Display brightness and chrominance correction method and system

Abstract

The invention discloses a display brightness and chrominance correction method and system, and the method comprises the steps: obtaining the brightness and chrominance values, actually measured by a brightness and chrominance meter, of red, green, blue and white under different PWM when a display displays a preset image; calculating a theoretical target display gamma curve; for the white bright color value of each level of theoretical gamma target in the theoretical target display gamma curve, obtaining actually measured red, green and blue color coordinates under the PWM value corresponding to the actually measured white brightness value which is the same as the white bright color value; calculating the target red-green-blue brightness value of each level of theoretical gamma; and searching the actually measured red, green and blue brightness value closest to the red, green and blue brightness value of each level of theoretical gamma target, acquiring a PMM value corresponding to the actually measured red, green and blue brightness value closest to the red, green and blue brightness value of each level of theoretical gamma target, forming a mapping relation, and outputting a lookup table of gamma correction. Therefore, the display can be accurately corrected.

Description

Technical Field

[0001] The present application relates to the field of display testing technology, and in particular to a display brightness and chromaticity correction method and system. Background Art

[0002] In recent years, display technology has made rapid progress, and the development of high-density and small-pitch LED displays is particularly obvious. The improvement in display effects has also attracted much attention. In the field of LED display, due to the different LED driver chips used in different displays, the grayscale transition effects presented vary greatly. There are generally uneven grayscale changes such as gray jumps and stripes. In addition, some displays also have large deviations from the standard gamma value and grayscale transition color cast, which do not meet the best viewing effect for the human eye.

[0003] In addition, since LED displays are composed of self-luminous dot matrices, they have higher display brightness and contrast than traditional CRT and LCD displays. In the prior art, even if a standard brightness colorimeter is used for measurement, there is still a certain amount of error. The color of the display is measured by a brightness colorimeter that meets industry standards, and the relationship between the input image and the actual measurement is established to perform correction. However, even if a standard brightness colorimeter is used for measurement, there is still a certain amount of error. These errors may affect the accurate evaluation of the performance of the LED display, making it impossible to accurately calibrate the LED display. Summary of the invention

[0004] Based on this, in view of the above technical problems, a display brightness and chromaticity correction method and system are provided to solve the problem that the prior art cannot accurately calibrate the LED display.

[0005] In a first aspect, a display brightness and chromaticity correction method is provided, the method comprising:

[0006] Get the brightness and chromaticity values ​​of red, green, blue and white under different PWM conditions, which are actually measured by the brightness and chromaticity meter when the monitor displays the preset picture;

[0007] Calculate the theoretical target display gamma curve based on the actual measured white brightness chromaticity values ​​at different PWMs;

[0008] For the white brightness chromaticity value of each theoretical gamma target level in the theoretical target display gamma curve, obtain the measured red, green and blue color coordinates under the PWM value corresponding to the same measured white brightness value; calculate the red, green and blue brightness value of each theoretical gamma target level based on the measured red, green and blue color coordinates corresponding to the measured white brightness value that is the same as the white brightness value of each theoretical gamma target level and the theoretical white brightness chromaticity value;

[0009] Find the actual measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level, and obtain the PMM values ​​corresponding to the actual measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level, form a mapping relationship between the PMM values ​​corresponding to the actual measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level, and output a gamma correction lookup table.

[0010] In the above scheme, optionally, after obtaining the brightness and chromaticity values ​​of red, green, blue and white actually measured by the brightness and chromaticity meter under different PWM, it also includes: preprocessing the actually measured brightness and chromaticity values ​​of red, green, blue and white under different PWM, and the preprocessing includes: background removal operation, filtering, and filtering abnormal values.

[0011] In the above scheme, further optionally, after preprocessing the actually measured brightness and chromaticity values ​​of red, green, blue and white under different PWM, it also includes: linearly interpolating the actually measured brightness and chromaticity values ​​of red, green, blue and white under different PWM to obtain continuous brightness and chromaticity values ​​of red, green, blue and white with different PWM distributions.

[0012] In the above scheme, further optionally, after obtaining the brightness chromaticity values ​​of red, green, blue and white actually measured by the brightness colorimeter under different PWM, it also includes: calculating the theoretical white brightness chromaticity value according to the actually measured red, green and blue brightness chromaticities under the same PWM, and using the theoretical white brightness chromaticity value to correct the actually measured white chromaticity value.

