WO2019137396A1

WO2019137396A1 - Image processing method and device

Info

Publication number: WO2019137396A1
Application number: PCT/CN2019/070980
Authority: WO
Inventors: 林威丞
Original assignee: 华为技术有限公司
Priority date: 2018-01-12
Filing date: 2019-01-09
Publication date: 2019-07-18
Also published as: CN110033412A; CN110033412B

Abstract

Provided are an image processing method and device. The method comprises: dividing a target image into at least two blocks; determining at least one block group from the at least two blocks, wherein the materials of objects presented in various blocks in each block group of the at least one block group are the same; using at least two compensation tables to respectively perform pre-compensation on the at least one block group to obtain a color difference value corresponding to each compensation table, and determining a compensation table with the minimum color difference value to be a target compensation table; and performing color compensation on the target image according to the target compensation table. By means of the present application, a target compensation table corresponding to a light source color temperature in a photographing environment can be selected more accurately so as to accurately correct an image having a color shading phenomenon.

Description

Image processing method and device

The present application claims priority to Chinese Patent Application No. 20181003162, filed on Jan. 12, 2018, the entire disclosure of which is incorporated herein by reference. .

Technical field

The present application relates to the field of image processing technologies, and in particular, to an image processing method and an image processing apparatus.

Background technique

Color shading is a phenomenon in which an image is displayed when a photograph is taken, such as a cell phone or a camera. The image is reddish in the center of the image and greenish around. The color shading phenomenon is caused by the physical properties of an IR cut filter attached to the photosensitive member. The IR cut filter reduces the transmittance of red light with a longer wavelength due to the increase of the incident angle. The incident angle of the red light in the center of the image is smaller, the incident angle of the red light around the image is larger, and the red light entering the central region of the image More than the red light entering the image, so the center of the image is reddish and the area is green.

Since the red light intensity of the light source of different color temperature is different, the light source of different color temperature in the photographing environment determines the degree of color shading, so the auto white balance (AWB) algorithm can be used to calculate the color temperature of the light source in the photographing environment, and then the current color is utilized. The color shading compensation table corresponding to the color temperature of the light source compensates the RBG value of the preview image, thereby adjusting the color shading phenomenon of the preview image to prevent the phenomenon from occurring in the photograph taken. The specific process of calculating the color temperature of the light source in the photographing environment by using the AWB algorithm is to first determine the color information of each pixel in the preview image, the color information includes the R/G value and the B/G value of the pixel, and then use each of the preview images. The color information of the pixel calculates the color temperature of the light source in the photographing environment.

However, since the AWB algorithm is the color temperature of the light source determined by the color information of the image, the original color of the object in the image causes a misjudgment of the color temperature of the light source. For example, the color of the light source with high color temperature is light blue in the image. If there is a light blue object in the image, it is easy to misjudge the current color temperature of the light source as a high color temperature, which may result in the inability to accurately select the compensation table. Adjust the color shading phenomenon of the image.

Summary of the invention

The present application provides an image processing method and apparatus for solving the problem that the existing image processing method cannot accurately select the color shading compensation table, and thus cannot accurately adjust the color shading phenomenon of the image.

In a first aspect, the present application provides an image processing method, the method comprising the steps of: dividing a target image into at least two blocks; determining at least one block group from the at least two blocks, the at least The materials displayed by each block in each block group of one block group are the same; the at least one block group is pre-compensated by using at least two compensation tables to obtain the color difference corresponding to each compensation table. a value, the compensation table that minimizes the color difference value is determined as a target compensation table; and the target image is color-compensated according to the target compensation table.

The present invention pre-compensates the block group with the same object material in the image by using each compensation table, and obtains the color difference value corresponding to each compensation table, so that the target compensation table corresponding to the color temperature of the light source in the photographing environment can be accurately selected, Used to accurately correct images with color shading.

In conjunction with the first aspect, in a first implementation of the first aspect, the determining the at least one block group from the at least two blocks comprises: determining a location point of each block in a three-dimensional image coordinate system The coordinate values of the position points are respectively a first R/G value, a first B/G value, and a brightness value of each block; at least two reference points are determined in the three-dimensional image coordinate system, and each Position points of the blocks are classified into a group to which one of the at least two reference points belongs to obtain at least two first position point groups, and each of the at least two reference points is the each a center of gravity of all the location points in the first location point group to which the reference point belongs; determining a target group in the at least one first location point group, where the center of gravity of each of the first location point groups is located at each of the first location points Within the target group in the group, each of the target points in the target group is separated from the first location point group to which the target group belongs to a distance threshold; the distance corresponding to each target group is determined. Block group, each block corresponding to each target group Each group comprising at least one target point corresponding to the position of the block.

In conjunction with the first implementation of the first aspect, in a second implementation manner of the first aspect, the location point of each block is classified into a group to which one of the at least two reference points belongs Obtaining at least two first location point groups includes: classifying a location point of each tile into a group to which a reference point closest to a location point of each block belongs to obtain at least two second location points Determining each of the second location points if a center of gravity of each of the at least two second location point groups coincides with a reference point in each of the second location point groups The group is a first location point group; if the center of gravity of any of the at least two second location point groups does not coincide with the reference point in any of the second location point groups, The center of gravity of each second location point group is used as a new reference point, and each of the location points is grouped by the new reference point to obtain the first location point group.

In conjunction with the first implementation of the first aspect, in a third implementation manner of the first aspect, the determining the target group in the at least one first location point group includes: in the three-dimensional image coordinate system, a center of gravity of each of the at least two first location point groups is a spherical target group; if the radius of each target group in the target group is a first radius threshold, If the number of location points in each target group is not less than a quantity threshold, the radius of each target group is set as the first radius threshold; if the radius of each target group in the target group is the first a radius threshold, the number of location points in each target group is less than the number threshold, and the radius of each target group is increased until the number of location points in each target group is not Less than the number threshold, the increased radius is not greater than the second radius threshold.

In conjunction with the third implementation of the first aspect, in a fourth implementation of the first aspect, the first radius threshold R _min = (1/5) * D, the second radius threshold R _max = D Where D is the point corresponding to the color information of the gray card image obtained under the D65 standard light source in the two-dimensional coordinate system of R/G and B/G and the color information of the gray card image obtained under the D50 standard light source the distance between.

