CN113676712A

CN113676712A - Color correction method and related device thereof

Info

Publication number: CN113676712A
Application number: CN202110709858.5A
Authority: CN
Inventors: 邵一轶; 况璐; 潘武
Original assignee: Zhejiang Dahua Technology Co Ltd
Current assignee: Zhejiang Dahua Technology Co Ltd
Priority date: 2021-06-25
Filing date: 2021-06-25
Publication date: 2021-11-19
Anticipated expiration: 2041-06-25
Also published as: CN113676712B

Abstract

The application discloses a color correction method and a related device thereof, wherein the color correction method comprises the following steps: acquiring color information and a color temperature estimated value of equipment to be debugged; selecting corresponding color data from a color space data table of the reference equipment according to the color information and the color temperature estimation value; obtaining a target color matrix by using the color data, and obtaining a source color matrix; and calculating to obtain a color correction value according to the target color matrix and the source color matrix, and correcting the color information of the device to be debugged by using the color correction value. By the method, the debugging efficiency of the color style debugging of the equipment is effectively improved.

Description

Color correction method and related device thereof

Technical Field

The present application relates to the field of image processing technologies, and in particular, to a color correction method and a related apparatus.

Background

Video monitoring is an important component of security protection, and along with the development of security protection technology, the improvement of video image quality is more and more emphasized. The color is the most important component of the image quality, and the appearance presented by the style characteristics of the color is often the first index for the user to evaluate the video.

Fig. 1 is a graph of sensor versus RGB spectral response, and fig. 2 is a graph of human eye versus RGB spectral response. As can be seen from fig. 1 and 2, the response curves of the human eye and the sensor (camera) to the RGB spectrum are not consistent, and the image is usually color-shifted after white balance processing, so that the image needs to be corrected by a color matrix.

Currently, the most common way to do video color processing is CCM matrix. Ccm (color correction matrix) is a color correction method for correcting the difference between the spectral response of the sensor and the human eye, so that the video image is closer to the physical world seen by the human eye. The existing CCM matrix is generally used in real time in equipment by calibrating a group of target CCM matrixes respectively at high, medium and low color temperatures in advance, the equipment estimates the color temperature value of a current monitoring picture through diffusion, and then the corresponding CCM matrixes are searched for use in the equipment through interpolation. In actual use, however, the action of calibrating the CCM in advance is to achieve color style unification between the debuggee device and the target device. In the debugging process, the color style difference between the debugged equipment and the target equipment is usually subjectively judged by human eyes, each element in a 3 x 3 matrix of the CCM is finely adjusted according to the debugging experience of actual debugging personnel, the color style difference is compared at the equipment end after adjustment, and the intermediate process is time-consuming and labor-consuming and has very low efficiency.

Disclosure of Invention

The technical problem mainly solved by the present application is to provide a color correction method and a related device thereof to improve the debugging efficiency of the color style debugging of the device.

In order to solve the above technical problem, the present application provides a color correction method, including: acquiring color information and a color temperature estimated value of equipment to be debugged; selecting corresponding color data from a color space data table of the reference equipment according to the color information and the color temperature estimation value; obtaining a target color matrix by using the color data, and obtaining a source color matrix; and calculating to obtain a color correction value according to the target color matrix and the source color matrix, and correcting the color information of the device to be debugged by using the color correction value.

Before the step of selecting corresponding color data from a color space data table of the reference device according to the color information and the color temperature estimation value, the method comprises the following steps: acquiring reference color information of reference equipment under different color temperatures; and establishing a color space data table according to the reference color information.

Wherein, the step of selecting corresponding color data from the color space data table of the reference device according to the color information and the color temperature estimation value comprises: and selecting Lab data corresponding to the color temperature estimated value and the color information from the color space data table according to the color information and the color temperature estimated value.

The method for obtaining the target color matrix and the source color matrix by using the color data comprises the following steps: converting the acquired Lab data into RGB data; and carrying out the inverse operation of the sRGB standard on the RGB data to obtain a target color matrix.

