CN201509247U - Image processing apparatus for deciding pixel value of interpolation position - Google Patents

Abstract

The utility model discloses an image processing apparatus for deciding pixel value of interpolation position which is helpful for promoting the image quality to execute frame update frequency conversion running. The image processing apparatus comprises a reference vector estimation unit for generating a first reference vector and a second reference vector to the interpolation position according with the front input frame and the back input frame; an image detection unit coupled to the reference vector estimation unit for deciding the region of the interpolation position in one of an image covering region and an image exposure region according with the first reference vector and the second reference vector; and a pixel interpolation unit coupled to the image detection unit and the reference vector estimation unit for deciding the pixel value of the interpolation position according with the front input frame, the back input frame, the first reference vector, the second reference vector and the region of the interpolation position.

Description

Image processor in order to decision interpolation position pixel value

Technical field

The utility model relates to a kind of image processing mechanism, refers to a kind of in order to determine one to be positioned at the image processor that image appears the pixel value of the interpolation position that district/image covers especially.

Background technology

At present during the motion-vector of image interpolation mechanism interpolation block in determining an interpolation image, be directly to decide its motion-vector, and produce the image of this interpolation block in view of the above with the operation result of block alignment algorithm (block matching algorithm).Please refer to Fig. 1, it is the schematic diagram that image appears district/image area of coverage and motion-vector.As shown in Figure 1, image frame F ₂, F ₃System is respectively the preceding input picture F of continuous input image ₂And back input picture F ₃, and picture F _InterBeing the interpolation image that image interpolation mechanism is produced, is between preceding input picture F ₂And back input picture F ₃Between.With the motion in one dimension is example, and A '～L ' is input picture F before the representative ₂, back input picture F ₃In background video, the direction that dotted arrow among figure system expression background video moves, solid arrow is then represented the direction that a foreground object moves, at preceding input picture F ₂The background video of middle F '～I ' is covered in by this foreground object, and imports picture F after next ₃In then be that the background video of C '～F ' is covered in by this foreground object.Because the block alignment algorithm can be at preceding input picture F ₂And back input picture F ₃In all can find figure viewed from behind image A ', B ', J ', K ', L ', so, can determine the correct target motion-vector of corresponding block, and background video A ', B ', J ', K ', L ' are presented in picture F _InterGo up (as shown in Figure 1); In addition, the block alignment algorithm also can be at preceding input picture F ₂And back input picture F ₃In find the image of foreground object, therefore, can determine the correct target motion-vector of corresponding block, and the image of foreground object is presented in picture F _InterOn.

Yet, in the decision region R _InterWith R _Inter' in the target motion-vector of interpolation block the time, region R ideally _InterWith R _Inter' in the target motion-vector of interpolation block should be that the background motion-vector is so that region R _InterWith R _Inter' in can present background video, for example, region R _InterInput picture F before should presenting ideally ₂In background video C ', D ', and region R _Inter' should present ideally and afterwards import picture F ₃In background video H ', I '.Yet, in fact, because the block alignment algorithm is at back input picture F ₃In can not find background video C ', D ' (being covered by foreground object), and at preceding input picture F ₂In can not find background video H ', I ' (originally covered) by foreground object.So the block alignment algorithm also can't determine correct motion-vector in the mode of general image comparison, cause the interpolation region R _Inter, R _Inter' the actual image distortion that is presented, when being applied to picture and adding overtones band (frame rate) conversion, traditional image interpolation mechanism will significantly reduce the quality of image output.

The utility model content

Technical problem to be solved in the utility model provides a kind of image processor in order to decision interpolation position pixel value, helps to promote the quality of image of carrying out the running of frame updating frequency inverted.

In order to solve above technical problem, the utility model provides following technical scheme:

The utility model provides a kind of image processor, is used for determining that a interpolation image image area of coverage/image appears the pixel value of an interpolation position in district, and this interpolation image system imports between the picture behind the input picture and before one.This image processor includes a reference vector estimation unit, is used for according to should precedingly importing picture and this back input picture this interpolation position being produced one first reference vector and one second reference vector; One image detecting unit is coupled to this reference vector estimation unit, is used for according to this first reference vector and this second reference vector, determine this interpolation position region system be positioned at the image area of coverage and image appear the district one of them; An and pixel interpolation unit, be coupled to this image detecting unit and this reference vector estimation unit, be used for determining the pixel value of this interpolation position according to should precedingly importing picture, this back input picture, this first reference vector, this second reference vector and this interpolation position region.