With reference to the first aspect, any one of the first to fourth implementation manners of the first aspect, in a fifth implementation manner of the first aspect, the using at least two compensation tables respectively Performing pre-compensation of at least one block group to obtain a color difference value corresponding to each compensation table includes: pre-compensating each block in each block group by using at least two compensation tables to obtain each block group a second R/G value of the block and a second B/G value; determining an R/G difference value of each block group according to a second R/G value of each block in each block group Determining, according to the second B/G value of each block in each block group, a B/G difference value of each block group; according to the R/G difference value of each block group and a B/G difference value, the color difference value corresponding to each of the pre-compensation tables is determined, and the color difference value corresponding to each pre-compensation table is an average value of all R/G difference values of all block groups and all blocks The sum of the average values of the B/G difference values of the group.

With reference to the fifth implementation manner of the first aspect, in the sixth implementation manner of the first aspect, the expression of the R/G difference value is:

R/G_DV _j =(|C_R/G ₁ -Avg_C_R/G|+|C_R/G ₂ -Avg_C_R/G|+...+|C_R/G _P -Avg_C_R/G|)/P

Where R/G_DV _j is the R/G difference value of the j-th block group in all block groups, and C_R/G _i is the second R/G of the i-th block in the j-th block group. a value, P is the number of blocks in the j-th block group, and Avg_C_R/G is an average value of second R/G values of all blocks in the j-th block group;

The expression of the B/G difference value is:

B/G_DV _j =(|C_B/G ₁ -Avg_C_B/G|+|C_B/G ₂ -Avg_C_B/G|+...+|C_B/G _P -Avg_C_B/G|)/P

Where B/G_DV _j is the B/G difference value of the j-th block group in all block groups, and C_B/G _i is the second B/G of the i-th block in the j-th block group The value, Avg_C_B/G, is the average of the second R/G values of all the blocks in the j-th block group.

With reference to the fifth implementation manner of the first aspect, in a seventh implementation manner of the first aspect, the color difference value corresponding to each pre-compensation table is a weighted average value of R/G difference values of all block groups. The sum of the weighted average of the B/G difference values for all block groups;

The expression for the weighted average of the R/G difference values for all block groups is:

R/G_TDV=(R/G_DV ₁ *V ₁ /N ₁ +R/G_DV ₂ *V ₂ /N ₂ +...+R/G_DV _K *V _K /N _K )/K

Where R/G_TDV represents the weighted average of the R/G difference values of all block groups, and R/G_DV _j is the R/G difference value of the _jth block group in all block groups, and V _j is the said The spatial size value of the target group corresponding to the j block groups, N _j is the number of blocks in the jth block group, and K is the number of all block groups;

The expression for the weighted average of the B/G difference values for all block groups is:

B/G_TDV=(B/G_DV ₁ *V ₁ /N ₁ +B/G_DV ₂ *V ₂ /N ₂ +...+B/G_DV _K *V _K /N _K )/K

Where B/G_TDV represents the weighted average of the B/G difference values of all block groups, and B/G_DV _j is the B/G difference value of the _jth block group in all block groups.

In this implementation, it is possible to represent the color difference value corresponding to the compensation table by using the weighted average of the R/G difference values of all the block groups and the weighted average of the B/G difference values of all the block groups. Comprehensively evaluate the compensation effect of each compensation table, thereby improving the accuracy of selecting the target compensation table.

In a second aspect, the present application further provides an image processing apparatus, which may be configured in a photographing apparatus or a photographing apparatus itself, the apparatus comprising: a dividing unit, configured to divide the target image into at least two blocks; a determining unit, configured to determine at least one block group from the at least two blocks, wherein each of the block groups in the at least one block group exhibits the same material material; the second determination a unit, configured to pre-compensate the at least one block group by using at least two compensation tables to obtain a color difference value corresponding to each compensation table, and determine a compensation table with a minimum color difference value as a target compensation table; And performing color compensation on the target image according to the target compensation table.

With reference to the second aspect, in a first implementation manner of the second aspect, the first determining unit is specifically configured to: determine a location point of each block in a three-dimensional image coordinate system, where coordinate values of the location points are respectively a first R/G value, a first B/G value, and a brightness value for each block; determining at least two reference points in the three-dimensional image coordinate system, and assigning a position point of each block to the location Deriving a group to which one of the at least two reference points belongs to obtain at least two first location point groups, each of the at least two reference points being a first location point to which each reference point belongs a center of gravity of all the location points in the group; determining a target group in the at least one first location point group, the center of gravity of each of the first location point groups being located in the target group in each of the first location point groups, Each of the target points in each target group in the target group is not greater than a distance threshold from a first location point group to which each target group belongs; determining a block group corresponding to each target group, each of the targets Each block group corresponding to the group includes each of the target groups A block corresponding to at least one location point.

With reference to the first implementation of the second aspect, in a second implementation manner of the second aspect, the first determining unit is further configured to: locate a location point of each block into each of the regions The position point of the block belongs to the group to which the nearest reference point belongs to obtain at least two second location point groups; if the center of gravity of each of the at least two second location point groups is equal to each of the If the reference points in the second location point group coincide, determining that each of the second location point groups is the first location point group; if any of the at least two second location point groups is in the second location point group If the center of gravity does not coincide with the reference point in any of the second location point groups, then the center of gravity of each of the second location point groups is used as a new reference point, and each of the location points is used by the new reference point. Grouping is performed to obtain the first location point group.

With reference to the first implementation of the second aspect, in a third implementation manner of the second aspect, the first determining unit is further configured to: in the three-dimensional image coordinate system, the at least two a target group of a spherical shape centered on a center of gravity of each of the first location point groups in a location point group; and if each of the target group groups has a radius of the first radius threshold, the target group is If the number of the location points is not less than the quantity threshold, the radius of each target group is set as the first radius threshold; if the radius of each target group in the target group is the first radius threshold, If the number of the location points in each target group is less than the quantity threshold, the radius of each target group is increased until the number of location points in each target group is not less than the quantity threshold. The increased radius is not greater than a second radius threshold; wherein the first radius threshold R _min = (1/5) * D, the second radius threshold R _max = D, where D is at R Gray card image obtained under D65 standard light source in /G and B/G two-dimensional coordinate system The distance between the point corresponding to the color information of gray card image obtained with the D50 standard light color point information corresponding to the next.

With reference to the second aspect, any one of the first to third implementation manners of the second aspect, in the fourth implementation manner of the first aspect, the second determining unit is specifically configured to: use at least Two compensation tables respectively pre-compensate each block in each block group to obtain a second R/G value and a second B/G value of each block in each block group; according to each of the blocks The second R/G value of each block in the block group determines an R/G difference value of each block group, and determines the second B/G value according to each block in each block group a B/G difference value of each block group; determining, according to the R/G difference value and the B/G difference value of each block group, a color difference value corresponding to each of the pre-compensation tables, wherein each The color difference values corresponding to the pre-compensation tables are the sum of the average of the R/G difference values of all the block groups and the average value of the B/G difference values of all the block groups.