Wherein the step of converting the Lab data into RGB data comprises: converting Lab data into XYZ data, and correcting the XYZ data; the corrected XYZ data is converted into RGB data.

The method comprises the following steps of obtaining a target color matrix by using color data and obtaining a source color matrix, and further comprises the following steps: acquiring an rgb three-channel value of a block where color information is located according to the color information; and acquiring a gamma value of the equipment to be debugged, and performing gamma operation on the rgb three-channel value to obtain a mapped source color matrix.

The method comprises the following steps of calculating a color correction value according to a target color matrix and a source color matrix, and correcting color information of equipment to be debugged by using the color correction value, wherein the steps comprise: performing matrix operation on the target color matrix and the source target matrix to obtain an initial color correction value; normalizing the initial color correction value to obtain a color correction value; and performing matrix operation by using the color correction value and a source RGB matrix of the equipment to be debugged to obtain corrected color information.

The method for acquiring the color information and the color temperature estimated value of the device to be debugged comprises the following steps of: and estimating the current temperature of the equipment to be debugged by an algorithm to obtain a color temperature estimated value.

The method comprises the following steps of estimating the current temperature of equipment to be debugged through an algorithm to obtain a color temperature estimated value, wherein the method comprises the following steps: pre-recording the white balance gain expression of equipment in different color temperature environments; and matching the actual white balance calculation result in the actual environment with the white balance gain expression to obtain the color temperature estimation value corresponding to the actual environment.

The present application further provides a terminal, which includes a processor and a memory coupled to each other, the memory is used for storing program instructions, and the processor is used for executing the program instructions stored in the memory to implement the color correction method of any of the above embodiments.

The present application also provides a computer-readable storage medium having a computer program stored thereon for implementing the color correction method of any of the above embodiments.

The beneficial effect of this application is: compared with the traditional inefficient method of debugging the CCM matrix by relying on human subjective evaluation, the method has the advantages that the color style of the equipment to be debugged is corrected through the color correction value, the characteristic that color space is quantitatively expressed to color is fully utilized under the condition of assistance of an intelligent detection algorithm, the Lab space which is most close to human eyes to color feeling is selected, the method that the equipment to be debugged can best approach the color style of the target equipment is found through conversion of RGB three-channel statistic values and the data conversion relation among the spaces, the color correction method does not need human intervention, is suitable for a security camera in the actual working condition, can be converted and taken effect in real time in the equipment, and the inefficient method that manual pre-calibration is avoided and subjective evaluation is relied on is avoided.

Drawings

FIG. 1 is a schematic structural diagram of an embodiment of a color correction method according to the present application;

FIG. 2 is a schematic flow chart illustrating one embodiment of creating a color space data table according to the present application;

FIG. 3 is a schematic flow chart illustrating an embodiment of obtaining a target color matrix according to the present disclosure;

FIG. 4 is a diagram of the features presented in the sRGB standard on a display space;

FIG. 5 is a schematic flow chart illustrating one embodiment of obtaining a source color matrix according to the present application;

FIG. 6 is a flowchart illustrating an embodiment of step S14 in FIG. 1;

FIG. 7 is a block diagram of an embodiment of a terminal of the present application;

FIG. 8 is a schematic structural diagram of an embodiment of a storage medium according to the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that the process of image color migration is a process of changing the image color tone, and it is usually desirable to change one color attribute of an image without changing other color attributes of the image. Three channels in the RGB space have strong correlation, while each channel in the Lab space has minimal correlation. Therefore, it becomes convenient to come out the color of the image in the Lab space. The XYZ color space is used for the purpose of mediating RGB and LAB color space conversions.

Generally, AWB corrects white and the corresponding other colors follow a significant change, so to speak, the colors are substantially correct, but the saturation is somewhat low and the colors are somewhat off-set. The CCM matrix is to keep the white (gray) unchanged and correct the other colors to a very precise level.