The image processor that the utility model adopts in order to decision interpolation position pixel value, at belonging to the interpolation position that the image area of coverage or image appear the district in the interpolation image, when carrying out the image interpolation, can obtain preferable image, help to promote the quality of image that the execution picture doubles the frequency inverted running.

Description of drawings

Below in conjunction with the drawings and specific embodiments the utility model is described in further detail.

Fig. 1 appears the schematic diagram of district/image area of coverage and motion-vector for image.

Fig. 2 is the assembly calcspar of a preferred embodiment of image processor of the present utility model.

Fig. 3 is an assembly calcspar of reference vector estimation unit shown in Figure 2.

Fig. 4 (a), 4 (b) are that the reference vector of first embodiment of image processor of the present utility model produces schematic diagram.

Fig. 5 is an assembly calcspar of pixel interpolation unit shown in Figure 2.

Fig. 6 is another assembly calcspar of reference vector estimation unit shown in Figure 2.

Fig. 7 is another assembly calcspar of pixel interpolation unit shown in Figure 2.

[primary clustering symbol description]

205 image interpolation module

210 storage modules

215 reference vector estimation units

220 image detecting units

225 pixel interpolation unit

2151 image difference value generation modules

2152 reference vector decision module

510 object vectors decision unit

520 targets decision unit

5101 reference position generation units

5102 foreground/background vector detection unit

2,153 first mobile estimating devices

2,154 second mobile estimating devices

710 mean pixel generation units

720 hybrid references vector pixel generation unit

730 first reference vector pixel generation units

740 second reference vector pixel generation units

750 medial filters

Embodiment

At first, be easy-to-read, below be will do not covered in last the image frame by foreground object but in next image frame by background video zone that foreground object covered, be called the image area of coverage (covered area), and will be covered by foreground object in last the image frame but the background video zone of (not covered by foreground object) in next image frame, occurs, be called image and appear district (uncovered area); For instance, background video C ', D ', E ' shown in Figure 1 is the image area of coverage, and background video G ', H ', I ' are that image appears the district; Note that above definition only in order to the operation of convenient explanation embodiment of the present utility model, is not restriction of the present utility model.

Please refer to Fig. 2, it is the image processor 200 of the utility model one preferred embodiment.Image processor 200 includes an image interpolation module 205 and a storage module 210, and image processor 200 determines when being used for carrying out the motion picture interpolation that an interpolation image is positioned at the pixel value that the image area of coverage/image appears the interpolation position in district.Wherein, storage module 210 is preceding input picture and the back input picture that is used for storing at least an interpolation image; 205 of image interpolation module are coupled to storage module 210, and comprise a reference vector estimation unit 215, an image detecting unit 220 and a pixel interpolation unit 225.Reference vector estimation unit 215 is used to determine first reference vector and second reference vector of interpolation position, and image detecting unit 220 is first reference vector and second reference vector according to interpolation position, decide the interpolation position region to be positioned at one of them that the image area of coverage/image appears the district, and pixel interpolation unit 225 is the pixel value that produces interpolation position according to preceding input picture, back input picture, first reference vector, second reference vector and interpolation position region.

Specifically, please refer to Fig. 3, be a reference vector estimation unit 215 assembly calcspars among the utility model embodiment.Reference vector estimation unit 215 is used to determine first reference vector and second reference vector of interpolation position.And the reference vector that please refer to Fig. 4 (a) and 4 (b) figure produces schematic diagram, illustrates that reference vector estimation unit 215 produces the function mode of two reference vectors at interpolation position, and wherein interpolation position system is positioned at interpolation block MB ₀₀The center.At first, image difference value generation module 2151 can use the interpolation block MB that is stored in the memory modules 210 ₀₀And the motion-vector of adjacent block, or according to block alignment algorithm (blockmatching algorithm) calculating interpolation block MB ₀₀And the motion-vector of adjacent block.Block alignment algorithm system makes absolute value error summation (the Sum of Absolute Difference of two squares; SAD) minimum, algorithm is as follows:

$\mathrm{SAD}(i,j)=\underset{k-0}{\overset{N-1}{\mathrm{\Σ}}}\underset{l=0}{\overset{N-1}{\mathrm{\Σ}}}|C(x+k,y+l)-R(x+i+k,y+j+l)|,-p\≤i,j\≤p$

Motion-vector is that (m n), makes that i=m, the SAD during j=n are minimum, wherein

(1) N represents the length of block and wide;

(2) (x+k y+l) represents in target image figure field the point in the target image block to C;

(3) (x+i+k y+j+l) represents in the reference image field, with reference to the point in the image block R;

(4) p represents search area.