With reference to the fourth implementation manner of the second aspect, in a fifth implementation manner of the second aspect, the expression of the R/G difference value is:

The expression of the B/G difference value is:

Where B/G_DV _j is the B/G difference value of the jth block group in all block groups, and C_B/G _i is the second B/G of the i th block in the j th block group The value, Avg_C_B/G, is the average of the second R/G values of all the blocks in the j-th block group.

With reference to the fourth implementation manner of the second aspect, in a sixth implementation manner of the second aspect, the color difference value corresponding to each pre-compensation table is a weighted average value of R/G difference values of all the block groups. The sum of the weighted average of the B/G difference values for all block groups;

In a third aspect, the present application also provides an image processing apparatus including a processor, a memory, and a bus system. Wherein the processor and the memory are connected by a bus system for storing instructions for executing the instructions stored by the memory to implement the image processing method of the first aspect and various implementations of the first aspect.

Since the apparatus provided by the present application can implement the image processing method of the first aspect and the various implementation manners of the first aspect, the apparatus provided by the present application has the beneficial effects and the image processing method of the first aspect. The effect is the same and will not be described here.

In a third aspect, the present application further provides a computer readable storage medium having instructions stored therein, when executed on a computer, causing a computer to execute the image processing method described in the above first aspect .

In a fourth aspect, the present application also provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the image processing method of the first aspect described above.

In a fifth aspect, the present application also provides a chip, the chip including a processor and/or program instructions, when the chip is running, implementing the image processing method of the first aspect of the present application.

DRAWINGS

FIG. 1 is a flowchart of an embodiment of an image processing method provided by the present application;

2 is an effect diagram of a block group composed of R/G values, B/G values, and luminance values similar to that provided by the present application;

FIG. 3 is a flowchart of an embodiment of a method for determining a block group according to the present application; FIG.

4 is an effect diagram of grouping position points according to the present application;

5 is a schematic diagram of distribution of standard light source points and block points in a two-dimensional coordinate system of R/G and B/G provided by the present application;

FIG. 6 is a flowchart of an embodiment of a method for determining a color difference value corresponding to a compensation table according to the present application; FIG.

FIG. 7 is a structural block diagram of an embodiment of an image processing apparatus provided by the present application; FIG.

FIG. 8 is a structural block diagram of another embodiment of an image processing apparatus provided by the present application.

Detailed ways

The image processing method provided by the present application can be applied to a photographing device, and can prevent the color shading phenomenon from occurring in the photographed image. The photographing device can be any device equipped with a camera, such as a camera, a mobile phone, a video camera or the like. The target image in the present application may be a preview image in the lens or an image after the shooting, and the present application is not specifically limited herein.

The inventive concept of the present application is to first divide a target image into a plurality of blocks, and use the R/G value, the B/G value, and the brightness value of each block to determine an area in which the same material of the image is located, and each area in the area. The R/G values of the blocks are similar, the B/G values are similar, and the luminance values are similar. Then, each block in the region is pre-compensated by using each compensation table to obtain the color difference value corresponding to the compensation table, and the color difference value is minimized. The compensation table is determined as a target compensation table for color compensation of the target image. Since the color difference value corresponding to each compensation table can reflect the effect of each compensation table on the color compensation of the target image, the target compensation table corresponding to the color temperature of the light source in the photographing environment can be accurately selected for accurate use. Fix images with color shading.

The color temperature of the light source can be divided into: D75 light source, color temperature is 7500 °K; D65 light source, color temperature is 6500 °K; D55 light source, color temperature is 5500 °K; D50 light source, color temperature is 5000 °K; CWF light source, The color temperature is 4100°K; the TL84 light source has a color temperature of 4000°K; the U30 light source has a color temperature of 3000°K; the A light source has a color temperature of 2850°K; and the H light source has a color temperature of 2300°K. The nine light sources can be called standard light sources. Among them, D75 light source, D65 light source, D55 light source and D50 light source can be classified as high color temperature light source, CWF light source, TL84 light source and U30 light source can be classified as medium color temperature light source, A light source and H light source. Can be classified as a low color temperature source.

Different red light in different color temperature sources will result in different levels of color shading, but the color of the image area where the material is the same is different because the reflection intensity of the red light is different under different light sources. The degree of difference can accurately reflect the color shading degree of the image under the color temperature of a certain light source, and then use each compensation table to pre-compensate the area where the same material in the image is located. By evaluating the compensation effect of each compensation table, the compensation effect is selected. A good compensation table can improve the accuracy of the selection target compensation table.

The R/G value of the pixel is the ratio of the red R value of the pixel to the green G value, and the B/G value is the blue B value and the green G value of the pixel, and the values of the R value, the B value, and the G value. The range can be from 0 to 255. The RGB color space can be converted into a YCbCr color space or a YUV color space, where Y can represent the brightness value of the pixel point, and the expression of the brightness value can be Y=0.299*R+0.578*G+0.114*B. It should be noted that the color information in the present application may be represented by R/G value and B/G value, or may be represented by Cb and Cr in the YCbCr color space, or by using U and V in the YUV color space. It is indicated that this application does not specifically limit the manner in which color information is represented.

It should be noted that each threshold in the present application may be determined according to the description of the present application without any creative work, and the same threshold may be different values to solve the technology to be solved by the present application. The problem is that the present application does not specifically limit the value of each threshold.

1 is a flowchart of an embodiment of an image processing method provided by the present application, and the method may specifically include the following steps.

In step 101, the target image is divided into at least two blocks.

In a specific implementation, the target image may be divided into n*m blocks, where n may represent the number of rows of the block, m may represent the number of columns of the block, and each block includes at least one pixel.

Step 102: Determine at least one block group from the at least two blocks, and each of the block groups in the at least one block group displays materials of the same material.

The R/G values of the pixels in the area where the material is the same in the image are similar, the B/G values are similar, and the brightness values are similar, so it can be determined according to the R/G value, B/G value and brightness value of each block. The area where the same object is located to get the block group. For example, in the effect diagram of the block group shown in FIG. 2, two block groups are displayed (blocks in different block groups in FIG. 2 are represented by wire frames of different gray scales), each The objects displayed in each block in the block group are the same material. Each block in the same block group may not be adjacent, and the same block may belong to different block groups.

The R/G value of each block is the ratio of the R value to the G value of the block, and the B/G value of each block is the ratio of the B value to the G value of the block. The R value of each block is the average of the R values of the pixels included in the block, and the B value of each block is the average of the B values of the pixels included in the block, and each block The luminance value is the average of the luminance values of the pixels included in the block.