It should be noted that the color space refers to a method for quantitatively describing a subset of colors. The RGB, XYZ, and Lab spaces are three different color spaces that describe a subset of colors. The RGB space refers to a specific color described by three color components of red, green and blue. The XYZ space is a mathematically defined color space whose real name is the CIE 1931 XYZ color space. The Lab space (collectively CIRLAB) is a color space designed based on human perception of color, where L represents luminance, a represents a green to red component, and b represents a blue to yellow component.

Referring to fig. 1, fig. 1 is a schematic structural diagram illustrating an embodiment of a color correction method according to the present application. As shown in fig. 1, the color correction method includes:

step S11: and acquiring color information and color temperature estimated values of the equipment to be debugged.

In this embodiment, the color information of the device to be debugged is color information of an image shot by the device to be debugged in a current monitoring scene (including a current ambient temperature). The color temperature is a measurement unit which represents that the light contains color components, and the estimated value of the color temperature of the device to be debugged is the ambient temperature of the device to be debugged or the color temperature of an image shot by the device to be debugged.

The color temperature estimated value is obtained according to color information of an image shot by the device to be debugged. The method specifically comprises the following steps: color temperature estimation is performed by an algorithm. In one embodiment, white balance gain expressions of the device to be debugged in different color temperature environments are recorded in a laboratory environment in advance, matching is performed in an actual environment according to an actual white balance calculation result of the device to be debugged and the white balance gain expressions in the laboratory environment which are recorded in advance, and a color temperature estimation value in the current actual environment is obtained correspondingly. There are many algorithms for obtaining the estimated color temperature, and the algorithm is not limited herein.

Step S12: and selecting corresponding color data from a color space data table of the reference equipment according to the color information and the color temperature estimated value.

And selecting color data corresponding to the color information and the color temperature estimated value from a color space data table stored in reference equipment according to the acquired color information and the color temperature estimated value of the equipment to be debugged.

The method also comprises the following steps: reference color information of the reference equipment under different color temperatures is obtained, and a color space data table is established according to the reference color information. Referring to fig. 2, fig. 2 is a schematic flow chart illustrating an embodiment of creating a color space data table according to the present application. As shown in fig. 2, includes:

step S21: reference color information of a reference device at different color temperatures is obtained.

The color information acquired by the reference device is a standard that the color information of the device to be debugged needs to be debugged. In this embodiment, the color information acquired by the reference device is standard color information. The color style difference generated by subjective debugging of human eyes is replaced by using the color information acquired by the reference equipment as a debugging standard.

Specifically, it is preset in a laboratory environment that color information on a color chart is collected for the color chart under different color temperature environments by using a reference device. The color card is a standard color card, and can also be a custom color card.

Step S22: and establishing a color space data table according to the reference color information.

Wherein, the color space data table records a Lab space data table, and specifically establishes Lab data under different color temperatures. The Lab space data is designed based on human color perception, and has a good characteristic of being device-independent, so that the color space can clearly determine how each color is created and displayed after the white point of the color space is given, and the color space has no relation with a used display medium, so that the deviation of reference color recording caused by factors such as devices can be reduced by using the Lab space data to record the color information on the standard color card as the reference color.

Specifically, please refer to the format of the color space data table of the device varying with the color temperature as shown in table 1:

TABLE 1 reference equipment Lab Table with color temperature variation

2400k and 4800k in the table are example temperatures, and include Lab data corresponding to different colors at other temperatures in addition to the example temperatures 2400k and 4800k in the table, and include Lab data corresponding to other colors in addition to the example colors (red, yellow, blue) in the table.

The manner of acquiring the color data in step S12 includes: lab data corresponding to color information and color temperature estimates are selected from Table 1 above. Specifically, all color information in the monitoring scene of the device to be detected is acquired, and color search is performed in the two-dimensional table 1 according to the color information, for example, if the current monitoring scene includes red and blue information and the color temperature estimation value is around 2400k, red Lab (L00, a00, b00) and blue (L02, a02, b02) in table 1 are extracted.

