Display panel Demura compensation method and system based on three-dimensional lookup table iteration

Abstract

The invention provides a display panel Demura compensation method and system based on three-dimensional lookup table iteration, and the method employs an iteration strategy to optimize compensation data based on a photographing device and a lookup table compensation scheme so as to gradually approach an optimal solution or meet specific requirements. According to the method, the problem of insufficient single compensation effect is solved, optimization can be carried out according to specific characteristics of different display panels, and the method has high universality and wide expansion potential. The method breaks through the limitation of the prior art, is not limited by a specific application type, and can maintain excellent performance and effect on different types of display panels.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of image processing, and relates to a display panel Demura compensation method and system based on three-dimensional lookup table iteration. BACKGROUND

[0002] With the continuous development of display technology, display panels are widely used in various display fields, such as televisions, mobile phones, VR / AR, vehicle-mounted devices, and monitors.

[0003] However, due to differences in manufacturing processes, material properties, and pixel structures, various display panels inevitably exhibit non-uniform brightness and chrominance, i.e., Mura phenomenon, during actual production. This not only affects the display effect but also seriously reduces the user's viewing experience, especially in large-size, high-resolution display panels.

[0004] In order to improve such problems, some excellent image processing techniques are usually improved and applied to such non-uniform compensation to achieve the purpose of improving display effect and user experience, which is called Demura compensation technology. Its implementation process is roughly as follows: detection picture shooting, brightness and chrominance data output, compensation data generation, and compensation effect optimization. Currently, common Demura compensation methods mainly rely on one-time generation of compensation lookup tables and application to brightness and chrominance correction of the entire display panel.

[0005] However, for large-size, high-resolution display panels, the accuracy of brightness and chrominance distribution acquisition is also affected by camera hardware, shooting distance and angle, post-processing, etc., resulting in that single compensation cannot usually achieve ideal results.

[0006] In addition, most existing compensation methods are mainly for specific types of display panels, lack of universality, and cannot provide unified and effective solutions for different display panel types.

[0007] In view of this, the present application proposes a display panel Demura compensation method and system based on three-dimensional lookup table iteration. SUMMARY

[0008] The present application provides a display panel Demura compensation method based on three-dimensional lookup table iteration, which includes four parts: chrominance data photographing, initialization LUT calculation, LUT iterative update, and termination condition judgment.

[0009] Further, the chrominance data photographing part includes: S1.1 photographing picture determination, determining to use an industrial camera to shoot the chrominance data of N pictures of R / G / B three channels according to the Mura performance of the display panel; S1.2 Mura data shooting, after the detection platform based on the industrial camera is built is adapted to the resolution information and pixel arrangement information of the display panel, the display panel is shot according to the display picture determined in advance, three groups of data reflecting the luminance and chrominance information of each display picture are obtained, and the three groups of data are X, Y and Z values in the XYZ color space, wherein the Y component represents the luminance component, and the X and Z components represent the chrominance component; the information of the pixel in the hth row and the wth column on the display panel is recorded as Xh,w, Yh,w and Zh,w under each shot picture. .

[0010] Further, the initialization LUT calculation part includes: S2.1 data reading, the chrominance data obtained by the detection device covers the information of multiple dimensions of luminance and chrominance coordinates, which constitutes the description of the color performance of the display panel, and through the reading of the data, the data is used as the basis for subsequent compensation calculation, and at the same time, the data is subjected to denoising, error correction and standardization processing steps in the reading process, so as to further improve the accuracy and availability of the data; S2.2 LUT calculation, the three-dimensional look-up table refers to the mapping of input color values to output color values through red, green and blue three channels, so as to realize the compensation of color unevenness: in the three-dimensional LUT, each color channel R, G and B is regarded as a dimension, which together constitutes a three-dimensional space, in which each point represents a specific color value, and the LUT defines the mapping relationship of the color values to new color values.