As shown in FIG. 3, the specific process of determining a block group may include the following sub-steps.

Sub-step 11, determining a position point of each block in a three-dimensional image coordinate system, the coordinate values of the position points are a first R/G value, a first B/G value, and a brightness value of each block, respectively.

In order to determine the R/G value, the B/G value, and the block with the same brightness value, each area can be determined in the three-dimensional image coordinate system whose coordinate axes are the R/G value axis, the B/G value axis, and the brightness value axis, respectively. The position point of the block can be determined based on the distance between the respective position points to determine the R/G value, the B/G value, and the block whose luminance values are respectively close.

Since the values of the R/G value and the B/G value of each block are small, the value of the brightness value may be large, for example, the value range of the R/G value and the B/G value is 0-5, and the brightness value may be It is a hundred values, so the brightness value can be normalized, and the brightness value is limited to the range of R/G value and B/G value to improve the accuracy of data processing.

Sub-step 12, determining at least two reference points in the three-dimensional image coordinate system, and classifying the position points of each block into a group to which one of the at least two reference points belongs to obtain at least two a first location point group, wherein each of the at least two reference points is a center of gravity of all the location points in the first location point group to which each reference point belongs.

The number of the first location point groups may be set in advance, and may be, for example, a value of 1, 2, or 3. In order to obtain a preset number of first location point groups, the number of reference points used for grouping may be determined first, and the number of reference points is the same as the number of the first location point groups. The R/G value of the center of gravity of each first location point group is an average value of the R/G values of the location points included in the first location point group, and the B/G value of the center of gravity of each first location point group is The average value of the B/G values of the position points included in the first position point group, and the brightness value of the center of gravity of each of the first position point groups is the average value of the brightness values of the position points included in the first position point group. ,

The application can determine the first location point group by using k-means clustering algorithm, k-modes clustering algorithm, and robust clustering using links (ROCK) algorithm, wherein k-means clustering is used. The process of grouping the location points to obtain at least two first location point groups may include: randomly selecting at least two reference points in the three-dimensional image coordinate system; and locating the location of each block Entering into a group to which a reference point closest to the position point of each block belongs to obtain at least two second location point groups; if each of the at least two second location point groups is in a second position point group The center of gravity coincides with the reference point in each of the second location point groups, and then the each second location point group is determined to be the first location point group; if the at least two second location point groups are any If the center of gravity of the second location point group does not coincide with the reference point of any of the second location point groups, the center of gravity of each of the second location point groups is used as a new reference point, and the new reference is utilized. Pointing each of the location points into groups To obtain a first position of the point group.

For example, two reference points may be randomly selected in the three-dimensional image coordinate system, respectively, as the reference point a and the reference point b, and the position closer to the reference point a is classified into the second position point group A, and the distance reference is used. The position point closer to the point b is classified into the second position point group B, and then the center of gravity of the second position point group A and the center of gravity of the second position point group B are determined, if the center of gravity of the second position point group A and the reference point a If the center of gravity of the second position point group A does not coincide with the reference point b, the center of gravity of the second position point group A and the center of gravity of the second position point group B are re-grouped as a new reference point until each The center of gravity of the two-position point group coincides with the reference point of each of the second position point groups, and the two second position point groups obtained at this time are the first position point group to be determined, and the pair shown in FIG. The effect map after the grouping is performed is described as an example. G1 and G2 in FIG. 4 are the obtained two first position point groups.

It should be noted that the number of the first location point groups in the present application may also be set to one. In this case, all the location points may be classified into the first location point group, and the first location point group may be The center of gravity is the center of gravity of all the points in the target image. This application does not specifically limit the number of points in the first position.

In each of the first position point groups, the R/G values of the respective position points closer to the center of gravity of the first position point group are closer, the B/G values are closer, and the brightness values are closer, and the position points correspond to The object displayed on the block has the same probability of the same material, so the target group can be determined near the center of gravity of the first point group, and the object corresponding to the position point included in the target group has the same material. The process of determining the target group is as follows.

Sub-step 13, determining a target group in the at least one first location point group, wherein a center of gravity of each of the first location point groups is located in a target group in each of the first location point groups, each of the target groups The position centers of the plurality of location points in the target group are not greater than the distance threshold from the first location point group to which each of the target groups belongs.

When a plurality of first location point groups are obtained, one target group may be separately determined in each first location point group to obtain a plurality of target groups, or one first location point group may be selected, in the first location. A target group is determined in the point group to obtain a target group. This application does not specifically limit the number of target groups obtained.

In determining the target group, a spherical target group may be established centering on a center of gravity of each of the at least two first location point groups in the three-dimensional image coordinate system; if the target is When the radius of each target group in the group is the first radius threshold, the number of the location points in each target group is not less than the quantity threshold, and the radius of each target group is set as the first radius a threshold; if the number of location points in each target group is less than the number threshold when the radius of each target group in the target group is a first radius threshold, then each target group is increased The radius until the number of position points in each target group is not less than the number threshold, and the increased radius is not greater than the second radius threshold. If the radius of the target group increases to the second radius threshold, the number of location points in the target group is still less than the number threshold, then the target group is discarded to select the target compensation table. Position of a point within the target group is not less than the threshold number, in order to ensure regional block group is large enough to characterize color degree of shading the region, and characterization compensation effect of color shading, which threshold number N _th may be a N _th = ( n*m)/30.

The first radius threshold R _min may be R _min = (1/5) * D, and the second radius threshold R _max may be R _max = D, where D is two in R / G and B / G The distance between the point corresponding to the color information of the gray card image obtained under the D65 standard light source in the dimensional coordinate system and the point corresponding to the color information of the gray card image obtained under the D50 standard light source. Each gray card image is an image obtained by photographing a gray card having no color under each standard light source. The color information of each gray card image includes an R/G value and a B/G value, and the R value, the B value, and the G value used to calculate the R/G value and the B/G value may be respectively for each gray card image. The average value of the R values of the included pixel points, the average value of the B values, and the average value of the G values.

Taking the schematic diagram shown in FIG. 4 as an example, the two spheres shown by C1 and C2 in FIG. 4 represent the two target groups obtained. As shown in FIG. 4, the position points in each target group are concentrated, the distance between each position point is short, and the R/G value, B/G value, and brightness value of each position point are relatively similar, so each target group is The blocks corresponding to the location points within can form a corresponding block group.

When the shape of the target group is spherical, the distance threshold may be a second radius threshold. It should be noted that the shape of the target group may be a square, a rectangle, a cylinder, or the like, and the shape of the target group is not specifically limited herein.

Sub-step 14, the block group corresponding to each target group is determined, and each block group corresponding to each target group includes a block corresponding to at least one position point in each target group.

