A display screen brightness compensation method, device, system and storage medium

Abstract

The application discloses a display screen brightness compensation method, device, system and storage medium, which are used for realizing high-precision screen calibration and image registration, and comprise the following steps: acquiring feature images of a to-be-tested screen under different gray scales, extracting a coordinate corresponding relationship between a standard screen and the to-be-tested screen based on the feature images; generating a homography matrix according to the coordinate corresponding relationship, wherein the homography matrix is used for describing a mapping relationship between a standard screen coordinate system and a to-be-tested screen coordinate system; inputting standard sub-pixel position data in a reference coordinate library into the homography matrix, and calculating actual sub-pixel positions of the to-be-tested screen, wherein the reference coordinate library comprises position coordinates of the standard sub-pixels in the standard coordinate system and relative geometric relationships thereof; collecting brightness data of the to-be-tested screen under different gray scales according to the actual sub-pixel positions, and performing brightness compensation on the to-be-tested screen based on the brightness data.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the field of display screen detection, and in particular to a display screen brightness compensation method, device, system and storage medium. BACKGROUND

[0002] With the update iteration of electronic products, the use of display screens is more and more frequent, and consumers have higher requirements for product quality. In the field of display screen production, the brightness uniformity and accuracy of the display screen directly determine the visual effect of the display device, and is one of the core indicators affecting user experience. For mobile phones, televisions, computer monitors and other types of display devices, uneven picture brightness will cause image distortion, color shift, and even visual fatigue in severe cases, reducing product market competitiveness. Since the sub-pixel is the smallest light-emitting unit that constitutes the display picture, its positioning accuracy directly affects the accuracy of brightness compensation, so accurate positioning of the sub-pixel is a basic technology for achieving accurate brightness compensation.

[0003] At present, the traditional display panel brightness compensation method generally adopts a screen-by-screen positioning strategy, that is, the sub-pixel positioning of the RGB / W positioning picture of each display screen needs to be performed. In the specific implementation process, first, a high-precision image acquisition device such as an industrial camera is used to capture the RGB / W positioning picture of each screen. Since the coordinated light emission of red, green, and blue three primary colors and white sub-pixels determines the final display color and brightness, a complex image processing algorithm is needed to identify and calculate the coordinates of the sub-pixels one by one in the positioning picture to determine the actual position of the sub-pixel, and then perform brightness compensation.

[0004] Although the traditional brightness compensation method can ensure a certain accuracy, it needs to perform repeated sub-pixel positioning operations on each screen, which not only consumes a lot of time and labor cost, reduces production efficiency, but also increases the complexity and uncertainty of the production process, which is not conducive to large-scale production. With the growing demand for display screens and the increasing demand for production efficiency, there is an urgent need for a display screen brightness compensation scheme that can simplify the production process and improve production efficiency. SUMMARY

[0005] The present application discloses a display screen brightness compensation method, device, system and storage medium, which is used to realize high-precision screen calibration and image registration.

[0006] The first aspect of the present application discloses a display screen brightness compensation method, comprising:

[0007] Obtaining feature images of the to-be-tested screen under different gray scales, and extracting the coordinate correspondence relationship between the standard screen and the to-be-tested screen based on the feature images;

[0008] generate a homography matrix according to the coordinate correspondence relationship, the homography matrix being used to describe a mapping relationship between the standard screen coordinate system and the to-be-tested screen coordinate system;

[0009] input standard sub-pixel position data in a reference coordinate library into the homography matrix, and calculate actual sub-pixel positions of the to-be-tested screen, the reference coordinate library containing position coordinates of the standard sub-pixel in the standard coordinate system and relative geometric relationships thereof;

[0010] collect luminance data of the to-be-tested screen at different gray scales according to the actual sub-pixel positions, and perform luminance compensation on the to-be-tested screen based on the luminance data.

[0011] Optionally, the generating of the homography matrix according to the coordinate correspondence relationship comprises:

[0012] extracting four corner point coordinates of the feature image of the to-be-tested screen at different gray scales;

[0013] generating the homography matrix based on a correspondence relationship between the four corner point coordinates of the standard screen and the four corner point coordinates of the to-be-tested screen.

