向上が計られる。なお残余輝度信
号をアナログ信号とし、読取り輝度信号に加算
し、これをｎビツト量子化と、当該画素のアナ
ログ残余輝度信号を作る方法に適用することも
当発明の範囲内である。
以上詳述した如く、本発明は、画像の輝度信号
を２ビツト以上で量子化するに際し、当該画素の
読取り輝度信号に前に処理された画素の残余輝度
信号（正又は負）を加算して行い、当該画素で発
生した残余輝度信号を、後に処理される画素に加
算して行うことを特徴とする画像輝度信号の量子
化方法であり、１画素当りのビツト数を画質劣化
を殆んど伴わずに減少させることができる。[Table] Note that in the above explanation, a 3-bit final luminance signal was obtained for an 8-bit read luminance signal, but in cases where extremely delicate halftone reproduction is required, a 4-bit final luminance signal is required. ~5-bit quantization is desirable, and for full-color images, quantization of about 5 bits is desirable. Furthermore, since there is no residual luminance signal for the first pixel of one scanning line, a virtual residual luminance signal may be given to the processing of that pixel. According to the embodiment of the present invention described above, the luminance signal of an image quantized to n bits per pixel is
It has the following characteristics. (1) Although the image luminance signal is quantized with n bits per pixel, it has gradation characteristics close to m bits. Information for the contour and main gradation is expressed in the pixel, and only the residual luminance signal is added to the neighboring pixel. The residual luminance signal is information necessary for expressing tone in a large area, and even if it is shifted by one pixel, there is little visual deterioration in image quality. (2) Since m-bit information per pixel has become n-bit information, the memory capacity for storage only needs to be n/m. Since images have a large amount of information, this effect is great. (3) Since the residual luminance signal may be added only to the next pixel to be processed, the device configuration is very simple. (4) Even if the residual luminance signal is added only to the next pixel to be processed, almost no texture noise as seen in the dither method or the one-bit-per-pixel representation method is generated. This is because the amount of residual luminance signal is reduced to 1/2 n-1 compared to the case of 1 bit per pixel. In the case of one bit per pixel, residual brightness is distributed even to pixels after one main scan in order to reduce this textured noise, which makes the device configuration extremely complicated. (5) When the digital-to-analog converter 4 in FIG. 1 is used as a digital signal → halftone signal converter and a halftone signal is created from an n-bit signal, if the shape of the dots forming the halftone signal is constant, The halftone dot area is 2 (nm) . If m = 8 and n = 3, the area of 1 halftone dot is 1/32, which is converted into one-dimensional resolution.
Characteristics are improved by 5.7 times. Note that it is also within the scope of the present invention to apply the residual luminance signal as an analog signal, add it to the read luminance signal, perform n-bit quantization, and create an analog residual luminance signal for the pixel. As detailed above, the present invention adds the residual luminance signal (positive or negative) of the previously processed pixel to the read luminance signal of the pixel when quantizing the luminance signal of an image using two or more bits. This is a method of quantizing image luminance signals, in which the residual luminance signal generated at the pixel is added to the pixel to be processed later. can be reduced without any
第１図は、本発明の方法を実施するシステムの
ブロツク図、第２図は量子化装置のブロツク構成
図、第３図は、画素配列説明図である。
１……読取装置、２……量子化装置、３……記
憶装置、４……Ｄ／Ａ変換装置、５……記録装
置、２１……ｍビツト量子化装置、２２……ｎビ
ツト量子化装置、２３……残余輝度信号記憶装
置。
FIG. 1 is a block diagram of a system implementing the method of the present invention, FIG. 2 is a block diagram of a quantization device, and FIG. 3 is an explanatory diagram of a pixel arrangement. 1...Reading device, 2...Quantization device, 3...Storage device, 4...D/A conversion device, 5...Recording device, 21...m-bit quantization device, 22...n-bit quantization Device, 23...Residual luminance signal storage device.