In a specific implementation, in order to ensure that the area of the block group is large enough to characterize the color shading degree of the area and to represent the compensation effect on the color shading, the block corresponding to all the position points in each target group may be used to form the block. group.

The target image may include blocks with a strong color (dark color), so a block with a stronger color may be composed of blocks with stronger color, and a block with a stronger color may affect the compensation effect. The determination, in turn, affects the selection of the target compensation table, so in sub-step 11, the position of each block in the three-dimensional image coordinate system is determined, and the coordinate values of the position points are the first R/ of each block respectively. Before the G value, the first B/G value, and the luminance value, the block that is used to form the block group to be closer to white, that is, the effective block, may be determined. The specific steps of determining the effective block may include: determining a standard light source point of each standard light source and a block point of each block in a two-dimensional coordinate system of R/G and B/G; determining each block point distance from each standard The distance of the light source point; determining the effective block, the distance of the block point of the effective block from the at least one standard light source point is not greater than the preset distance value.

The process of determining the standard light source point of each standard light source may be: first calculating the average value of the R value of the pixel points included in the gray card image obtained under each standard light source, the average value of the G value, and the average value of the B value. The R/G value of each standard light source point is the ratio of the average value of the R value to the average value of the G value, and the B/G value of each standard light source point is the average of the B value and the average value of the G value. The ratio is then determined in the two-dimensional coordinate system of R/G and B/G to determine the position of each standard source point.

FIG. 5 is a schematic diagram of the distribution of standard light source points and block points in a two-dimensional coordinate system of R/G and B/G provided by the present application. The larger dots in Figure 5 represent nine standard source points, and the smaller points represent individual block points. The distance between the block points in the dotted line range and the at least one standard light source point is not greater than the preset distance value, so the block group can be determined from the block corresponding to the block point within the dotted line range, that is, the effective block. The process of determining the block group from the effective block is similar to the process described in the above sub-step 11 to sub-step 14, and details are not described herein again.

Step 103: Perform pre-compensation on the at least one block group by using at least two compensation tables to obtain a color difference value corresponding to each compensation table, and determine a compensation table with a minimum color difference value as the target compensation table.

In the present application, a corresponding compensation table may be set in advance for the light sources of different color temperatures. When the target compensation table is selected, each compensation table may be pre-compensated, and then the color difference degree of the pre-compensated image is used to evaluate each The compensation effect of the compensation table is obtained, so that the compensation effect is better, that is, the compensation table with a lower degree of color difference of the pre-compensated image is determined as the target compensation table for adjusting the image with color shading phenomenon.

The specific process of setting the compensation table in advance may be: firstly, the gray card image under the preset color temperature of the light source is divided into a plurality of blocks, and the method of dividing the gray card image into the block is the same as the method of dividing the block into the target image. The gray card image is divided into n*m blocks, and each block in the gray card image can correspond to each block in the target image; calculating the R value and the B value of each block in the gray card image and The value of G, the R value of each block in the gray card image may be an average value of the R values of the pixels included in the block, and the G value of each block may be the G of the pixel included in the block. The average value of the value, the B value of each block may be the average value of the B values of the pixel points included in the block; the red color of each block is determined according to the R value, the G value and the B value of each block Channel gain (R-gain), green channel gain (G-gain), and blue channel gain (B-gain) to obtain a compensation table, the information in the compensation table including each block in the gray card image R-gain, G-gain, and B-gain. When G-gain is 1, R-gain is the ratio of the G value of the block to the R value, and B-gain is the ratio of the G value of the block to the B value. After determining the compensation table, in a specific pre-compensation process, the R compensation value of each pixel in the target image may be calculated by using R-gain of a plurality of corresponding blocks, and the red R value of the pixel point is multiplied by The R compensation value gives the R value of the pre-compensated pixel. The process of obtaining the G value and the B value of the pre-compensated pixel is similar to the process of obtaining the R value of the pre-compensated pixel, and will not be described herein.

As shown in FIG. 6, the process of separately compensating the at least one block group using at least two compensation tables to obtain a color difference value corresponding to each compensation table may include the following sub-steps.

Sub-step 21, pre-compensating each block in each block group with at least two compensation tables to obtain a second R/G value and a second B/G value of each block in each block group.

The second R/G value may be a ratio of the R value of the pre-compensated block to the G value, and the second B/G value may be a ratio of the B value to the G value of the pre-compensated block.

Sub-step 22, determining an R/G difference value of each block group according to a second R/G value of each block in each block group, according to each block in each block group The second B/G value determines the B/G difference value for each of the block groups.

The expression of the R/G difference value may be:

Where R/G_DV _j is the R/G difference value of the j-th block group in all block groups, and C_R/G _i is the second R/G of the i-th block in the j-th block group. The value, P is the number of blocks in the j-th block group, and Avg_C_R/G is the average value of the second R/G values of all the blocks in the j-th block group.

The expression of the B/G difference value may be:

Sub-step 23, determining, according to the R/G difference value and the B/G difference value of each block group, a color difference value corresponding to each pre-compensation table, and a color difference corresponding to each pre-compensation table The value is the sum of the average of the R/G difference values of all block groups and the average of the B/G difference values of all block groups.

Since the number of blocks in each block group and the space size of the target group may be different, the larger the number of blocks, the larger the area of the area where the same material is located, the more representative, but the space of the target group. The larger the size, the greater the difference between the R/G value, the B/G value and the brightness value between the blocks, and the less the representative is the same material, so the color difference value corresponding to each pre-compensation table can be all areas. The weighted average of the R/G difference values of the block group and the weighted average of the B/G difference values of all block groups.

Where R/G_TDV represents the weighted average of the R/G difference values of all block groups, and R/G_DV _j is the R/G difference value of the _jth block group in all block groups, and V _j is The spatial size value of the target group corresponding to the jth block group, N _j is the number of blocks in the jth block group, and K is the number of all block groups.

The compensation table can be more comprehensively evaluated by using the weighted average of the R/G difference values of all the block groups and the weighted average of the B/G difference values of all the block groups to represent the color difference values corresponding to the compensation table. The compensation effect improves the accuracy of the selected target compensation table.

Taking any compensation table as an example, the process of determining the color difference value corresponding to the compensation table is generally described: the compensation table is used to pre-compensate the RGB values of each block of each block group in the target image to determine each The second R/G value of the block; the R/G difference value of each block group is calculated according to the expression of the R/G difference value; the weighted average of the R/G difference values of all the block groups described above The expression of the value, the weighted average of the R/G difference values of all the block groups is calculated; the B/ of all the block groups is calculated by calculating the weighted average of the R/G difference values of all the block groups. A weighted average of the G difference values; determining a color difference value corresponding to the compensation table, the color difference value corresponding to the compensation table is an average of the R/G difference values of all the block groups and a B/G difference of all the block groups The sum of the average values of the values.

