Method and system for correcting low-gray color distortion, product, equipment and storage medium

Abstract

The invention discloses a low-gray color distortion correction method and system, a product, equipment and a storage medium, belongs to the technical field of LED display screen correction, and solves the technical problem of color distortion existing in low-gray-scale display of an LED display image in the prior art. The method comprises the following steps: step 1, acquiring an RGB color system of an LED display screen, and converting the RGB color system of the LED display screen into an xyY color space to obtain a deviation database; step 2, constructing a compensation coefficient lookup table based on the deviation database; and step 3, based on the compensation coefficient lookup table, performing color jitter on the real-time image displayed by the LED display screen, and performing chromatic aberration correction on the real-time image displayed by the LED display screen after color jitter to obtain an LED display image after chromatic aberration correction. The method is used for improving the color of the LED display screen and restoring the precision of the LED display screen.

Description

Technical Field

[0001] The present invention relates to the technical field of LED display screen correction, and in particular to a correction method, system, product, device and storage medium for base low-gray color distortion. Background Art

[0002] LED (light-emitting diode) display is a common display technology. By transmitting the desired image to an LED screen for display, it creates richer, more vivid displays with a strong visual impact. Currently widely used in science and technology exhibitions, advertising campaigns, and creative showcases, it can freely play programs combining videos, text, and images, and disseminate information in a real-time, synchronized, and clear manner. However, current LED screens are prone to chromatic aberration and nonlinear brightness response at low grayscale levels, resulting in color distortion and discontinuous grayscale transitions in dark scenes.

[0003] Current LED display color calibration typically involves global calibration. While this method offers the advantages of speed and convenience, it also has significant drawbacks. Traditional calibration methods often rely on global gamma curve compensation, which struggles to adapt to variations in driver chips and aging LEDs. Using only a single gamma curve to simulate the human visual characteristic curve significantly increases low-grayscale color distortion with increasing contrast, making it impossible to accurately correct color for each grayscale level. Furthermore, this method fails to protect certain human memory colors, resulting in reddish skin tones. LED displays using a single gamma curve also have significant technical limitations, primarily in terms of poor match between optoelectronic characteristics and visual perception. Due to the quantum efficiency differences among the three-channel R / G / B (red / green / blue) LED chips and the nonlinear response characteristics of the driver IC (integrated circuit), such as the steep drop in efficiency of red light at low currents, a fixed gamma curve can lead to severe color and brightness distortion in the low-grayscale range, disrupting grayscale continuity. Furthermore, according to the Weber-Fechner law, the human eye's sensitivity to low-brightness areas doesn't match the characteristics of a single index, resulting in a loss of visual separability in some grayscales and significantly impacting the ability to reproduce HDR (high dynamic range) content. Furthermore, without considering the impact of LED wavelength batch drift and dynamic changes in ambient light, a single correction can amplify color temperature deviations between modules, impacting the user's viewing experience of the LED display.

[0004] In the prior art, Chinese patent document CN114067731A discloses a "method, device, and brightness correction system for low-grayscale correction of LED displays." The method sequentially obtains a preset grayscale setting value n and LED display brightness data for each grayscale below the grayscale setting value n. In the LED display brightness data, each light point on the LED display corresponds to n display brightness values. From the n display brightness values corresponding to the light point to be corrected, the method selects grayscale value i, the display brightness value Pi corresponding to grayscale value i+1, and the display brightness value Pi+1. A target brightness value is set using the display brightness value Pi and the display brightness value Pi+1. The method also calculates the brightness compensation value b for the light point to be corrected using a preset brightness compensation value calculation strategy and the target brightness value, display brightness value Pi+1, display brightness value Pi, grayscale setting value n, and grayscale value i. However, this technical solution only corrects low-grayscale brightness and does not consider the impact of LED wavelength batch drift and dynamic changes in ambient light. This single correction can amplify color temperature deviations between modules, affecting the user's viewing experience of the LED screen.