Then, again with interpolation block MB ₀₀A plurality of motion-vectors of motion-vector adjacent block a plurality of with it, calculate the confusion degree of motion-vector, to calculate a numerical curve.With present embodiment, numerical curve is the formed curve of section along the motion-vector confusion degree of a certain interpolation block horizontal direction, numerical curve is the difference value of a plurality of continuous blocks of the one-dimensional space, and confusion degree is represented the variation value (motion vector variance) of motion-vector, that is numerical curve includes a plurality of numerical value of the different motion-vector degrees of variation of representative on the specific direction.For example, if interpolation block MB ₀₀A plurality of motion-vectors that adjacent block a plurality of with it (shown in Fig. 4 (a), being positioned at 5 * 5 block scope) are calculated according to the block alignment algorithm are respectively MV ₀₀With MV _-2-2～MV ₂₂Then according to waiting motion-vector can calculate a motion-vector variation value MV_VAR, its algorithm is to get etc. that the maximum horizontal component deducts the wherein absolute value of minimum level component gained in the motion-vector, add etc. that maximum vertical component deducts the wherein absolute value of minimum vertical component gained in the motion-vector, MV_VAR can utilize following equation to represent it:

MV_VAR=|MAX (MV _x)-MIN (MV _x) |+| MAX (MV _y)-MIN (MV _y) | equation (1)

MV wherein _xAnd MV _yRepresent horizontal component (x axle component) and vertical component (y axle component) respectively.Be noted that 5 * 5 block scope is not to be restriction of the present utility model, it also can utilize the block scope of N * N or N * M to do it in fact, and wherein parameter N and M all are that positive integer and N are not equal to M; In addition, the mode of calculating motion-vector variation value MV_VAR also can be used equation (2) instead or equation (3) is realized:

MV_VAR=|MAX (MV _x)-MIN (MV _x) |+| MAX (MV _y)-MIN (MV _y) |+SAD equation (2)

MV_VAR=α * | MAX (MV _x)-MIN (MV _x) |+| MAX (MV _y)-MIN (MV _y) |+β * SAD equation (3)

Wherein numerical value SAD is interpolation block MB ₀₀According to the block comparison difference that block comparison method is calculated, parameter alpha, β are weighting parameters; All can variation in order to arbitrary enforcement of calculating the numerical value of representing the motion-vector degree of variation all belongs to category of the present utility model.From the above mentioned, according to equation (1), equation (2) or equation (3) one of them, image difference value generation module 2151 calculates at different interpolation blocks one by one, so can draw the first numerical curve CV, shown in Fig. 4 (b).MB ₀₀Be the interpolation block at interpolation position place, reference vector decision module 2152 is to determine interpolation block MB ₀₀Two reference vector MV ₁, MV ₂At first, with the direction (for example horizontal direction) that background or prospect image move, reference vector decision module 2152 is spatially being prolonged interpolation block MB ₀₀Both sides a plurality of (for example both sides each six, MB ₁₀～MB ₆₀With MB _-10～MB _-60) the corresponding motion-vector variation value of block, in these corresponding motion-vector variation values, take out a maximum (VAR shown in Fig. 4 (b) for example _Max), and in these corresponding motion-vector variation values, find out maximum VAR _MaxThe block that minimum corresponded to of and arranged on left and right sides for example, can find block MB _-40With MB ₅₀, and these left and right two block MB _-40With MB ₅₀Utilize motion-vector that the block alignment algorithm calculated promptly as interpolation block MB respectively ₀₀Two reference vector MV ₁, MV ₂, in other words, interpolation block MB ₀₀Reference vector MV ₁System corresponds to the maximum VAR that is positioned at numerical curve CV _MaxThe minimum VAR in left side _Min, also claim reference vector MV ₁Be interpolation block MB ₀₀First reference vector, and its reference vector MV ₂System corresponds to the maximum VAR that is positioned at numerical curve CV _MaxThe minimum VAR on right side _Min', also claim reference vector MV ₂Be interpolation block MB ₀₀Second reference vector.And reference vector MV ₁, MV ₂One of them be to correspond to background motion-vector (background motion vector), its another then corresponding to prospect motion-vector (foreground motion vector), this is because the motion-vector variation value that belongs to around the interpolation block that the image area of coverage or image appear the district will be quite big, and the minimum motion-vector variation of and arranged on left and right sides is worth pairing image block, it can be corresponding to a prospect motion-vector or a background motion-vector, looks it and is positioned at the image area of coverage or image appears Qu Erding.Therefore, if interpolation block MB ₀₀System is positioned at one of them that the image area of coverage and image appear the district, then its reference vector MV _-1, MV ₂One of them corresponding to the background motion-vector, and its another corresponding to the prospect motion-vector; Be noted that, two reference vectors among the embodiment of the present utility model are in fact respectively a prospect vector and a background vector, two reference vectors of one block may not be to be prospect, background vector just during actual operation, and right image processor 200 of the present utility model is also applicable in this situation.By above-mentioned operation, reference vector decision module 2152 can calculate first reference vector and second reference vector of each interpolation position in the interpolation image.