Step 104: Perform color compensation on the target image according to the target compensation table.

When color compensation is performed on the target image according to the target compensation table, the R value, the B value, and the G value that need to be adjusted for each pixel in the target image may be determined according to the information in the target compensation table, and it is determined that each pixel needs to be adjusted. The process of the R value, the B value, and the G value is similar to the process of the above precompensation, and will not be described herein. Finally, the R value, the B value and the G value of each pixel in the target image are adjusted accordingly to complete the color compensation of the target image.

The smaller the color difference value corresponding to the compensation table, the better the effect of using the compensation table to color compensate the image. This application uses the compensation table to pre-compensate the same block of objects in the image. The color difference value corresponding to the compensation table can accurately select the target compensation table corresponding to the color temperature of the light source in the photographing environment, so as to accurately correct the image with color shading phenomenon.

The application can also determine the color temperature of the light source in the photographing environment according to the target compensation table, and the color temperature information of the light source can be used to adjust the position of the white point calculated by the AWB algorithm, so that the image processing according to the white point position is more accurate.

FIG. 7 is a structural block diagram of an embodiment of an image processing apparatus provided by the present application. The apparatus may be configured in a photographing device or a photographing device itself. The device may include: a dividing unit 701, and a first determining unit 702. The second determining unit 703 is a compensation unit 704.

The dividing unit 701 is configured to divide the target image into at least two blocks.

The first determining unit 702 is configured to determine, from the at least two blocks, at least one block group, and each of the block groups in the at least one block group exhibits the same material material.

The second determining unit 703 is configured to pre-compensate the at least one block group with at least two compensation tables to obtain a color difference value corresponding to each compensation table, and determine a compensation table with a minimum color difference value as a target compensation. table.

The compensation unit 704 is configured to perform color compensation on the target image according to the target compensation table.

Preferably, the first determining unit 702 is specifically configured to: determine a location point of each block in a three-dimensional image coordinate system, where the coordinate value of the location point is a first R/G value of each block, respectively a B/G value and a brightness value; determining at least two reference points in the three-dimensional image coordinate system, and classifying a position point of each block into a group to which one of the at least two reference points belongs Obtaining at least two first location point groups, each of the at least two reference points being a center of gravity of all location points in the first location point group to which each reference point belongs; in at least one first location Determining a target group in a point group, wherein a center of gravity of each of the first location point groups is located in a target group in each of the first location point groups, and each of the target groups in the target group is distance from the target point The center of gravity of the first location point group to which each target group belongs is not greater than the distance threshold; the block group corresponding to each target group is determined, and each block group corresponding to each target group includes each of the targets A block corresponding to at least one location point in the group.

Preferably, the first determining unit 702 is further configured to: classify a location point of each block into a group to which a reference point closest to the location point of each block belongs to obtain at least two second a location point group; if each of the at least two second location point groups has a center of gravity coincident with a reference point in each of the second location point groups, determining each of the second The location point group is a first location point group; if the center of gravity of any of the at least two second location point groups does not coincide with the reference point in any of the second location point groups, The center of gravity of each of the second location point groups is used as a new reference point, and each of the location points is grouped by the new reference point to obtain the first location point group.

Preferably, the first determining unit 702 is further configured to: establish, in the three-dimensional image coordinate system, a spherical target centering on a center of gravity of each of the at least two first location point groups a group; if the radius of each target group in the target group is a first radius threshold, the number of location points in each target group is not less than a quantity threshold, then the radius of each target group Set to the first radius threshold; if the radius of each target group in the target group is the first radius threshold, the number of the location points in each target group is less than the quantity threshold, then increase The radius of each target group is large until the number of position points in each target group is not less than the quantity threshold, and the increased radius is not greater than a second radius threshold; wherein the first Radius threshold R _min = (1/5) * D, the second radius threshold R _max = D, where D is the gray card obtained under the D65 standard light source in the two-dimensional coordinate system of R/G and B/G The color corresponding to the color information of the image and the color of the gray card image obtained under the D50 standard light source Information corresponding to the distance between the points.

Preferably, the second determining unit 703 is specifically configured to: pre-compensate each block in each block group by using at least two compensation tables to obtain a second R/G of each block in each block group. And a second B/G value; determining an R/G difference value of each block group according to a second R/G value of each block in each block group, according to each block The second B/G value of each block in the group determines a B/G difference value of each block group; determining the location according to the R/G difference value and the B/G difference value of each block group a color difference value corresponding to each pre-compensation table, wherein the color difference value corresponding to each pre-compensation table is an average value of R/G difference values of all block groups and a B/G difference value of all block groups. The sum of the averages.

Wherein, the expression of the R/G difference value is:

The expression of the B/G difference value is:

Preferably, the color difference value corresponding to each of the pre-compensation tables is a sum of a weighted average value of R/G difference values of all block groups and a weighted average value of B/G difference values of all block groups.

Therefore, the image processing apparatus pre-compensates the block group having the same object material in the image by using each compensation table, and obtains the color difference value corresponding to each compensation table, so that the target corresponding to the color temperature of the light source in the photographing environment can be accurately selected. A compensation table for accurately correcting images with color shading.

8 is a structural block diagram of another embodiment of an image processing apparatus provided by the present application, which includes a processor 801, a memory 802, and a bus system 803. The processor 801 and the memory 802 are connected by a bus system 803 for storing instructions for executing instructions stored by the memory 802. The memory 802 of the image processing apparatus stores the program code, and the processor 801 can call the program code stored in the memory 802 to perform the following operations: dividing the target image into at least two blocks; determining at least from the at least two blocks a block group, wherein each of the block groups in the at least one block group exhibits the same material material; and the at least one block group is pre-compensated using at least two compensation tables to obtain a color difference value corresponding to each compensation table, a compensation table that minimizes the color difference value is determined as a target compensation table; and the target image is color-compensated according to the target compensation table.

It should be understood that, in this application, the processor 801 may be a central processing unit ("CPU"), and the processor 801 may also be other general-purpose processors, digital signal processors (DSPs), dedicated Integrated circuit (ASIC), off-the-shelf programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, etc. The general purpose processor may be a microprocessor or the processor or any conventional processor or the like.

The memory 802 can include read only memory and random access memory and provides instructions and data to the processor 801. A portion of the memory 802 may also include a non-volatile random access memory. For example, the memory 802 can also store information of the device type.