[0005] In summary, the prior art has the technical problem of color distortion in low grayscale display of LED display images. Summary of the Invention

[0006] The present invention solves the technical problem of color distortion in low grayscale display of LED display images in the prior art.

[0007] The method for correcting low-grayscale color distortion of the present invention comprises the following steps: Step 1: Obtain the RGB color system of the LED display screen, convert the RGB color system of the LED display screen into the xyY color space, and obtain a deviation database; Step 2: construct a compensation coefficient lookup table based on the deviation database; Step 3: Based on the compensation coefficient lookup table, color dithering is performed on the real-time image displayed on the LED display screen, and color difference correction is performed on the real-time image displayed on the LED display screen after color dithering to obtain an LED display image after color difference correction.

[0008] Furthermore, in the embodiment of the present invention, the RGB color system of the LED display screen is converted into the xyY color space in step 1 to obtain the deviation database, specifically: Get the color gamut conversion parameters when the RGB color system of the LED display is converted to the xyY color space, and get the actual color of the LED display after the color gamut conversion. The color deviation between the actual color of the LED display after the color gamut conversion and the theoretical color after the color gamut conversion of the LED display is specifically: ; ; ; in, In xyY space Parameter deviation data value, is the truncation function, In xyY space Parameter deviation data value, To control the system accuracy, In xyY space Parameter deviation data value, 、 and is the brightness value of the three primary colors after gamma correction, and is the xyY color space coordinate of red, and is the xyY color space coordinate of green, and is the xyY color space coordinate of blue, 、 、 、 、 、 、 、 and are different color gamut conversion parameters, is the vertical coordinate in the RGB color system before conversion, is the vertical coordinate in the converted xyY color space, For the The quantized value of the red brightness correction parameter of each pixel, and Different The quantized value of the green brightness correction parameter of each pixel, and Different Quantized value of the blue brightness correction parameter of each pixel; The color deviation between the actual color after the LED display screen color gamut conversion and the theoretical color after the LED display screen color gamut conversion is used as the deviation database.

[0009] Furthermore, in an embodiment of the present invention, the compensation coefficient lookup table in step 2 includes brightness compensation coefficients and correction parameters.

[0010] Furthermore, in the embodiment of the present invention, the color dithering of the real-time image displayed on the LED display screen in step 3 is specifically performed as follows: The real-time image displayed on the LED display is evenly divided into multiple pixel windows, and the color deviations in the multiple pixel windows are diffused to adjacent pixel windows to obtain the real-time image displayed on the LED display after color dithering.

[0011] The low gray color distortion correction system of the present invention includes the following modules: The conversion module obtains the RGB color system of the LED display screen, converts the RGB color system of the LED display screen into the xyY color space, and obtains a deviation database; A construction module constructs a compensation coefficient lookup table based on the deviation database; The correction module performs color dithering on the real-time image displayed on the LED display screen based on the compensation coefficient lookup table, and performs color difference correction on the real-time image displayed on the LED display screen after color dithering to obtain an LED display image after color difference correction.

[0012] A computer program product according to the present invention includes a computer program or an instruction, and is characterized in that when the computer program or the instruction is executed by a processor, any of the above-mentioned methods for correcting low-gray color distortion is implemented.

[0013] An electronic device according to the present invention comprises a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus; Memory for storing computer programs; The processor is configured to implement any of the above-mentioned methods for correcting low-gray color distortion when executing a program stored in the memory.

[0014] A computer-readable storage medium according to the present invention is characterized in that a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, any of the above-mentioned methods for correcting low-gray color distortion is implemented.

[0015] A display screen according to the present invention is characterized in that the display screen adopts any of the above-mentioned low-gray color distortion correction methods to achieve correction of low-gray color distortion.