[0011] Further, S2.2 LUT calculation includes: (1) mapping relationship construction represents the RGB value displayed by the pixel point in the hth row and the wth column on the display panel, represents the chrominance information exhibited by the pixel point, and the luminance and chrominance unevenness exhibited by the display panel is embodied by the chrominance information between different pixel points; for the RGB color space and the XYZ color space, when the display panel displays the RGB picture, the XYZ obtained by the detection device has the following description: , wherein, is the XYZ value obtained when the display panel inputs the picture , and have the following conversion relationship: , gamma is the known display gamma value, ideally, all pixels on the display panel should have exactly the same color performance, through the above conversion relationship, all pixel points are selected to achieve uniformity compensation, the first h row, w column pixel of a picture on the display panel has the following conversion relationship: , The compensation input is mapped to the display device, and the following expression is obtained: ; (2) LUT table generation According to the description of the construction of a single pixel point in (1), all pixel points on the display panel are calculated to obtain the lookup table under the current detection picture, and the lookup table description suitable for all detection pictures is as follows: , The construction of the detection picture lookup table is described, and the lookup table of other pictures is calculated by bilinear interpolation and tetrahedral interpolation, Limited to specific display panels or application scenarios, after one lookup table application, the color correction effect may not be ideal, at this time, the lookup table is modified by using LUT iterative update method.

[0012] Further, the LUT iterative update part includes: The first calculated lookup table is represented as Based on the first calculated lookup table, the input value of the subsequent iteration process is determined, and the lookup result of the display panel is represented as: , Next, the same steps as the first LUT calculation are performed in the iteration process, and the calculation result of the lookup table after one iteration is represented as: , Finally, according to the result of the iteration calculation, the update of the LUT is realized, and the update process after one iteration is as follows: , .

[0013] Further, the iteration termination condition part includes: The measurement index of luminance uniformity and chroma uniformity is used as the condition, and n regions are selected as the reference on the display panel, and the calculation method is as follows: , , Wherein represents the calculation result of the luminance uniformity, This represents the brightness of the i-th region out of n regions on the display panel. This represents the average brightness of n regions; The calculation results represent the colorimetric uniformity. , This indicates that the i-th region among the n regions of the display panel is... Chromaticity in a coordinate system , This represents the chromaticity mean of n regions. An error-based termination condition determination method is adopted, and two key termination condition parameters are preset during the execution process, denoted as follows: , ,in The threshold value representing the brightness uniformity index reflects the degree of uniformity that the display panel needs to achieve under certain brightness requirements; while This refers to the chromaticity error threshold, used to measure the uniformity of the display panel in the color dimension. During the iterative calculation process, uniformity is continuously calculated, and the calculation results are compared with the preset termination conditions in real time. When the uniformity calculation result meets the condition... The iteration terminates at that time.

[0014] This invention also provides a Demura compensation system for display panels based on three-dimensional lookup table iteration. The system mainly consists of a data acquisition module, a LUT generation module, an iteration module, and a termination condition judgment module. The data acquisition module includes: determining the detection screen based on the original Mura performance of the display panel; and using an industrial camera to take pictures of different detection screens of the display panel to obtain a data set containing the brightness and chromaticity information of each pixel on the display screen. The LUT generation module includes: detecting and reading the color information of the screen, reading the data that can reflect the brightness and color saturation Mura of the display screen; initializing the LUT calculation, and calculating a three-dimensional lookup table with brightness and color saturation correction function based on the read data by applying the Demura compensation algorithm; The iterative module includes: iterative confirmation, which checks the effect after one compensation. If the requirements are met, the calculation process is exited; if the requirements are not met, the LUT calculation continues iteratively. The iterative LUT calculation follows the process of one LUT calculation, reads the detected data, applies the Demura compensation algorithm again to calculate the updated lookup table, and performs the calculation according to the iterative module process until the calculation process is exited.