Then, image detecting unit 220 is according to first reference vector of interpolation position and second reference vector, decides interpolation position region system to be positioned at one of them that the image area of coverage/image appears the district.At first because embodiment of the present utility model mainly is with the example that moves horizontally image as an illustration, therefore with motion-vector direction from left to right for just, otherwise its relative direction (from right to left) is then for bearing; Yet, this non-restriction of the present utility model, all on the two dimensional surface space with a certain specific direction for just, again with its relative direction for negative example, all meet spirit of the present utility model.Image detecting unit 220 is that the reference vector with interpolation position deducts the resulting vector difference of its another reference vector, judge that interpolation position is to fall within the image area of coverage or is to fall within image to appear the district, for instance, when interpolation position is positioned at the interpolation block, image detecting unit 220 deducts its second reference vector with first reference vector, resulting vector difference is for just, therefore judge that interpolation position system belongs to the image area of coverage, the pixel value of obtaining corresponding pixel before then pixel interpolation unit 225 corresponds to according to the object vector that is determined in the input picture is used as the pixel value of interpolation position; In addition, when interpolation position is positioned at the interpolation block, image detecting unit 220 deducts its second reference vector with first reference vector of interpolation block, resulting vector difference is for negative, therefore judge that interpolation position system belongs to image and appears the district, then pixel interpolation unit 225 corresponds to the pixel value that the pixel value of obtaining a corresponding pixel in the back input picture is used as interpolation position according to the object vector that is determined; In other words, judge that interpolation position is to fall into an image area of coverage or is to fall into an image to appear the district owing to can utilize the vector difference of two reference vectors of interpolation position, so, pixel interpolation unit 225 can utilize the result of judgement, selects a pixel value of obtaining interpolation position from preceding input picture and back input picture.