[0016] The present invention solves the technical problem of color distortion in low grayscale display of LED display images in the prior art. Specific beneficial effects include: 1. The method for correcting low-gray color distortion proposed in the present invention models the LED display screen to obtain the color information of all pixels on the screen, performs theoretical calculations on the low-gray color information of the LED display screen, and uses the color deviation characteristics of each grayscale obtained by theoretical calculations to construct a compensation coefficient lookup table. The real-time image displayed by the LED display screen is color-dithered, and complementary colors are assigned in the spatial domain. The real-time image displayed by the color-dithered LED display screen is then color-corrected. Intelligent pixel-level control is achieved through color dithering, which improves the color of the LED display screen and restores the accuracy of the LED display screen, thereby improving the low-gray color cast problem of the LED display screen, significantly improving the accuracy of low-grayscale color restoration, and effectively correcting the color distortion phenomenon existing in the low-grayscale display of LED display images. 2. The low-gray color distortion correction method proposed in the present invention converts the inherent deviation caused by the control system accuracy limitation into a system error that can be compensated by spatial modulation, diffuses the deviation of each pixel into a 2*2 pixel window, and realizes color dithering through an improved error diffusion algorithm. The overall display accuracy is improved through the synergy between pixels. The improved error diffusion algorithm adopts configurable pixel window size and diffusion coefficient, and can optimize parameters according to the characteristics of different display modules. While maintaining the details of the original image, it effectively improves the color expression of low grayscale areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which: Figure 1 This is a schematic diagram of color mixing in the LED display screen according to the first embodiment; Figure 2 This is a schematic diagram of the color distortion phenomenon caused by the control system accuracy problem described in the first embodiment; Figure 3 2 is a schematic diagram of the color dithering window described in the fourth embodiment. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe various embodiments of the present invention in conjunction with the accompanying drawings. The embodiments described with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0019] Implementation 1. The method for correcting low-gray color distortion according to this implementation comprises the following steps: Step 1: Obtain the RGB color system of the LED display screen, convert the RGB color system of the LED display screen into the xyY color space, and obtain a deviation database; Step 2: construct a compensation coefficient lookup table based on the deviation database; Step 3: Based on the compensation coefficient lookup table, color dithering is performed on the real-time image displayed on the LED display screen, and color difference correction is performed on the real-time image displayed on the LED display screen after color dithering to obtain an LED display image after color difference correction.

[0020] The existing technology has the technical problem of color distortion in low grayscale display of LED display images.

[0021] To address the aforementioned technical issues, this embodiment provides a method for correcting low-grayscale color distortion. This method collects the RGB color system of an LED display image at low grayscale, combines it with the CIE (International Commission on Illumination) chromaticity coordinate theoretical model, constructs a nonlinear color gamut mapping relationship for each pixel, generates a compensation coefficient matrix, and applies this compensation coefficient to the control system to compensate for the low-grayscale color distortion problem of the LED display image. Specifically, the method includes the following steps: Step 1: geometrically model the sub-pixels of the LED display screen, and obtain the color information of each grayscale pixel of the LED display screen by dividing the R / G / B channels. Convert the RGB color system into the xyY color space. The color of each pixel is expressed as ( ).

[0022] The color mixing principle of LED display screen complies with the Grassmann color matching principle. The color mixing method in LED display screen is as follows: Figure 1 shown.

[0023] First, based on the geometric modeling data of the LED display, the spatial position information of each sub-pixel is accurately obtained; then, the RGB color of each sub-pixel is calculated. After that, the RGB color system is converted to the xyY color space through the established color space conversion matrix. The conversion formula is: ; ; ; ; in, is the transformation matrix, is the color coordinate in the converted xyY color space, is the input RGB color coordinate, and are the x and y coordinates in the xyY color space, respectively. is the brightness coordinate.

[0024] However, in actual applications, due to the accuracy problem of the control system, low-gray colors cannot be mixed, and low-gray color distortion occurs, such as Figure 2As shown, therefore, by calculating the color deviation of each gray level in the low gray part due to the accuracy of the control system, a basis is provided for the subsequent color dithering.