[0014] Optionally, the generating of the homography matrix comprises:

[0015] constructing a linear equation set based on at least four non-collinear corner point coordinates of the standard screen and the to-be-tested screen;

[0016] obtaining an optimal parameter set through iterative calculation by using a RANSAC algorithm;

[0017] setting an inlier threshold to eliminate abnormal matching points in the optimal parameter set, obtaining matrix parameters of the homography matrix, and generating the homography matrix.

[0018] Optionally, a formula for mapping the standard sub-pixel position to the to-be-tested screen through the homography matrix is:

[0019]

[0020] wherein h11, h12, …, h33 are matrix parameters solved by a least square method or a RANSAC algorithm, is a coordinate position of the standard screen, is a coordinate position of the to-be-tested screen.

[0021] Optionally, the inputting of the standard sub-pixel position data in the reference coordinate library into the homography matrix to calculate the actual sub-pixel positions of the to-be-tested screen comprises:

[0022] performing homogeneous coordinate conversion on the standard sub-pixel position data to expand two-dimensional coordinates into three-dimensional homogeneous coordinate form;

[0023] linearly transforming standard sub-pixel position data in three-dimensional homogeneous coordinate form by the homography matrix;

[0024] normalizing the transformed coordinates to obtain two-dimensional actual sub-pixel position coordinates of the to-be-tested screen.

[0025] Optionally, the formula for normalizing the transformed coordinates to obtain two-dimensional actual sub-pixel position coordinates of the to-be-tested screen is as follows:

[0026]

[0027] Similarly, the coordinate positions of sub-pixels of the to-be-tested screen and are calculated by the same formula:

[0028]

[0029]

[0030] wherein h11, h12, …, h33 are matrix parameters of the homography matrix, , , are coordinate positions of different colors of the standard screen, , , are coordinate positions of different colors of the to-be-tested screen.

[0031] Optionally, before inputting the standard sub-pixel position data in the reference coordinate library into the homography matrix, the method further comprises:

[0032] calculating an error between the coordinates of the standard screen sub-pixels after the homography matrix transformation and the actual coordinates of the to-be-tested screen, and recalibrating the homography matrix when the error exceeds a preset threshold.

[0033] The second aspect of the present application provides a display screen brightness compensation device, comprising:

[0034] an acquisition unit configured to acquire feature images of a to-be-tested screen under different gray scales, and extract a coordinate correspondence relationship between a standard screen and the to-be-tested screen based on the feature images;

[0035] a generation unit configured to generate a homography matrix according to the coordinate correspondence relationship, the homography matrix being used to describe a mapping relationship between a standard screen coordinate system and a to-be-tested screen coordinate system;

[0036] a calculation unit configured to input standard sub-pixel position data in a reference coordinate library into the homography matrix, and calculate actual sub-pixel positions of the to-be-tested screen, the reference coordinate library containing position coordinates of the standard sub-pixels under a standard coordinate system and relative geometric relationships thereof.

[0037] a compensation unit configured to collect luminance data of the to-be-tested screen under different gray scales according to the actual sub-pixel positions, and perform luminance compensation on the to-be-tested screen based on the luminance data.

[0038] The third aspect of the present application provides a display screen luminance compensation system, comprising:

[0039] a processor, a memory, an input / output unit and a bus;

[0040] The processor is connected with the memory, the input / output unit and the bus;

[0041] The memory stores a program, and the processor invokes the program to execute the method of the first aspect and any optional method of the first aspect.

[0042] The fourth aspect of the present application provides a computer readable storage medium, and the computer readable storage medium stores a program, and the program is executed on a computer to execute the method of the first aspect and any optional method of the first aspect.

[0043] From the above technical solutions, it can be seen that the embodiments of the present application have the following advantages:

[0044] The present application first performs high-precision sub-pixel positioning on a standard screen, constructs a reference coordinate library containing the position coordinates of standard sub-pixels in a standard coordinate system and the relative geometric relationship thereof, then acquires feature images of a to-be-tested screen under different gray scales, quickly extracts the coordinate correspondence relationship of the standard screen and the to-be-tested screen through edge detection, and further generates a homography matrix. Subsequently, the standard sub-pixel position data in the reference coordinate library is input into the homography matrix, and the actual sub-pixel positions of the to-be-tested screen can be calculated without tedious sub-pixel positioning calculation for each to-be-tested screen. The time and labor cost of industrial camera acquisition and complex processing are reduced, the production process is simplified, the production efficiency is effectively improved, the production complexity and uncertainty are reduced, the production line cycle is shortened, and the present application is suitable for large-scale production scenarios.