Step S13: and obtaining a target color matrix by using the color data, and obtaining a source color matrix.

The method comprises the following steps: and obtaining a target color matrix and obtaining a source color matrix.

The target color matrix and the source color matrix are both RGB matrices, and therefore, the obtained color data needs to be converted into RGB matrices.

Specifically, fig. 3 shows a method for obtaining a target color matrix, where fig. 3 is a schematic flow chart of an embodiment of obtaining a target color matrix according to the present application, and the method includes:

step S31: converting the acquired Lab data into XYZ data, and correcting the XYZ data.

Specifically, the acquired Lab data is converted into XYZ data, which is a color data expression of an XYZ space, from the Lab data acquired in step S12.

The conversion mode of the Lab space data and the XYZ space data is as follows:

definition f_y＝(L^*+16)/116，f_x＝f_y+a^*/500，f_z＝f_y-b^*/200, wherein L^*，a^*，b^*Is a matrix of each vector of Lab spatial data.

If f is_y>Delta, then

Otherwise Y is (f)_y-16/116)3δ²Y_n；

If f is_x>Delta, then

Otherwise X is (f)_x-16/116)3δ²X_n；

If f is_z>Delta, then

Otherwise Z is (f)_z-16/116)3δ²Z_n(ii) a Wherein δ is 6/29.

After converting Lab data into XYZ data by the above formula, correction processing is also performed on the XYZ data.

Step S32: the corrected XYZ data is converted into RGB data.

The conversion mode of the XYZ space data and the RGB space data is as follows:

R＝(X×3229543-Y×1611819-Z×569148)>>20

G＝(-X×965985+Y×1967119+Z×47422)>>20

B＝(X×55460-Y×213955+Z×1207070)>>20

XYZ data is converted into RGB data by the above formula.

Wherein the RGB data is a color data representation of an RGB space.

Step S33: and carrying out the inverse operation of the sRGB standard on the RGB data to obtain a target color matrix.

Wherein, the sRGB standard is a universal color standard. Specifically, the color expression of the target device is subjected to standard sRGB conversion in display transmission, in addition to passing through the gamma module of the device itself, due to the Lab values at different color temperatures acquired based on the device. The features of the standard presented in the display space are shown in fig. 4, and fig. 4 is a feature diagram of the sRGB standard presented in the display space. Therefore, after converting Lab data into RGB space, sRGB needs to be used to perform inverse operation again, and the finally obtained RGB data is a targetRGB matrix (target color matrix) equivalent to a sourceRGB matrix (source color matrix) in the device to be debugged.

Among them, the reverse operation of the sRGB standard is similar to the reverse operation of gamma. In this embodiment, the sRGB standard may be regarded as a two-dimensional table of gamma2.2 standard, and the inverse operation is to bring the three RGB channels into the ordinate of the table to find the abscissa of the corresponding mapping relationship, thereby obtaining the targetRGB matrix.

The method for obtaining the source color matrix is further included in step S13, please further refer to fig. 5, and fig. 5 is a flowchart illustrating an embodiment of obtaining the source color matrix according to the present application. As shown in fig. 5, includes:

step S51: and acquiring the rgb three-channel value of the block where the color information is located according to the color information.

The color information is obtained through the equipment to be debugged under the current monitoring scene, and specifically refers to the color information for identifying the monitoring object in the image after the intelligent algorithm is started.

Specifically, after color information in the current monitoring scene is obtained through intelligent detection, an average value of rgb three-channel statistics corresponding to the color region is stored, for example, red is detected at the upper left corner of the image, data operation is performed on the rgb channel information of all pixel points corresponding to the red region at the upper left corner of the image, and the obtained average value is an average rgb channel value of the red region. And sequentially acquiring the rgb channel values of the blocks where the color information is located by the method.

Step S52: and acquiring a gamma value of the equipment to be debugged, and performing gamma operation on the rgb three-channel value to obtain a mapped source color matrix.