The bus system 803 may include a power bus, a control bus, a status signal bus, and the like in addition to the data bus.

In the implementation process, each step of the foregoing method may be completed by an integrated logic circuit of hardware in the processor 801 or an instruction in a form of software. The steps of the method disclosed in the embodiments of the present invention may be directly implemented as a hardware processor, or may be performed by a combination of hardware and software modules in the processor. The software modules can be located in a conventional storage medium such as random access memory, flash memory, read only memory, programmable read only memory or electrically erasable programmable memory, registers, and the like. The storage medium is located in memory 802, and processor 801 reads the information in memory 802 and, in conjunction with its hardware, performs the steps of the above method. To avoid repetition, it will not be described in detail here.

The present application also provides a computer readable storage medium, wherein the computer readable storage medium can store instructions that, when executed on a computer, cause the computer to perform portions of the various embodiments of the method provided by the present invention or All steps. The readable storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

The present application also provides a computer program product comprising instructions which, when executed on a computer, cause the computer to perform some or all of the steps in the above-described embodiments of the method provided by the present invention.

The present application also provides a chip that includes a processor and/or program instructions that, when executed, implement the method of the embodiment illustrated in FIG. 1 of the present application.

Those skilled in the art will clearly understand that the techniques in this application can be implemented by means of software plus the necessary general hardware platform. Based on such understanding, the technical solutions in the present application may be embodied in the form of software products in essence or in the form of software products, which may be stored in a storage medium such as ROM/RAM, magnetic Discs, optical discs, etc., include instructions for causing a computer device (which may be a personal computer, server, or network device, etc.) to perform the methods described in various embodiments of the present invention or portions of the embodiments.

The various embodiments in the present specification are described in a progressive manner, and the same similar parts between the various embodiments may be referred to each other. For example, the description of the above device or device may refer to the corresponding method embodiment. The embodiments of the invention described above are not intended to limit the scope of the invention.

Claims

An image processing method, comprising:

Dividing the target image into at least two blocks;

Determining at least one block group from the at least two blocks, wherein each of the block groups in the at least one block group exhibits the same material material;

And using at least two compensation tables to pre-compensate the at least one block group to obtain a color difference value corresponding to each compensation table, and determine a compensation table with a minimum color difference value as a target compensation table;

The target image is color compensated according to the target compensation table.
The method according to claim 1, wherein said determining at least one block group from said at least two blocks comprises:

Determining a position point of each block in a three-dimensional image coordinate system, the coordinate values of the position points are respectively a first R/G value, a first B/G value, and a brightness value of each block;

Determining at least two reference points in the three-dimensional image coordinate system, and classifying a position point of each block into a group to which one of the at least two reference points belongs to obtain at least two first position points a group, each of the at least two reference points is a center of gravity of all position points in the first location point group to which each reference point belongs;

Determining a target group in at least one first location point group, wherein a center of gravity of each of the first location point groups is located in a target group in each of the first location point groups, wherein each target group in the target group Each of the location points is separated from the first location point group to which the target group belongs to a center of gravity that is not greater than a distance threshold;

And determining, by the block group corresponding to each target group, each block group corresponding to each target group includes a block corresponding to at least one location point in each target group.
The method according to claim 2, wherein the location point of each block is classified into a group to which one of the at least two reference points belongs to obtain at least two first location point groups include:

Locating a location point of each block into a group to which a reference point closest to a location point of each of the blocks belongs to obtain at least two second location point groups;

If the center of gravity of each of the at least two second location point groups coincides with the reference point in each of the second location point groups, determining that each of the second location point groups is First location point group;

If the center of gravity of any one of the at least two second location point groups does not coincide with the reference point of the any second location point group, then each of the second location point groups The center of gravity is used as a new reference point, and each of the position points is grouped by the new reference point to obtain the first position point group.
The method of claim 2, wherein the determining the target group in the at least one first location point group comprises:

In the three-dimensional image coordinate system, a spherical target group is established centering on a center of gravity of each of the at least two first location point groups;

If the radius of each target group in the target group is the first radius threshold, the number of the location points in each target group is not less than a quantity threshold, then the radius of each target group is set to The first radius threshold;

If the radius of each target group in the target group is the first radius threshold, the number of the location points in each target group is less than the number threshold, increasing the radius of each target group Until the number of position points in each target group is not less than the number threshold, the increased radius is not greater than the second radius threshold.
The method according to claim 4, wherein said first radius threshold R min = (1/5) * D, said second radius threshold R max = D, wherein D is at R/G and The distance between the point corresponding to the color information of the gray card image obtained under the D65 standard light source in the two-dimensional coordinate system of the B/G and the point corresponding to the color information of the gray card image obtained under the D50 standard light source.
The method according to any one of claims 1 to 5, wherein the at least one block group is pre-compensated using at least two compensation tables to obtain a color difference value corresponding to each compensation table. include:

Pre-compensating each block in each block group with at least two compensation tables to obtain a second R/G value and a second B/G value of each block in each block group;

Determining an R/G difference value of each block group according to a second R/G value of each block in each block group, according to a second B of each block in each block group a /G value determines a B/G difference value for each of the block groups;

Determining, according to the R/G difference value and the B/G difference value of each block group, a color difference value corresponding to each of the pre-compensation tables, and the color difference value corresponding to each pre-compensation table is all areas. The sum of the average of the R/G difference values of the block group and the average of the B/G difference values of all the block groups.
The method of claim 6 wherein:

The expression of the R/G difference value is:

R/G_DV j =(|C_R/G 1 -Avg_C_R/G|+|C_R/G 2 -Avg_C_R/G|+...+|C_R/G P -Avg_C_R/G|)/P

Where R/G_DV j is the R/G difference value of the j-th block group in all block groups, and C_R/G i is the second R/G of the i-th block in the j-th block group. a value, P is the number of blocks in the j-th block group, and Avg_C_R/G is an average value of second R/G values of all blocks in the j-th block group;

The expression of the B/G difference value is:

B/G_DV j =(|C_B/G 1 -Avg_C_B/G|+|C_B/G 2 -Avg_C_B/G|+...+|C_B/G P -Avg_C_B/G|)/P where B/G_DV j is The B/G difference value of the j-th block group in all block groups, C_B/G i is the second B/G value of the i-th block in the j-th block group, and Avg_C_B/G is the The average of the second R/G values of all the blocks in the jth block group.
The method according to claim 6, wherein the color difference value corresponding to each of the pre-compensation tables is a weighted average of R/G difference values of all block groups and a B/G difference of all block groups. The sum of the weighted averages of the values;

The expression for the weighted average of the R/G difference values for all block groups is:

R/G_TDV=(R/G_D V 1*V 1 /N 1 +R/G_DV 2 *V 2 /N 2 +...+R/G_DV K *V K /N K )/K

Where R/G_TDV represents the weighted average of the R/G difference values of all block groups, and R/G_DV j is the R/G difference value of the jth block group in all block groups, and V j is the said The spatial size value of the target group corresponding to the j block groups, N j is the number of blocks in the jth block group, and K is the number of all block groups;

The expression for the weighted average of the B/G difference values for all block groups is:

B/G_TDV=(B/G_DV 1 *V 1 /N 1 +B/G_DV 2 *V 2 /N 2 +...+B/G_DV K *V K /N K )/K

Where B/G_TDV represents the weighted average of the B/G difference values of all block groups, and B/G_DV j is the B/G difference value of the jth block group in all block groups.
An image processing apparatus, comprising:

a dividing unit, configured to divide the target image into at least two blocks;

a first determining unit, configured to determine at least one block group from the at least two blocks, wherein each of the block groups in the at least one block group displays materials of the same material;

a second determining unit, configured to pre-compensate the at least one block group with at least two compensation tables to obtain a color difference value corresponding to each compensation table, and determine a compensation table with a minimum color difference value as a target compensation table. ;

And a compensation unit, configured to perform color compensation on the target image according to the target compensation table.
The device according to claim 9, wherein the first determining unit is specifically configured to:

Determining a position point of each block in a three-dimensional image coordinate system, the coordinate values of the position points are respectively a first R/G value, a first B/G value, and a brightness value of each block;

Determining at least two reference points in the three-dimensional image coordinate system, and classifying a position point of each block into a group to which one of the at least two reference points belongs to obtain at least two first position points a group, each of the at least two reference points is a center of gravity of all position points in the first location point group to which each reference point belongs;

Determining a target group in at least one first location point group, wherein a center of gravity of each of the first location point groups is located in a target group in each of the first location point groups, wherein each target group in the target group Each of the location points is separated from the first location point group to which the target group belongs to a center of gravity that is not greater than a distance threshold;

And determining, by the block group corresponding to each target group, each block group corresponding to each target group includes a block corresponding to at least one location point in each target group.
The device according to claim 10, wherein the first determining unit is further configured to:

Locating a location point of each block into a group to which a reference point closest to a location point of each of the blocks belongs to obtain at least two second location point groups;

If the center of gravity of each of the at least two second location point groups coincides with the reference point in each of the second location point groups, determining that each of the second location point groups is First location point group;

If the center of gravity of any one of the at least two second location point groups does not coincide with the reference point of the any second location point group, then each of the second location point groups The center of gravity is used as a new reference point, and each of the position points is grouped by the new reference point to obtain the first position point group.
The device according to claim 10, wherein the first determining unit is further configured to:

In the three-dimensional image coordinate system, a spherical target group is established centering on a center of gravity of each of the at least two first location point groups;

If the radius of each target group in the target group is the first radius threshold, the number of the location points in each target group is not less than a quantity threshold, then the radius of each target group is set to The first radius threshold;

If the radius of each target group in the target group is the first radius threshold, the number of the location points in each target group is less than the number threshold, increasing the radius of each target group Until the number of position points in each target group is not less than the quantity threshold, the increased radius is not greater than a second radius threshold; wherein the first radius threshold R min = (1/5 *D, the second radius threshold R max = D, where D is the point corresponding to the color information of the gray card image obtained under the D65 standard light source in the two-dimensional coordinate system of R/G and B/G and D50 The distance between the points corresponding to the color information of the gray card image obtained under the standard light source.
The device according to any one of claims 9 to 12, wherein the second determining unit is specifically configured to:

Pre-compensating each block in each block group with at least two compensation tables to obtain a second R/G value and a second B/G value of each block in each block group;

Determining an R/G difference value of each block group according to a second R/G value of each block in each block group, according to a second B of each block in each block group a /G value determines a B/G difference value for each of the block groups;

Determining, according to the R/G difference value and the B/G difference value of each block group, a color difference value corresponding to each of the pre-compensation tables, and the color difference value corresponding to each pre-compensation table is all areas. The sum of the average of the R/G difference values of the block group and the average of the B/G difference values of all the block groups.
The device of claim 13 wherein:

The expression of the R/G difference value is:

R/G_DV j =(|C_R/G 1 -Avg_C_R/G|+|C_R/G 2 -Avg_C_R/G|+...+|C_R/G P -Avg_C_R/G|)/P

Where R/G_DV j is the R/G difference value of the j-th block group in all block groups, and C_R/G i is the second R/G of the i-th block in the j-th block group. a value, P is the number of blocks in the j-th block group, and Avg_C_R/G is an average value of second R/G values of all blocks in the j-th block group;

The expression of the B/G difference value is:

B/G_DV j =(|C_B/G 1 -Avg_C_B/G|+|C_B/G 2 -Avg_C_B/G|+...+|C_B/G P -Avg_C_B/G|)/P where B/G_DV j is The B/G difference value of the j-th block group in all block groups, C_B/G i is the second B/G value of the i-th block in the j-th block group, and Avg_C_B/G is the The average of the second R/G values of all the blocks in the jth block group.
The apparatus according to claim 13, wherein the color difference value corresponding to each of the pre-compensation tables is a weighted average of R/G difference values of all block groups and a B/G difference of all block groups. The sum of the weighted averages of the values;

The expression for the weighted average of the R/G difference values for all block groups is:

R/G_TDV=(R/G_DV 1 *V 1 /N 1 +R/G_DV 2 *V 2 /N 2 +...+R/G_DV K *V K /N K )/K

Where R/G_TDV represents the weighted average of the R/G difference values of all block groups, and R/G_DV j is the R/G difference value of the jth block group in all block groups, and V j is the said The spatial size value of the target group corresponding to the j block groups, N j is the number of blocks in the jth block group, and K is the number of all block groups;

The expression for the weighted average of the B/G difference values for all block groups is:

B/G_TDV=(B/G_DV 1 *V 1 /N 1 +B/G_DV 2 *V 2 /N 2 +...+B/G_DV K *V K /N K )/K

Where B/G_TDV represents the weighted average of the B/G difference values of all block groups, and B/G_DV j is the B/G difference value of the jth block group in all block groups.
An image processing apparatus, comprising:

Memory for storing programs;

a processor for reading a program in the memory and performing the image processing method according to any one of claims 1 to 8.
A computer readable storage medium, comprising instructions that, when run on a computer, cause the computer to perform the method of any one of claims 1-8.
A computer program product, characterized in that it, when run on a computer, causes the computer to perform the method of any one of claims 1 to 8.