[0045] Secondly, by constructing an accurate reference coordinate library and a scientific mapping mechanism, the positioning accuracy is improved. On the one hand, the reference coordinate library records the position coordinates of the standard sub-pixels in the standard coordinate system and the relative geometric relationship thereof in detail, providing a high-precision reference datum for subsequent to-be-tested screen positioning; on the other hand, the coordinate correspondence relationship of the standard screen and the to-be-tested screen is extracted using feature images under different gray scales, and a homography matrix is generated, which can accurately describe the mapping relationship between the two coordinate systems. When calculating the actual sub-pixel positions of the to-be-tested screen, based on the accurate reference coordinate library data and the reliable homography matrix mapping, factors such as substrate deformation and process errors that may exist in the production process of the display panel can be fully considered, the sub-pixel positions can be accurately determined, the positioning accuracy is improved, and the complexity of the sub-pixel positioning algorithm is reduced. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This is a schematic diagram of an embodiment of the display screen brightness compensation method of this application;

[0048] Figure 2 This is a schematic diagram of an embodiment of the method for generating a homography matrix based on coordinate correspondence in this application;

[0049] Figure 3 This is a schematic diagram of an embodiment of the method for calculating and generating the homography matrix in this application;

[0050] Figure 4 This is a schematic diagram of an embodiment of the method for calculating the actual sub-pixel position of the screen under test in this application;

[0051] Figure 5 This is a schematic diagram of an embodiment of the method for determining whether to recalibrate the homography matrix in this application;

[0052] Figure 6 This is a schematic diagram of one embodiment of the display screen brightness compensation device of this application;

[0053] Figure 7 This is a schematic diagram of an embodiment of the display screen brightness compensation system of this application. Detailed Implementation

[0054] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0055] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0056] It should also be understood that the term “and / or” as used herein refers to any one of the associated listed items, optionally, as well as all possible combinations of the associated listed items. It should also be understood that, in the description and claims of the application, relative terms such as “first”, “second”, “third”, etc., are used to distinguish one element from another, and are not necessarily used to describe a relative importance of the elements.

[0057] As used in the description of the application and the appended claims, the term “if’ can be interpreted to mean “when” or “upon” or “in response to determining” or “in response to detecting” depending on the context. Similarly, the phrase “if it is determined” or “if [a described condition or event] is detected” can be interpreted to mean “upon determining” or “in response to determining” or “upon [the described condition or event] being detected” or “in response to [the described condition or event] being detected”, depending on the context.

[0058] In addition, in the description of the application and the appended claims, the terms “first”, “second”, “third”, etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0059] In the description of the application, the reference “one embodiment” or “some embodiments” and the like means that the specific features, structures or characteristics described in connection with the embodiment are included in one or more embodiments of the application. Therefore, the statements “in one embodiment”, “in some embodiments”, “in other some embodiments”, “in further some embodiments” and the like appearing in different places in the specification are not necessarily all referring to the same embodiment, but mean “one or more but not all embodiments”, unless otherwise specifically emphasized. The terms “include”, “contain”, “have” and their variants mean “include but not limited to”, unless otherwise specifically emphasized.

[0060] Based on this, the application discloses a display screen brightness compensation method, device, system and storage medium, which is used to realize high-precision screen calibration and image registration.

[0061] The technical solutions in the application will be described clearly and completely in the description of the embodiments of the application combined with the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0062] The method of the application can be applied to a server, a device, a terminal or other devices with logical processing capability, and the application is not limited thereto. For the convenience of description, the following will be described taking the system as an example.

[0063] Please refer to Figure 1An embodiment of a display screen brightness compensation method is provided, comprising:

[0064] 101. Obtain feature images of the to-be-tested screen under different gray scales, and extract the coordinate correspondence between the standard screen and the to-be-tested screen based on the feature images;

[0065] 102. Generate a homography matrix based on the coordinate correspondence, and the homography matrix is used to describe the mapping relationship between the standard screen coordinate system and the to-be-tested screen coordinate system;

[0066] 103. Input the standard sub-pixel position data in the reference coordinate library into the homography matrix, and calculate the actual sub-pixel position of the to-be-tested screen, wherein the reference coordinate library contains the position coordinates of the standard sub-pixel under the standard coordinate system and the relative geometric relationship thereof;

[0067] 104. Collect the brightness data of the to-be-tested screen under different gray scales according to the actual sub-pixel position, and perform brightness compensation on the to-be-tested screen based on the brightness data.