[0025] Step 2: construct a compensation coefficient lookup table based on the deviation database; Step 3: Based on the compensation coefficient lookup table, color dithering is performed on the real-time image displayed on the LED display screen, and color difference correction is performed on the real-time image displayed on the LED display screen after color dithering to obtain an LED display image after color difference correction; Combining the human visual perception model, chromatic aberration correction is performed in the xyY color space to ensure that the color transition between adjacent pixels is natural and smooth after spatial dithering, which conforms to the spatial integration characteristics of the visual system.

[0026] Therefore, this embodiment uses the color deviation characteristics of each grayscale obtained by theoretical calculation to select a pixel window in the xyY color space of the real-time image displayed on the LED display screen for adaptive spatial color dithering processing, that is, the deviation of each pixel is diffused to the adjacent pixel window, and complementary colors are distributed in the spatial domain to achieve color dithering in the xyY color space. Through intelligent pixel-level regulation, the color of the LED display screen is improved and the accuracy of the LED display screen is restored, the overall color accuracy of the LED display screen is improved, the color difference is reduced, and the accuracy of low-grayscale color restoration is improved, solving the technical problem of color distortion in low-grayscale display of LED display images in the existing technology.

[0027] Implementation 2. This implementation is a further limitation of the low gray color distortion correction method described in Implementation 1. In step 1, the RGB color system of the LED display is converted into an xyY color space to obtain a deviation database, specifically: Get the color gamut conversion parameters when the RGB color system of the LED display is converted to the xyY color space, and get the actual color of the LED display after the color gamut conversion. The color deviation between the actual color of the LED display after the color gamut conversion and the theoretical color after the color gamut conversion of the LED display is specifically: ; ; ; in, is the x parameter deviation data value in the xyY space, is the truncation function, is the Y parameter deviation data value in the xyY space, To control the system accuracy, is the y parameter deviation data value in the xyY space, 、 、 is the brightness value of the three primary colors after gamma correction, 、 is the xyY color space coordinate of red, 、 is the xyY color space coordinate of green, 、 is the xyY color space coordinate of blue, 、 、 、 、 、 、 、 、 is the color gamut conversion parameter, is the vertical coordinate in the RGB color system before conversion, is the vertical coordinate in the converted xyY color space, For the The quantized value of the red brightness correction parameter of each pixel, and Different The quantized value of the green brightness correction parameter of each pixel, and Different Quantized value of the blue brightness correction parameter of each pixel; The color deviation between the actual color after the LED display screen color gamut conversion and the theoretical color after the LED display screen color gamut conversion is used as the deviation database.

[0028] In actual display, the LED display is composed of pixels. When the LED display performs color gamut conversion, the color difference function model of each pixel is fixed. One set of color gamut conversion parameters includes nine color gamut conversion parameters of the pixel, with the first Taking the red conversion parameter of a pixel as an example, it can be expressed as 、 、 、 、 、 、 、 and The color gamut conversion matrix of each pixel is related to the above nine color gamut conversion parameters. The value of the color gamut conversion parameter depends on the base color original color gamut RGB color system and the given target conversion color gamut xyY color space. These nine color gamut conversion parameters are discrete, and the value range of all color gamut conversion parameters is (0, 1]. When performing color gamut conversion calculations, since the control system is discrete and not continuous, the calculated data must be quantized. The specific quantization accuracy depends on the control accuracy of the display device. The correction parameters of each pixel can be expressed as: ; in, is the calibration parameter, 、 、 、 、 、 、 、 、 It is the color gamut conversion parameter.

[0029] The correction parameters of each pixel are calculated based on the color gamut conversion relationship, and the actual color of each pixel after color gamut conversion can be obtained as follows: ; ; ; ; in, For the pixels, is the brightness value after conversion, ‌、 ‌、 The horizontal, vertical, and depth coordinates in the converted xyY color space, is the truncation function, which is used to simulate the truncation error generated by the control system. 、 、 is the brightness value of the three primary colors after gamma correction, 、 、 is the xyY color space coordinate of red, 、 、 is the xyY color space coordinate of green, 、 、 The xyY color coordinate of blue.