Claims (1)
で量子化することにより当該画素の画像輝度信号
の量子化を行う際、直前に処理された画素（ｘ−
１番目）のｍ−ｎビツト（但し、ｍ≧３、ｎ≧
２、ｍ＞ｎで、ｍ、ｎ及びｘは正の整数）より成
る残余輝度信号を記憶手段より呼出し、その残余
輝度信号を前記読取り輝度信号に加算手段により
加算して総和輝度信号とし、その総和輝度信号の
上位ｎビツトを当該画素（ｘ番目）の画像輝度信
号として量子化するとともに、その総和輝度信号
の下位ｍ−ｎビツトを次に処理する画素（ｘ＋１
番目）の残余輝度信号として前記記憶手段に記憶
させる画像輝度信号の量子化方法。1 When performing quantization of the image luminance signal of the pixel by quantizing the luminance signal of the read pixel (x-th) with n bits, the pixel processed immediately before (x-
m-n bits (however, m≧3, n≧
2. Retrieve the residual luminance signal from the storage means (m>n, m, n, and x are positive integers), add the residual luminance signal to the read luminance signal by the addition means to obtain a total luminance signal, and The upper n bits of the total luminance signal are quantized as the image luminance signal of the pixel (xth), and the lower m-n bits of the total luminance signal are quantized as the image luminance signal of the pixel (x+1) to be processed next.
A method for quantizing an image luminance signal to be stored in the storage means as a residual luminance signal of th).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56195940A JPS5896459A (en) | 1981-12-04 | 1981-12-04 | Quantizing method for picture luminance signal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56195940A JPS5896459A (en) | 1981-12-04 | 1981-12-04 | Quantizing method for picture luminance signal |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5896459A JPS5896459A (en) | 1983-06-08 |
| JPS6253107B2 true JPS6253107B2 (en) | 1987-11-09 |
Family
ID=16349495
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56195940A Granted JPS5896459A (en) | 1981-12-04 | 1981-12-04 | Quantizing method for picture luminance signal |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5896459A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0428721Y2 (en) * | 1986-06-13 | 1992-07-13 |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6074772A (en) * | 1983-09-29 | 1985-04-27 | Matsushita Electric Ind Co Ltd | Quantizing method of multi-value picture information |
| JPS6139778A (en) * | 1984-07-31 | 1986-02-25 | Seiko Epson Corp | Image binary-coding processing method |
| US4638373A (en) * | 1985-03-06 | 1987-01-20 | Metromedia, Inc. | Method and apparatus for improving gray scale resolution in an ink jet printing system |
| JPH06103922B2 (en) * | 1987-07-24 | 1994-12-14 | 松下電器産業株式会社 | Image signal processor |
| JPH01264076A (en) * | 1988-04-14 | 1989-10-20 | Dainippon Screen Mfg Co Ltd | Split exposure dot picture recorder |
| JPH02153676A (en) * | 1988-12-05 | 1990-06-13 | Pfu Ltd | Halftone processing circuit |
| JPH03139964A (en) * | 1989-10-25 | 1991-06-14 | Nec Corp | Image signal circuit for facsimile equipment |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3560957A (en) * | 1966-01-26 | 1971-02-02 | Hitachi Ltd | Signal conversion systems with storage and correction of quantization error |
| JPS56101276A (en) * | 1980-01-17 | 1981-08-13 | Fuji Photo Film Co Ltd | Signal processing system for contrast picture |
-
1981
- 1981-12-04 JP JP56195940A patent/JPS5896459A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3560957A (en) * | 1966-01-26 | 1971-02-02 | Hitachi Ltd | Signal conversion systems with storage and correction of quantization error |
| JPS56101276A (en) * | 1980-01-17 | 1981-08-13 | Fuji Photo Film Co Ltd | Signal processing system for contrast picture |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0428721Y2 (en) * | 1986-06-13 | 1992-07-13 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5896459A (en) | 1983-06-08 |
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