Please refer to Fig. 5, is a detailed block diagram of pixel interpolation unit 225.At first, object vector decision unit 510 is according to first reference vector and second reference vector, to obtain object vector.The image area of coverage or image appear the intersection that fauna occurs in prospect and background, this intersection is a discontinuous edge, and the motion-vector of this marginal position system prospect of following moves, so object vector decision unit 510, can be according to the motion-vector (this motion-vector system is more similar to the motion-vector of prospect) at discontinuous edge, one of them is object vector to select first reference vector and second reference vector; Or object vector decision unit 510 can comprise a reference position generation unit 5101 and a foreground/background vector detection unit 5102, based on first reference vector, second reference vector and interpolation position region, the primary importance and the second place of input picture or back input picture before corresponding to respectively, and in pairing one the 3rd reference vector of primary importance and second place centre position.So in first reference vector and second reference vector, with the motion-vector or the close person of the 3rd reference vector at discontinuous edge be the prospect vector, another then is the background vector, object vector just of the present utility model.In more detail, reference position generation unit 5101 is coupled to reference vector estimation unit 215 and image detecting unit 220, according to first reference vector and interpolation position region, calculate one first reference position, and according to second reference vector and interpolation position region, calculate one second reference position, one of them of picture imported in input picture and back before wherein first reference position and second reference position system was positioned at, and determined by the interpolation position region.And foreground/background vector detection unit 5102 is coupled to reference position generation unit 5101, and the centre position of foundation first reference position and second reference position, obtains one the 3rd reference vector.And in first reference vector and second reference vector, close person with the 3rd reference vector is the prospect vector, and another then is the background vector, object vector just of the present utility model.Meaning promptly when this interpolation position is positioned at the image area of coverage, finds this first reference position and this second reference position according to this first reference vector and this second reference vector in preceding input picture; And appear when district when this interpolation position is positioned at image, in back input picture, find this first reference position and this second reference position according to this first reference vector and this second reference vector.And foreground/background vector detection unit 5102 is coupled to this reference position generation unit 5101, according to the centre position of this primary importance and this second place, and then obtains one the 3rd reference vector.And in first reference vector and second reference vector, close person with the 3rd reference vector is the prospect vector, and another then is the background vector, object vector just of the present utility model.At last, target decision unit 520 can be according to object vector and interpolation position region, selects a pixel value of obtaining interpolation position from preceding input picture and back input picture.System belongs to the image area of coverage when interpolation position, and the pixel value of obtaining corresponding pixel before target decision unit 520 corresponds to according to the object vector that is determined in the input picture is used as the pixel value of interpolation position; Appear the district when interpolation position system belongs to image, target decision unit 520 corresponds to the pixel value that the pixel value of obtaining a corresponding pixel in the back input picture is used as interpolation position according to the object vector that is determined.

Another embodiment of the present utility model, 215 pairs one interpolation positions of reference vector estimation unit are that the center produces two reference vectors.Realize and the optimum Match of back input picture by picture by importing before moving for first system of vectors of reference.Yet the acquisition of second reference vector is to realize optimum Match with preceding input picture by being offset back input picture.At first, we are to compare by block to calculate motion-vector with the computational methods of description references vector, to produce first reference vector and second reference vector, reach corresponding respectively first block comparison error and second block comparison error.The input picture realized that the block that add up is compared sum of the deviations in the process with the optimum Match of back input picture before first block comparison error tied up to and moves; And second block comparison error ties up to by being offset back input picture and realizes that in the process with the optimum Match of preceding input picture, the block that add up is compared sum of the deviations.Preferred embodiment please refer to the 6th figure, is the assembly calcspar of reference vector estimation unit 215 in the present embodiment.Reference vector estimation unit 215 can comprise the first mobile estimating device 2153 and the second mobile estimating device 2154, is used for producing respectively first reference vector and second reference vector, and first corresponding block comparison error and second block comparison error.Then, image detecting unit 220 is compared error when first block comparison error greater than second block, and the image block that means back input picture fails to find best match in preceding input picture, and the block at interpolation position place should be positioned at image and appear the district as can be known; Relatively, compare error when second block comparison error greater than first block, import the image block of picture before meaning and fail to find best match in back input picture, interpolation position place block should be positioned at the image area of coverage as can be known.

At last, pixel interpolation unit 225 is according to judgement, first reference vector, second reference vector, preceding input picture and the back input picture of location of pixels region, produce the plural reference motion-vector, and obtain the pixel value of the interpolation position of a plurality of references according to this.At last, get mediant from the pixel value of the interpolation position of plural reference, as the pixel value of interpolation position via medial filter.In more detail, please refer to Fig. 7, is the calcspar of the specific embodiment of pixel interpolation unit 225 in the present embodiment.Wherein mean pixel generation unit 710 is that the pixel value of the preceding input picture of interpolation position and back input picture is average, produces the first candidate pixel value.Hybrid reference vector pixel generation unit 720 is after first reference vector and second reference vector are carried out a weighting, to produce a mixed vector, and according to the interpolation position region, produce at least one second candidate pixel value.The first reference vector pixel generation unit 730 is according to first reference vector and interpolation position region, produces the 3rd candidate pixel value.The second reference vector pixel generation unit 740 is according to second reference vector and interpolation position region, produces the 4th candidate pixel value.At last, medial filter 750 is by in the above-mentioned candidate pixel value, the pixel value of selecting meta is as output, for example: with pixel value 8 (0～255) is example, suppose that first pixel value is that 100, second pixel value is that the 80 and 90, the 3rd pixel value 200, the 4th pixel value are 110, then first pixel value 100 occupy figure place among the above-mentioned pixel value, medial filter 650 outputs first pixel value 100.