[0015] The technical effect of the present application is that although current large-size, high-resolution display panels are continuously optimized in production process, detection technology, compensation algorithm, etc., they are still limited by the diversity of panel defects, the complexity of panel parameters, and the restrictiveness of application scenarios, etc., and one-time Demura compensation often fails to achieve the desired effect. When the one-time calculation effect fails to meet the expectation, iteration is undoubtedly an efficient and commonly used solution strategy. Based on the initial data collected, the compensation effect is modified and improved, which can significantly improve the Demura compensation effect of the display panel; during the iteration, the system detection feedback is also helpful for flexible adjustment of parameters, realizing rapid optimization of the compensation effect; for different display panels, the implementation of the iteration scheme can cleverly integrate the previous data analysis means, which not only can provide strong support for subsequent effect tuning, but also can ensure excellent performance and visual experience in various display scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The figure shows the three-dimensional lookup table iteration flowchart of the present application; Figure 2 The figure shows the display panel detection process of the present application; Figure 3 The figure shows the initial 3D LUT generated by the display panel of the present application; Figure 4 The figure shows the LUT iteration of the display panel of the present application; Figure 5 The figure shows the 3D-LUT iteration Demura compensation preprocessing system diagram of the present application. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0018] Please refer to Figures 1-5 The present application proposes a display panel Demura compensation method and system based on three-dimensional lookup table iteration.

[0019] As Figure 1As shown, first, according to the parameter information of the display panel and the photographing device, new screen adaptation and other work are carried out to ensure the correctness of the device setting and camera debugging, so as to reduce the non-uniformity caused by the device itself as much as possible and ensure the smooth progress of the subsequent steps. Secondly, the detection picture is determined according to the non-uniformity of the display panel, which is directly related to the accuracy of the subsequent compensation data and the improvement of the display effect. Next, the original picture obtained by detection and photographing is processed, including moire elimination, distortion correction and other steps, which is particularly important for large-size display panels, and is the key to accurately identify the brightness and chrominance non-uniformity and the solid foundation for subsequent analysis. Finally, after a series of processing, the brightness and chrominance data used for compensation calculation are obtained, and the compensation lookup table is generated through the Demura compensation scheme.

[0020] However, during the implementation of the entire system, although a series of technical means and scheme measures are taken to reduce errors, the existence of some errors is often difficult to completely avoid. This may result in that the ideal effect cannot be achieved after one compensation. The optimization scheme involving errors caused by system errors, environmental factors and the like is relatively complex and has optimization uncertainty. At this time, algorithm iteration becomes an important means for optimization scheme and performance improvement. Through the repetition of the above detection picture and compensation calculation, the lookup table is iteratively updated, so as to realize more accurate compensation effect, and compared with the one-time Demura flow scheme, the accuracy of the calculation result is greatly improved.

[0021] The present application has the advantages of strong stability (through iterative optimization of the lookup table, the compensation effect can be kept relatively consistent under different environments and conditions), wide applicability (not limited to specific display panels, the iterative parameters can be flexibly adjusted to quickly respond to the specific needs of different products), high implementation efficiency (based on the existing flow scheme, no additional auxiliary operation is introduced, and the waste of time and resources is avoided) and the like.

[0022] The present application provides a display panel Demura compensation method based on three-dimensional lookup table iteration, which includes chrominance data photographing, initialization LUT calculation, LUT iterative update and termination condition judgment.

[0023] The chrominance data photographing part includes: S1.1 photographing picture determination, according to the Mura performance of the display panel, the chrominance data of N pictures (for example: 99, 136, 186, 255 four pictures) of R / G / B three channels are photographed by using an industrial camera; S1.2 Mura data shooting, after the detection platform based on the industrial camera is built is adapted to the resolution information and the pixel arrangement information of the display panel, the display panel is shot according to the display picture determined in advance, three groups of data of luminance and chrominance information are obtained for each display picture, and the three groups of data are X, Y and Z values in XYZ color space, wherein the Y component represents the luminance component, and the X and Z components represent the chrominance component; the information of the pixel in the hth row and the wth column on the display panel is recorded as .

[0024] The initialization LUT calculation part comprises: S2.1 data reading, in order to realize accurate compensation of the Mura defect on the display panel, the chrominance data obtained by the detection equipment becomes the key to execute the compensation calculation. The chrominance data covers information in multiple dimensions such as luminance and chrominance coordinates, and constitutes a description of the color performance of the display panel. Through reading of the data, they are used as the basis for subsequent compensation calculation, and at the same time, denoising, error correction and standardization processing steps can be performed in the reading process, so as to further improve the accuracy and usability of the data; S2.2 LUT calculation, the three-dimensional look-up table described in the embodiment realizes compensation of color unevenness by mapping the input color value of the red, green and blue three channels to the output color value: in the three-dimensional LUT, each color channel R, G and B is regarded as a dimension, and together constitutes a three-dimensional space, in which each point represents a specific color value, and the LUT defines the mapping relationship of the color value to the new color value.