[0013] In the above solution, optionally, the step of calculating the theoretical target display gamma curve based on the actual measured white brightness chromaticity value at maximum PWM includes:

[0014] The white brightness chromaticity value at the maximum PWM obtained according to the actual measurement is used as the target value at the maximum brightness;

[0015] Select any curve as the target display gamma curve, the curve includes: HDR, HLG or PQ perception curve;

[0016] The target gamma curve uses a piecewise function and a linear function near 0, wherein the slope of the linear function is determined by the minimum quantization accuracy of the display; the middle and high parts are theoretical curves, and the segmented parts are made continuous and smooth.

[0017] In the above solution, further optionally, the piecewise function meets the following requirements:

[0018]

[0019] f a (x 0 ) = fb (x 0 )

[0020] y=f a (x),x≤x 0

[0021] y=f b (x),x>x 0

[0022] To ensure that the piecewise function is 0 Make sure the gamma curves are equal in the middle and high areas:

[0023]

[0024] Among them, f a is a linear function, f b is the theoretical curve.

[0025] In the above solution, optionally, the calculation of each level of theoretical gamma target red, green and blue brightness value is performed by the following formula:

[0026]

[0027] The conversion formula between XYZ and cx, cy, Y is:

[0028]

[0029] Y=Y

[0030]

[0031] Among them, X w , Y w , Z w is the theoretical white brightness chromaticity value; R cx , R cy , G cx , G cy , B cx , B cy , are the RGB color coordinates.

[0032] In a second aspect, a display brightness and chromaticity correction system is provided, the system comprising:

[0033] Data acquisition module: used to obtain the brightness and chromaticity values ​​of red, green, blue and white actually measured by the brightness and chromaticity meter under different PWM when the display displays the preset picture;

[0034] Theoretical target display gamma curve calculation module: used to calculate the theoretical target display gamma curve based on the actual measured white brightness chromaticity values ​​at different PWMs;

[0035] Theoretical gamma target red, green and blue brightness value calculation module: used for obtaining the measured red, green and blue color coordinates under the PWM value corresponding to the same measured white brightness value for each level of the theoretical gamma target in the theoretical target display gamma curve; calculating the red, green and blue brightness value of each level of the theoretical gamma target based on the measured red, green and blue color coordinates corresponding to the measured white brightness value that is the same as the white brightness value of each level of the theoretical gamma target and the theoretical white brightness chromaticity value;

[0036] Gamma correction table output module: used to find the actual measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level, and obtain the PMM values ​​corresponding to the actual measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level, form a mapping relationship between the PMM values ​​corresponding to the actual measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level and the theoretical gamma target red, green, and blue brightness values ​​of each level, and output the gamma correction lookup table.

[0037] In a third aspect, a computer device includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of a display brightness and chromaticity correction method described in the first aspect are implemented.

[0038] In a fourth aspect, a computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of a display brightness and chromaticity correction method described in the first aspect are implemented.

[0039] This application has at least the following beneficial effects:

[0040] The present application measures the brightness chromaticity values ​​of red, green, blue and white under different PWMs, calculates the theoretical target display gamma curve based on the brightness chromaticity value of white at different PWMs actually measured, obtains the measured red, green and blue color coordinates under the PWM value corresponding to the same measured white brightness value, and then calculates the red, green and blue brightness value of each theoretical gamma target by the measured red, green and blue color coordinates corresponding to the measured white brightness value of each theoretical gamma target and the theoretical white brightness value, thereby overcoming the influence of a certain amount of error in the measurement using a standard brightness colorimeter. The PMM value corresponding to the actually measured red, green and blue brightness value closest to the red, green and blue brightness value of each theoretical gamma target is mapped to the red, green and blue brightness value of each theoretical gamma target, and a gamma-corrected lookup table is output. In this way, the desired picture can be accurately output through the gamma correction mapping table. Through this method, accurate calibration of the display can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of a flow chart of a display brightness and chromaticity correction method provided in one embodiment of the present application;

[0042] Figure 2 A detailed flow chart of a display brightness and chromaticity correction method is provided for one embodiment of the present application;

[0043] Figure 3 A schematic diagram of using the HLG curve as a theoretical target display gamma curve is provided for one embodiment of the present application. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0045] In one embodiment, Figure 1 As shown, a display brightness and chromaticity correction method is provided, comprising the following steps:

[0046] Step S1: obtaining the brightness and chromaticity values ​​of red, green, blue and white actually measured by the brightness and chromaticity meter under different PWM when the display displays a preset picture.