The gamma value is actually a two-dimensional lookup table, with the abscissa being the input value and the ordinate being the output value. Specifically, the rgb three-channel values are taken as input values respectively and are brought into a two-dimensional gamma table, and an rgb three-channel output value matrix under a corresponding relationship is obtained through query, wherein the rgb three-channel output value matrix is a sourceRGB matrix (source color matrix).

Step S14: and calculating to obtain a color correction value according to the target color matrix and the source color matrix, and correcting the color information of the device to be debugged by using the color correction value.

In this embodiment, the target color matrix and the source color matrix are both a matrix composed of a plurality of three-dimensional arrays, where the dimensions of the target color matrix and the source color matrix are always the same, and how many sets of data correspond to how many colors of a scene corresponding to the device. The matrix mode of the data composition is shown in the following table 2:

TABLE 2A color matrix

R1	G1	B1
			R2	G2	B2
R3	G3	B3
			R4	G4	B4
/	/	/

The expression of the target color matrix and the source color matrix can be as shown in table 2 above.

Specifically, referring to fig. 6, fig. 6 is a flowchart illustrating an embodiment of step S14 in fig. 1. As shown in fig. 6, includes:

step S61: and performing matrix operation on the target color matrix and the source target matrix to obtain an initial color correction value.

Specifically, a target color matrix/source color matrix is calculated by using matrix operation to obtain an initial color correction value. In the present embodiment, the initial color correction values are a 3 × 3 matrix.

Step S62: and carrying out normalization processing on the initial color correction value to obtain a color correction value.

Specifically, the above-described initial matrix of 3 × 3 is subjected to normalization calculation. Assume that the 3 × 3 matrix result is [ c00 c01 c 02; c10 c11 c 12; c20 c21 c22], the normalization processing mode comprises: c02 ═ 1-c00-c 01; c12 ═ 1-c10-c 11; c22 is 1-c20-c 21. In the present embodiment, normalization is performed to ensure normalization of the initial matrix. The initial color correction matrix may also be constrained in other ways in other embodiments.

Wherein the color correction value is a CCM matrix.

Step S63: and performing matrix operation by using the color correction value and a source RGB matrix of the equipment to be debugged to obtain corrected color information.

Specifically, the product of the CCM matrix and the source RGB matrix is calculated by using matrix operation to obtain a corrected color matrix. The specific calculation formula is as follows:

the beneficial effects of this embodiment: the color correction value required by the device to be debugged is obtained through the reference device, and the color style of the device to be debugged is debugged according to the obtained color correction value, so that the image color style debugging of the device to be debugged is consistent with the color style of the reference device. Compared with the traditional low efficiency of debugging by relying on manual subjective evaluation of a CCM matrix, the method has the advantages that the characteristic that color space is quantized and expressed to color is fully utilized under the condition of assistance of an intelligent detection algorithm, the Lab space which is most close to human eyes to color feeling is selected, the data conversion relation among the three channels of RGB statistics is utilized for conversion, and the method that the device to be debugged can best approach the color style of the target device is found.

Fig. 7 is a schematic structural diagram of an embodiment of a terminal according to the present application.

The terminal 70 comprises a processor 71 and a memory 72 coupled to each other, and the processor 71 is configured to execute program instructions stored in the memory 72 to implement the steps in any of the above-mentioned method embodiments or the steps correspondingly executed by the color correction method in any of the above-mentioned method embodiments. The terminal may include, in addition to the processor and the memory, a touch screen, a printing component, a communication circuit, and the like according to requirements, which are not limited herein.

Specifically, the processor 71 is configured to control itself and the memory 72 to implement the steps in any of the color correction method embodiments described above. The processor 71 may also be referred to as a CPU (Central Processing Unit). The processor 71 may be an integrated circuit chip having signal processing capabilities. The Processor 71 may also be a general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. In addition, the processor 71 may be commonly implemented by a plurality of integrated circuit chips.