[0025] S2.2 LUT calculation comprises: (1) mapping relationship construction In one embodiment of the present application, the detection picture and the shooting data of the pixel in the hth row and the wth column on the display panel have the relationship as shown in Figure 2 .

[0026] RGB value displayed by the pixel point in the hth row and the wth column on the display panel is represented by The chrominance information exhibited by the pixel point, the luminance and chrominance unevenness exhibited by the display panel are embodied by the chrominance information between different pixel points; for the RGB color space and the XYZ color space, when the display panel displays the RGB picture, the XYZ obtained by the detection equipment has the following description: , Wherein, is the XYZ value obtained when the display panel inputs the picture , and ​ has the following conversion relationship (for example, 8-bit gray scale, gamma is the known display gamma value): , Ideally, all pixel points on the display panel should have completely consistent color performance, and all pixel points are selected by the above conversion relationship to achieve uniformity compensation. The hth row and wth column pixel of a certain picture on the display panel has the following conversion relationship: , The compensation input is mapped to the display device, and the following expression is obtained: ; (2) LUT table generation According to the description of the construction of a single pixel point in (1), all pixel points on the display panel are calculated to obtain the lookup table under the current detection picture, and the lookup table description suitable for all detection pictures is as follows: , As described above, the construction of the detection picture lookup table, the lookup table of other pictures is calculated by bilinear interpolation, tetrahedral interpolation and other methods, such as Figure 3 , shows the output results found by the lookup table constructed by a certain display panel at different inputs.

[0027] Limited by specific display panels or application scenarios, after one lookup table application, there may be a situation that the color correction effect is not ideal. At this time, the lookup table is modified by applying the iteration method of the embodiment, which can improve the applicability of the method on the one hand, and can realize the rapid response of effect optimization based on the existing process on the other hand.

[0028] The LUT iterative update part includes: Iterative calculation is a common method for optimization problems, which can flexibly cope with the uneven characteristics exhibited by different types of display panels, and based on the existing steps and parameters, it can directly optimize and improve the actual situation. In order to facilitate subsequent description, the lookup table calculated for the first time is represented as Based on the lookup table calculated for the first time, the input value of the subsequent iteration process is determined, and the lookup result of the display panel can be represented as: , Next, the same steps as the first LUT calculation are performed in the iteration process, and the calculation result of the lookup table after one iteration is represented as: , Finally, according to the result of the iterative calculation, the update of the LUT is realized, and the update process after one iteration is as follows: , .

[0029] The iterative method is ingenious in that it fully utilizes the fast access characteristics of the lookup table, enabling each step in the iteration process to base on the results of the previous step, efficiently and accurately deriving the input for the next step. This not only enhances the smoothness of the entire iteration process, but also ensures that each calculation step closely follows, effectively avoiding error accumulation or computational redundancy that may occur during the calculation process.

[0030] As Figure 4 , the updated lookup table is shown to find the output results at different inputs.

[0031] The iteration termination condition part includes: The iteration termination condition is a key element to control when the iteration process stops, which can ensure that the iterative algorithm converges to the desired solution within a reasonable time, while avoiding unnecessary computational overhead and potential infinite loops. The purpose of this invention is to improve the effect of chromaticity non-uniformity compensation, taking the measurement index of luminance uniformity and chromaticity uniformity as the condition, usually selecting n regions on the display panel as reference (usually 35), the calculation method is as follows: , , Where represents the calculation result of luminance uniformity, represents the luminance of the i-th region in the n regions of the display panel, represents the average luminance of the n regions; represents the calculation result of chromaticity uniformity, , represents the chromaticity of the i-th region in the n regions of the display panel in the coordinate system, , represents the average chromaticity of the n regions, The invention adopts an error-based termination condition judgment method, which can more accurately and efficiently control the iteration process, ensuring that the algorithm stops in time when the expected error range is reached, avoiding unnecessary waste of computing resources. Specifically, two key termination condition parameters are preset during the method execution process, denoted as , , usually, set to 95%, set to 0.003. Where The threshold value representing the brightness uniformity index reflects the degree of uniformity that the display panel needs to achieve under certain brightness requirements; while This refers to the chromaticity error threshold, used to measure the uniformity of the display panel in the color dimension. During the iterative calculation process, uniformity is continuously calculated, and the calculation results are compared with the preset termination conditions in real time. When the uniformity calculation result meets the condition... The iteration terminates at that time.