[0047] In step S1, a standard brightness colorimeter is connected to a main control device such as a computer to measure the step-by-step PWM brightness and chromaticity values ​​of the red, green, blue and white (RGBW) of the display panel. The measurement time can also be reduced by adjusting the sampling PWM interval, but when the interval sampling is performed, the interval value needs to be restored by interpolation in subsequent processing.

[0048] After step S1, after receiving the measured RGBW brightness and chromaticity values, the background removal operation is first performed, that is, each level of measurement value is subtracted from the measurement value when the PWM signal is 0 or the screen is black, and then filtered to remove abnormal points such as measurement errors or noise glitches, in order to reduce the deviation caused by measurement accuracy or stability. In general, as PWM increases, the measured brightness increases accordingly. Therefore, by judging whether the current value is greater than the previous PWM brightness value in the adjacent range and less than the subsequent PWM brightness value, the measured data can be traversed in sequence to remove abnormal values. As for the chromaticity color coordinates, considering that there will be no sudden changes in the color coordinates of the single color, the processing uses a smoothing method, such as median filtering, mean filtering, etc.

[0049] Then, the PWM-brightness sampled at previous intervals and the values ​​eliminated due to abnormalities are interpolated to obtain the RGBW brightness and chromaticity data of continuous PWM distribution.

[0050] At the same time, since the brightness and chromaticity of the actual measured white is not equal to the brightness and chromaticity value of the theoretically calculated white, the measured value is corrected by calculating the theoretical white. Given the brightness and chromaticity data of the RGB measurement, the formula for calculating the brightness and chromaticity of the theoretical white is as follows:

[0051] X r +X g +X b =X w

[0052] Y r +Y g +Y b =Y w

[0053] Z r +Z g +Z b =Z w

[0054] Among them, XYZ is the tristimulus value of the three primary colors RGB, and the subscript represents the color.

[0055] Step S2: Calculate the theoretical target display gamma curve based on the actually measured white brightness chromaticity values ​​at different PWMs.

[0056] First, the white brightness chromaticity value at the maximum PWM is measured as the target value at the maximum brightness to keep the white field brightness chromaticity unchanged after gamma correction. Then a target curve is selected as the gamma curve. For example, for LED screens, a standard curve with a gamma of 2.8 is selected, or for LED screens with a maximum brightness that meets the HDR standard, the HLG or PQ perception curve is used as the target gamma curve. Figure 3 The figure shows a segmented gamma curve calculated by using the HLG curve as the target gamma curve and combining it with the measured minimum hardware quantization accuracy.

[0057] In particular, the target gamma curve can use a piecewise function, for example, a linear function is used near 0, and the slope is determined by the minimum quantization accuracy of the display; the middle and high parts are theoretical curves, and the segments are continuous and smooth. Then the piecewise function meets the following requirements:

[0058]

[0059] f a (x 0 ) = f b (x 0 )

[0060] y=f a (x),x≤x 0

[0061] y=f b(x),x>x 0

[0062] At the same time, to ensure that the piecewise function is 0 At the same place, adjust the mid-high gray gamma curve:

[0063]

[0064] Among them, f a is a linear function, f b is the theoretical curve.

[0065] Step S3: for the white brightness chromaticity value of each theoretical gamma target level in the theoretical target display gamma curve, obtain the measured red, green and blue color coordinates under the PWM value corresponding to the same measured white brightness value; calculate the red, green and blue brightness value of each theoretical gamma target level based on the measured red, green and blue color coordinates corresponding to the measured white brightness value that is the same as the white brightness value of each theoretical gamma target level and the theoretical white brightness chromaticity value;

[0066] In step S3, the sequence number of the white brightness value of each level of theoretical gamma target in the interpolated PWM white brightness chromaticity is traversed to obtain the RGB color coordinates under the sequence number. The brightness of the RGB primary colors is calculated by the output RGB color coordinates and the brightness and color coordinates of the target white of each level of theoretical gamma.