Referring to fig. 8, fig. 8 is a schematic structural diagram of an embodiment of a computer-readable storage medium 80.

The computer-readable storage medium 80 comprises a computer program 801 stored thereon, which computer program 801, when executed by the processor described above, performs the steps of any of the above-described method embodiments or the steps correspondingly performed by the color correction method of the above-described method embodiments.

In particular, the integrated unit, if implemented in the form of a software functional unit and sold or used as a separate product, may be stored in a computer readable storage medium 80. Based on such understanding, the technical solution of the present application may be substantially implemented or contributed to by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium 80 and includes instructions for causing a computer device (which may be a personal computer, a server, a network device, or the like) or a processor (processor) to execute all or part of the steps of the method of the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

The above description is only an example of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings, or which are directly or indirectly applied to other related technical fields, are intended to be included within the scope of the present application.

Claims

1. A color correction method, comprising:

acquiring color information and a color temperature estimated value of equipment to be debugged;

selecting corresponding color data from a color space data table of reference equipment according to the color information and the color temperature estimated value;

obtaining a target color matrix by using the color data, and obtaining a source color matrix;

and calculating to obtain a color correction value according to the target color matrix and the source color matrix, and correcting the color information of the device to be debugged by using the color correction value.

2. The color correction method according to claim 1, wherein said step of selecting corresponding color data from a color space data table of a reference device based on said color information and said color temperature estimation value is preceded by the step of:

acquiring reference color information of the reference equipment under different color temperatures;

and establishing the color space data table according to the reference color information.

3. The color correction method according to claim 2, wherein said step of selecting corresponding color data from a color space data table of a reference device based on said color information and said color temperature estimation value comprises:

and selecting Lab data corresponding to the color temperature estimated value and the color information from the color space data table according to the color information and the color temperature estimated value.

4. The color correction method according to claim 3, wherein the step of obtaining a target color matrix and obtaining a source color matrix using the color data comprises:

converting the acquired Lab data into RGB data;

and carrying out the inverse operation of the sRGB standard on the RGB data to obtain the target color matrix.

5. The color correction method according to claim 4, wherein the step of converting the Lab data into RGB data comprises:

converting the Lab data into XYZ data, and correcting the XYZ data;

converting the corrected XYZ data into the RGB data.

6. The color correction method according to claim 1, wherein the step of obtaining a target color matrix and obtaining a source color matrix using the color data further comprises:

acquiring an rgb three-channel value of a block where the color information is located according to the color information;

and acquiring a gamma value of the device to be debugged, and performing gamma operation on the rgb three-channel value to obtain the mapped source color matrix.

7. The color correction method according to claim 1, wherein the step of calculating a color correction value according to the target color matrix and the source color matrix and correcting the color information of the device to be debugged by using the color correction value comprises:

performing matrix operation on the target color matrix and the source target matrix to obtain an initial color correction value;

normalizing the initial color correction value to obtain the color correction value;

and performing matrix operation by using the color correction value and a source RGB matrix of the device to be debugged to obtain the corrected color information.

8. The color correction method according to claim 1, wherein the step of obtaining the color information and the color temperature estimation value of the device to be debugged comprises:

and estimating the current temperature of the equipment to be debugged through an algorithm to obtain the color temperature estimated value.

9. The color correction method according to claim 8, wherein the step of estimating the current temperature of the device to be debugged by the algorithm to obtain the estimated color temperature value comprises:

pre-recording the white balance gain expression of equipment in different color temperature environments;

and matching an actual white balance calculation result in an actual environment with the white balance gain expression to obtain the color temperature estimation value corresponding to the actual environment.

10. A terminal, comprising a processor and a memory coupled to each other, wherein the memory is configured to store program instructions, and the processor is configured to execute the program instructions stored in the memory to implement the color correction method according to any one of claims 1 to 9.

11. A computer-readable storage medium, characterized in that a computer program is stored thereon for implementing the color correction method of any one of claims 1 to 9.