[0032] This invention also provides a display panel Demura compensation system based on three-dimensional lookup table iteration, such as... Figure 5 The system shown mainly consists of a data acquisition module, a LUT generation module, an iteration module, and a termination condition judgment module. Industrial camera colorimetric data acquisition unit: detects colorimetric non-uniformity data of display panels.

[0033] Initial LUT calculation unit: Based on the collected chromaticity data, calculate the LUT and perform uniformity condition judgment.

[0034] LUT update computation unit: Based on the result of a single LUT computation, perform LUT iterative computation.

[0035] Iteration Termination Judgment Unit: Set iteration termination conditions according to actual application conditions to avoid unnecessary computational overhead.

[0036] In summary, this invention provides a display panel Demura compensation method and system based on a three-dimensional lookup table iteration. Based on chromaticity data acquired by an industrial camera, the method optimizes and accelerates the iterative process by using a lookup table to obtain the next input value from the initial calculation result. Simultaneously, by specifying reasonable iteration termination conditions according to the actual application scenario, the accuracy and reliability of the calculation results are guaranteed. Especially in application scenarios involving large-size, high-resolution display panels with diverse panel defects and complex panel parameters, a single Demura compensation often fails to achieve the desired effect. Through the implementation of the iterative method, previous data can be cleverly integrated and adaptively adjusted. This not only provides strong support for subsequent effect optimization but also ensures stable performance in various display scenarios. Furthermore, this method allows for more flexible responses to user needs and market changes, thereby improving overall user satisfaction and product competitiveness.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is limited by the appended claims and their equivalents.

Claims

1. A Demura compensation method for display panels based on three-dimensional lookup table iteration, characterized in that: It consists of four parts: capturing colorimetric data, initializing LUT calculation, LUT iterative update, and determining termination conditions.

2. The display panel Demura compensation method based on three-dimensional lookup table iteration according to claim 1, characterized in that, The colorimetric data capture portion includes: S1.1 The image to be captured is determined based on the Mura performance of the display panel, which determines the chromaticity data of N images with three channels (R / G / B) captured by an industrial camera. S1.2 Mura data capture: An inspection platform built on an industrial camera, after adapting to the new screen based on the display panel's resolution and pixel arrangement information, captures images of pre-determined display scenes. Each scene yields three sets of data representing brightness and chromaticity information. These three sets of data are the X, Y, and Z values ​​in the XYZ color space, where the Y component represents the brightness component, and the X and Z components represent the chromaticity component. The information of the h-th row and w-th column pixel on the display screen is also captured. The data from each captured scene are recorded as follows: .

3. The display panel Demura compensation method based on three-dimensional lookup table iteration according to claim 1, characterized in that, The initialization of LUT computation includes: S2.1 Data reading: The chromaticity data acquired by the detection device covers multiple dimensions of information, including brightness and chromaticity coordinates, which constitute a description of the color performance of the display panel. By reading this data, it is used as the basis for subsequent compensation calculations. At the same time, noise reduction, error correction, and standardization processing steps are performed during the reading process to further improve the accuracy and usability of the data. S2.2 LUT calculation, three-dimensional lookup table refers to the mapping of input color values ​​to output color values ​​through the three channels of red, green and blue, thereby realizing the compensation of color unevenness: In the three-dimensional LUT, each color channel R, G, B is regarded as a dimension, which together constitute a three-dimensional space. In this space, each point represents a specific color value, and the LUT defines the mapping relationship between these color values ​​and new color values.