[0067]

[0068] The conversion formula between XYZ and cx, cy, Y is:

[0069]

[0070] Y=Y

[0071]

[0072] Among them, X w , Y w , Z w is the theoretical white brightness chromaticity value; R cx , R cy , G cx , G cy , B cx , B cy , are the RGB color coordinates.

[0073] Step S4: Find the actually measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level, and obtain the PMM values ​​corresponding to the actually measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level, form a mapping relationship between the PMM values ​​corresponding to the actually measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level, and output the gamma correction lookup table.

[0074] In this step, the purpose is to find the PWM of the RGB brightness generated in the previous module that is closest to the value in the aforementioned PWM-brightness interpolation data, and output the lookup table for RGB as a gamma correction mapping table, which is sent to the hardware. Therefore, according to the gamma correction mapping table, the PWM value is adjusted according to the brightness and chromaticity that are actually output.

[0075] In the above-mentioned display brightness chromaticity correction method, by actually measuring the brightness chromaticity values ​​of red, green, blue and white under different PWM, the theoretical target display gamma curve is calculated based on the brightness chromaticity value of white at different PWMs actually measured, and the white brightness value of each theoretical gamma target in the theoretical target display gamma curve is used to obtain the measured red, green and blue color coordinates under the PWM value corresponding to the same measured white brightness value, and then the measured red, green and blue color coordinates corresponding to the measured white brightness value of each theoretical gamma target and the theoretical white brightness value are used to calculate the red, green and blue brightness value of each theoretical gamma target, thereby overcoming the influence of a certain amount of error in the measurement using a standard brightness colorimeter. The PMM value corresponding to the actually measured red, green and blue brightness value closest to the red, green and blue brightness value of each theoretical gamma target is mapped to the red, green and blue brightness value of each theoretical gamma target, and a gamma correction lookup table is output. In this way, the desired picture can be accurately output through the gamma correction mapping table. Through this method, accurate calibration of the display can be achieved.

[0076] In one embodiment, a display brightness and chromaticity correction system is provided, the system comprising:

[0077] Data acquisition module: used to obtain the brightness and chromaticity values ​​of red, green, blue and white actually measured by the brightness and chromaticity meter under different PWM when the display displays the preset picture;

[0078] Theoretical target display gamma curve calculation module: used to calculate the theoretical target display gamma curve based on the actual measured white brightness chromaticity values ​​at different PWMs;

[0079] Theoretical gamma target red, green and blue brightness value calculation module: used for obtaining the measured red, green and blue color coordinates under the PWM value corresponding to the same measured white brightness value for each level of the theoretical gamma target in the theoretical target display gamma curve; calculating the red, green and blue brightness value of each level of the theoretical gamma target based on the measured red, green and blue color coordinates corresponding to the measured white brightness value that is the same as the white brightness value of each level of the theoretical gamma target and the theoretical white brightness chromaticity value;

[0080] Gamma correction table output module: used to find the actual measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level, and obtain the PMM values ​​corresponding to the actual measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level, form a mapping relationship between the PMM values ​​corresponding to the actual measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level and the theoretical gamma target red, green, and blue brightness values ​​of each level, and output the gamma correction lookup table.

[0081] For the specific definition of a display brightness and chromaticity correction system, please refer to the definition of a display brightness and chromaticity correction method mentioned above, which will not be repeated here. Each module in the above-mentioned display brightness and chromaticity correction system can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0082] In one embodiment, a computer device is provided, which may be a server. The computer device includes a processor, a memory, and a network interface connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, the above-mentioned display brightness and chromaticity correction method is implemented.

[0083] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored, which involves all or part of the processes in the above-mentioned embodiment method.

[0084] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0085] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0086] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A display brightness and chromaticity correction method, characterized in that: The method comprises: Get the brightness and chromaticity values ​​of red, green, blue and white under different PWM conditions, which are actually measured by the brightness and chromaticity meter when the monitor displays the preset picture; Calculate the theoretical target display gamma curve based on the actual measured white brightness chromaticity values ​​at different PWMs; For the white brightness chromaticity value of each theoretical gamma target level in the theoretical target display gamma curve, obtain the measured red, green and blue color coordinates under the PWM value corresponding to the same measured white brightness value; calculate the red, green and blue brightness value of each theoretical gamma target level based on the measured red, green and blue color coordinates corresponding to the measured white brightness value that is the same as the white brightness value of each theoretical gamma target level and the theoretical white brightness chromaticity value; Find the actual measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level, and obtain the PMM values ​​corresponding to the actual measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level, form a mapping relationship between the PMM values ​​corresponding to the actual measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level, and output a gamma correction lookup table.