In sum, at belonging to the interpolation position that the image area of coverage or image appear the district in the interpolation image, image processor 200 among the embodiment of the present utility model can obtain preferable image when carrying out the image interpolation, helps to promote the quality of image of carrying out the running of frame updating frequency inverted.

The above only is preferred embodiment of the present utility model, and all equalizations of being done according to the utility model claim change and modify, and all should belong to covering scope of the present utility model.

Claims (10)

1. an image processor is used for determining that a interpolation image image area of coverage/image appears the pixel value of an interpolation position in district, and this interpolation image is imported before one between a picture and the back input picture, it is characterized in that this image processor includes:

One reference vector estimation unit is used for according to should precedingly importing picture and this back input picture this interpolation position being produced one first reference vector and one second reference vector;

One image detecting unit is coupled to this reference vector estimation unit, is used for according to this first reference vector and this second reference vector, determine this interpolation position region be positioned at the image area of coverage and image appear the district one of them; And

One pixel interpolation unit, be coupled to this image detecting unit and this reference vector estimation unit, be used for determining the pixel value of this interpolation position according to should precedingly importing picture, this back input picture, this first reference vector, this second reference vector and this interpolation position region.

2. image processor as claimed in claim 1 is characterized in that, this pixel interpolation unit is used to determine the pixel value of this interpolation position, when this interpolation position is positioned at the image area of coverage, is determined the pixel value of this interpolation position by input picture before this; Otherwise, when being positioned at image, this interpolation position appears when district, import the pixel value that picture determines this interpolation position by this back.

3. image processor as claimed in claim 1, it is characterized in that, this pixel interpolation unit, according to should precedingly importing picture, this back input picture, this first reference vector, this second reference vector and this interpolation position region, produce the plural candidate pixel value, and the selection one is the pixel value of this interpolation position from this plural candidate pixel value.

4. image processor as claimed in claim 1 is characterized in that, this reference vector estimation unit includes:

One first mobile estimating device is imported picture forward by back input picture, carries out the block comparison, determining this first reference vector, and produces one first corresponding error amount; And

One second mobile estimating device is imported picture backward by preceding input picture, carries out block comparison, determining this second reference vector, and produces one second corresponding error amount.

5. image processor as claimed in claim 4, it is characterized in that, this image detecting unit, according to this first error amount of this first reference vector correspondence and this second error amount of this second reference vector correspondence, determine this interpolation position region be positioned at the image area of coverage and image appear the district one of them.

6. image processor as claimed in claim 1, it is characterized in that this reference vector estimation unit is the plural motion-vector according to this interpolation position one side, to determine this first reference vector, reach plural motion-vector, to determine this second reference vector according to this interpolation position opposite side.

7. image processor as claimed in claim 6 is characterized in that, the pixel interpolation unit pack contains::

One object vector decision unit is coupled to this reference vector estimation unit, and one of them is the background vector to be used to determine this first reference vector and this second reference vector; And

One target decision unit is used for determining the pixel value of this interpolation position according to this background vector and this interpolation position region.

8. image processor as claimed in claim 7 is characterized in that, object vector decision unit pack contains:

One reference position generation unit, be coupled to this reference vector estimation unit and this image detecting unit, according to this first reference vector and this interpolation position region, calculate one first reference position, and according to this second reference vector and this interpolation position region, calculate one second reference position, one of them of picture imported in input picture and back before wherein this first reference position and this second reference position were positioned at, and determined by this interpolation position region; And

One foreground/background vector detection unit, be coupled to this reference position generation unit, according to the centre position of this first reference position and this second reference position, obtain one the 3rd reference vector, and determine that according to this background vector is one of them of this first motion-vector and this second motion-vector.

9. as claim 7 or 8 described image processors, it is characterized in that this target decision unit is used for being positioned at the image area of coverage when this location of pixels, according to preceding input picture and this background vector, determines the pixel value of this location of pixels.

10. as claim 7 or 8 described image processors, it is characterized in that this target decision unit is used for appearing the district when this location of pixels is positioned at image, according to back input picture and this background vector, determines the pixel value of this location of pixels.

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