4. The display panel Demura compensation method based on three-dimensional lookup table iteration according to claim 3, characterized in that, S2.2 LUT calculation includes: (1) Construction of mapping relationship This represents the RGB value displayed for the pixel in the h-th row and w-th column on the display panel. This represents the chromaticity information displayed by the pixel. The unevenness in brightness and chromaticity exhibited by the display panel itself is reflected through the chromaticity information between different pixels. For the RGB and XYZ color spaces, when the display panel displays an RGB image, it has the following description compared to the XYZ image obtained by the detection device: ， in, Input screen to display panel The XYZ values ​​obtained at each time point, and It has the following transformation relationship: ， Given a known gamma value for the display, ideally, all pixels on the display panel should have completely consistent color reproduction. Through the aforementioned conversion relationship, a uniform target value is selected for all pixels to achieve uniformity compensation. The pixels in the h-th row and w-th column of a given image on the display panel have the following conversion relationship: ， The compensated input mapped to the display device can be expressed as follows: ； (2) LUT table generation Based on the construction description of a single pixel in (1), calculations are performed on all pixels on the display panel to obtain the lookup table for the current detection screen. The lookup table applicable to all detection screens is described as follows: ， The construction of the lookup table for the detected image is described. The lookup tables for other images are calculated using bilinear interpolation and tetrahedral interpolation. Due to limitations of specific display panels or application scenarios, color correction results may be unsatisfactory after applying a lookup table once. In such cases, the lookup table can be corrected by using an iterative update method of LUT.

5. The display panel Demura compensation method based on three-dimensional lookup table iteration according to claim 1, characterized in that, The LUT iteration update part includes: The lookup table obtained from the initial calculation is represented as follows: Based on the lookup table calculated initially, the input values ​​for subsequent iterations are determined, and the lookup results displayed on the panel are shown as follows: ， Next, the iterative process is performed following the same steps as the first LUT calculation. The result of the lookup table calculation after one iteration is represented as follows: ， Finally, based on the results of the iterative calculation, the LUT is updated. The update process for one iteration is as follows: ， 。 6. The display panel Demura compensation method based on three-dimensional lookup table iteration according to claim 1, characterized in that, The iteration termination condition includes: Using brightness uniformity and color uniformity as metrics, and randomly selecting n areas on the display panel as references, the calculation method is as follows: , , in The calculation results represent the uniformity of brightness. This represents the brightness of the i-th region out of n regions on the display panel. This represents the average brightness of n regions; The calculation results represent the colorimetric uniformity. , This indicates that the i-th region among the n regions of the display panel is... Chromaticity in a coordinate system , This represents the chromaticity mean of n regions. An error-based termination condition determination method is adopted, and two key termination condition parameters are preset during the execution process, denoted as follows: , ,in The threshold value representing the brightness uniformity index reflects the degree of uniformity that the display panel needs to achieve under certain brightness requirements; while This refers to the chromaticity error threshold, used to measure the uniformity of the display panel in the color dimension. During the iterative calculation process, uniformity is continuously calculated, and the calculation results are compared with the preset termination conditions in real time. When the uniformity calculation result meets the condition... The iteration terminates at that time.

7. A system constructed using the Demura compensation method for display panels based on three-dimensional lookup table iteration as described in any one of claims 1-6, characterized in that, The system mainly consists of a data acquisition module, a LUT generation module, an iteration module, and a termination condition judgment module. The data acquisition module includes: determining the detection screen based on the original Mura performance of the display panel; and using an industrial camera to take pictures of different detection screens of the display panel to obtain a data set containing the brightness and chromaticity information of each pixel on the display screen. The LUT generation module includes: detecting and reading the color information of the screen, reading the data that can reflect the brightness and color saturation Mura of the display screen; initializing the LUT calculation, and calculating a three-dimensional lookup table with brightness and color saturation correction function based on the read data by applying the Demura compensation algorithm; The iterative module includes: iterative confirmation, which checks the effect after one compensation. If the requirements are met, the calculation process is exited; if the requirements are not met, the LUT calculation continues iteratively. The iterative LUT calculation follows the process of one LUT calculation, reads the detected data, applies the Demura compensation algorithm again to calculate the updated lookup table, and performs the calculation according to the iterative module process until the calculation process is exited.

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