2. The display brightness and chromaticity correction method according to claim 1, characterized in that: After obtaining the brightness and chromaticity values ​​of red, green, blue and white actually measured by the brightness and chromaticity meter under different PWM, the method further includes: preprocessing the brightness and chromaticity values ​​of red, green, blue and white actually measured under different PWM, wherein the preprocessing includes: background removal operation, filtering, and filtering abnormal values.

3. The display brightness and chromaticity correction method according to claim 2, characterized in that: After preprocessing the actually measured red, green, blue and white brightness and chromaticity values ​​under different PWM, the method further includes: linearly interpolating the actually measured red, green, blue and white brightness and chromaticity values ​​under different PWM to obtain continuous red, green, blue and white brightness and chromaticity values ​​with different PWM distributions.

4. The display brightness and chromaticity correction method according to claim 3, characterized in that: After obtaining the brightness chromaticity values ​​of red, green, blue and white actually measured by the brightness colorimeter under different PWMs, the method further includes: calculating a theoretical white brightness chromaticity value according to the actually measured red, green and blue brightness chromaticities under the same PWM, and using the theoretical white brightness chromaticity value to correct the actually measured white brightness chromaticity value.

5. The display brightness and chromaticity correction method according to claim 1, characterized in that: The calculation of the theoretical target display gamma curve based on the actual measured white brightness chromaticity value at the maximum PWM time comprises: The white brightness chromaticity value at the maximum PWM obtained according to the actual measurement is used as the target value at the maximum brightness; Select any curve as the target display gamma curve, the curve includes: HDR, HLG or PQ perception curve; The target gamma curve uses a piecewise function and a linear function near 0, wherein the slope of the linear function is determined by the minimum quantization accuracy of the display; the middle and high parts are theoretical curves, and the segmented parts are made continuous and smooth.

6. The display brightness and chromaticity correction method according to claim 5, characterized in that: The piecewise function meets the following requirements: f a (x0)=f b (x0) y=f a (x),x≤x0 y=f b (x),x>x0 To ensure that the piecewise functions are equal at x0, adjust the gamma curve in the middle and high places: Among them, f a is a linear function, f b is the theoretical curve.

7. The display brightness and chromaticity correction method according to claim 1, characterized in that: The calculation of the theoretical gamma target red, green and blue brightness values ​​for each level is done by the following formula: The conversion formula between XYZ and cx, cy, Y is: Y=Y Among them, X w , Y w , Z w is the theoretical white brightness chromaticity value; R cx , R cy , G cx , G cy , B cx , B cy , are the RGB color coordinates.

8. A display brightness and chromaticity correction system, characterized in that: The system comprises: Data acquisition module: used to obtain the brightness and chromaticity values ​​of red, green, blue and white actually measured by the brightness and chromaticity meter under different PWM when the display displays the preset picture; Theoretical target display gamma curve calculation module: used to calculate the theoretical target display gamma curve based on the actual measured white brightness chromaticity values ​​at different PWMs; Theoretical gamma target red, green and blue brightness value calculation module: used for obtaining the measured red, green and blue color coordinates under the PWM value corresponding to the same measured white brightness value for each level of the theoretical gamma target in the theoretical target display gamma curve; calculating the red, green and blue brightness value of each level of the theoretical gamma target based on the measured red, green and blue color coordinates corresponding to the measured white brightness value that is the same as the white brightness value of each level of the theoretical gamma target and the theoretical white brightness chromaticity value; Gamma correction table output module: used to find the actual measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level, and obtain the PMM values ​​corresponding to the actual measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level, form a mapping relationship between the PMM values ​​corresponding to the actual measured red, green, and blue brightness values ​​that are closest to the theoretical gamma target red, green, and blue brightness values ​​of each level and the theoretical gamma target red, green, and blue brightness values ​​of each level, and output the gamma correction lookup table.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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