[0030] Under the influence of quantization error, there is a deviation between the actual color after the LED display color gamut conversion and the theoretical color after the LED display color gamut conversion. The expression of the color deviation between the two is: ; ; in, In xyY space Parameter deviation data value, In xyY space Parameter deviation data value.

[0031] and The larger the value, the more obvious the quantization error is, which will cause the color uniformity of the LED display to fail to meet the viewing standard after the color gamut conversion. Therefore, in order to improve the viewing effect of the color of the LED display after conversion, the deviation value between the two must be reduced. Combining the above formula, we can get: ; ; in, In xyY space Parameter deviation data value, For the control system accuracy.

[0032] Implementation method three. This implementation method is a further limitation of the low-gray color distortion correction method described in Implementation method one, and the compensation coefficient lookup table in step 2 includes a brightness compensation coefficient and a correction parameter.

[0033] Based on the PWM (pulse width modulation) quantization model and the deviation database established by the nonlinear driving characteristics in step 1, a LUT (compensation coefficient lookup table) containing the grayscale compensation parameters of each of the three channels is constructed. By collecting the pixel information of the LED display screen point by point, the full-screen brightness coefficient is obtained. The central trend of the data set is determined and the compensation parameters of each pixel are calculated to obtain the brightness compensation coefficient. The LUT contains not only the brightness compensation coefficient but also the correction parameters.

[0034] The PWM quantization model first discretizes and samples the continuous-time analog signal based on the Nyquist sampling theorem to obtain instantaneous amplitude samples. Then, the amplitude value of each sample is mapped to a discrete level of finite precision through a uniform or non-uniform quantizer, that is, an amplitude that is an integer multiple of the quantization step is assigned. The quantized amplitude is converted into a pulse sequence corresponding to the duty cycle. The pulse width and the quantization level are linearly mapped, which is usually achieved by a counter comparison mechanism. The final output PWM wave is reconstructed into a quantized analog signal through a low-pass filter. Its quantization error is manifested in the time domain as a discrete deviation of the pulse width. Implementation 4. This implementation is a further limitation of the low gray color distortion correction method described in Implementation 1. The color dithering of the real-time image displayed on the LED display in step 3 is specifically as follows: The real-time image displayed on the LED display is evenly divided into multiple pixel windows, and the deviation of each pixel in the deviation database is diffused to adjacent pixel windows to obtain the real-time image displayed on the LED display after color dithering.

[0035] like Figure 3 As shown, in the real-time image processing link, the control system performs pixel-level analysis on the input signal and uses an improved error diffusion algorithm to perform dynamic adjustment for each 2*2 pixel window. The quantization error of the target pixel is intelligently distributed to the adjacent pixel windows through complementary pixel brightness distribution in the spatial domain. The improved error diffusion algorithm is an existing technology.

[0036] Implementation 5. The low gray color distortion correction system described in this implementation includes the following modules: The conversion module obtains the RGB color system of the LED display screen, converts the RGB color system of the LED display screen into the xyY color space, and obtains a deviation database; A construction module constructs a compensation coefficient lookup table based on the deviation database; The correction module performs color dithering on the real-time image displayed on the LED display screen based on the compensation coefficient lookup table, and performs color difference correction on the real-time image displayed on the LED display screen after color dithering to obtain an LED display image after color difference correction.

[0037] Embodiment 6. A computer program product described in this embodiment includes a computer program or instructions, which, when executed by a processor, implements the method for correcting low-gray color distortion described in any one of Embodiments 1 to 4.

[0038] Embodiment 7. An electronic device described in this embodiment includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other via the communication bus; Memory for storing computer programs; The processor is configured to implement the method for correcting low-gray color distortion described in any one of embodiments one to four when executing the program stored in the memory.

[0039] Embodiment 8. The computer-readable storage medium described in this embodiment stores a computer program, and when the computer program is executed by a processor, the method for correcting low-gray color distortion described in any one of Embodiments 1 to 4 is implemented.

[0040] Embodiment 9. A display screen described in this embodiment adopts the low-gray color distortion correction method described in any one of Embodiments 1 to 4 to achieve correction of low-gray color distortion.

[0041] The above is a detailed introduction to the low-gray color distortion correction method, system, product, device and storage medium proposed in the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for correcting low gray color distortion, characterized in that: The following steps are involved: Step 1: Obtain the RGB color system of the LED display screen, convert the RGB color system of the LED display screen into the xyY color space, and obtain a deviation database; Step 2: construct a compensation coefficient lookup table based on the deviation database; Step 3: Based on the compensation coefficient lookup table, color dithering is performed on the real-time image displayed on the LED display screen, and color difference correction is performed on the real-time image displayed on the LED display screen after color dithering to obtain an LED display image after color difference correction.

2. The method for correcting low gray color distortion according to claim 1, wherein: In step 1, the RGB color system of the LED display is converted into the xyY color space to obtain a deviation database, specifically: Get the color gamut conversion parameters when the RGB color system of the LED display is converted to the xyY color space, and get the actual color of the LED display after the color gamut conversion. The color deviation between the actual color of the LED display after the color gamut conversion and the theoretical color after the color gamut conversion of the LED display is specifically: ； ； ； in, In xyY space Parameter deviation data value, is the truncation function, In xyY space Parameter deviation data value, To control the system accuracy, In xyY space Parameter deviation data value, 、 and is the brightness value of the three primary colors after gamma correction, and is the xyY color space coordinate of red, and is the xyY color space coordinate of green, and is the xyY color space coordinate of blue, 、 、 、 、 、 、 、 and are different color gamut conversion parameters, is the vertical coordinate in the RGB color system before conversion, is the vertical coordinate in the converted xyY color space, For the The quantized value of the red brightness correction parameter of each pixel, and Different The quantized value of the green brightness correction parameter of each pixel, and Different Quantized value of the blue brightness correction parameter of each pixel; The color deviation between the actual color after the LED display screen color gamut conversion and the theoretical color after the LED display screen color gamut conversion is used as the deviation database.

3. The method for correcting low gray color distortion according to claim 1, wherein: The compensation coefficient lookup table in step 2 includes brightness compensation coefficients and correction parameters.

4. The method for correcting low gray color distortion according to claim 1, wherein: The color dithering of the real-time image displayed on the LED display screen in step 3 is specifically performed as follows: The real-time image displayed on the LED display is evenly divided into multiple pixel windows, and the color deviations in the multiple pixel windows are diffused to adjacent pixel windows to obtain the real-time image displayed on the LED display after color dithering.

5. Low gray color distortion correction system, characterized by: Includes the following modules: The conversion module obtains the RGB color system of the LED display screen, converts the RGB color system of the LED display screen into the xyY color space, and obtains a deviation database; A construction module constructs a compensation coefficient lookup table based on the deviation database; The correction module performs color dithering on the real-time image displayed on the LED display screen based on the compensation coefficient lookup table, and performs color difference correction on the real-time image displayed on the LED display screen after color dithering to obtain an LED display image after color difference correction.

6. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed by a processor, the method for correcting low-gray color distortion according to any one of claims 1 to 4 is implemented.

7. An electronic device, characterized in that: It includes a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus; Memory for storing computer programs; The processor is configured to implement the method for correcting low-gray color distortion according to any one of claims 1 to 4 when executing a program stored in the memory.

8. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for correcting low-gray color distortion according to any one of claims 1 to 4 is implemented.

9. A display screen, characterized in that: The display screen adopts the low-gray color distortion correction method described in any one of claims 1 to 4 to achieve correction of low-gray color distortion.

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