[0068] In step 101, first, the to-be-tested screen is tested under multiple gray scales to obtain feature images thereof under different gray scales. These feature images contain the display characteristics of the to-be-tested screen under different driving conditions. Through an image processing algorithm, the geometric feature points of the to-be-tested screen are extracted from the feature images, and are matched with the corresponding feature points of the standard screen to establish the coordinate correspondence therebetween. Specifically, the to-be-tested screen is sequentially input with 0 gray scale, 128 gray scale and 255 gray scale signals, and three feature images are vertically photographed by using an industrial camera. The all-black image is subjected to Gaussian blur denoising, the all-white image is subjected to histogram equalization to enhance the edge contrast, and the effective display area is cropped. Then, the preprocessed image is subjected to Canny edge detection, the low threshold value is set to 50, the high threshold value is set to 150, and the rectangular edge contour of the screen body is extracted. The Douglas-Peucker algorithm is used to approximate the contour, the coordinates of the four corners are determined, and the coordinate accuracy is improved to the sub-pixel level through cubic spline interpolation. The BRIEF feature descriptor is used to match the same-named corner points in different gray scale images, the Hamming distance is calculated to screen the matching pairs, the coordinates of the same corner point under different gray scales are averaged, the geometric relationship of the four corner points is checked, the edge length error and the internal angle are calculated, and the matching points with errors are removed. Finally, the coordinate correspondence table of the standard screen and the to-be-tested screen is established.

[0069] Based on the coordinate correspondence obtained in step 101, the homography matrix is calculated by using an optimization algorithm such as the least square method in step 102. The 3×3 homography matrix completely describes the projection transformation relationship between the standard screen coordinate system and the to-be-tested screen coordinate system, including rotation, translation, scaling and perspective deformation and other geometric transformations.

[0070] In step 103, the standard sub-pixel position data in the pre-established reference coordinate library is input into the homography matrix, and the corresponding actual sub-pixel position on the to-be-measured screen is obtained through matrix operation. The reference coordinate library contains the accurate coordinates of each sub-pixel on the standard screen and the relative geometric relationship thereof, and these data are obtained in advance through high-precision measurement equipment.

[0071] In step 104, according to the calculated actual sub-pixel position, the luminance data of the to-be-measured screen under different gray scales are collected using a high-precision luminometer. These luminance data are compared with the reference luminance of the standard screen, and the luminance compensation value of each sub-pixel is calculated to generate a luminance compensation lookup table. The luminance compensation process includes: measuring the actual luminance under multiple gray scales (such as 0-255), establishing a luminance-gray scale response curve, calculating a compensation coefficient to match the response curve with the standard curve, and writing the compensation coefficient into the display screen driving chip.

[0072] In this embodiment, first, a high-precision sub-pixel positioning is performed on the standard screen to construct a reference coordinate library containing the position coordinates of the standard sub-pixels in the standard coordinate system and the relative geometric relationship thereof, and then the feature images of the to-be-measured screen under different gray scales are obtained. The coordinate correspondence relationship between the standard screen and the to-be-measured screen is quickly extracted through edge detection, and then a homography matrix is generated. Subsequently, the standard sub-pixel position data in the reference coordinate library are input into the homography matrix, and the actual sub-pixel position of the to-be-measured screen can be calculated without tedious sub-pixel positioning calculation for each to-be-measured screen. The time and labor cost of industrial camera acquisition and complex processing are reduced, the production process is simplified, the production efficiency is effectively improved, the production complexity and uncertainty are reduced, the production line cycle is shortened, and the method is suitable for large-scale production scenarios.

[0073] Secondly, by constructing an accurate reference coordinate library and a scientific mapping mechanism, the positioning accuracy is improved. On the one hand, the reference coordinate library records the position coordinates of the standard sub-pixels in the standard coordinate system and the relative geometric relationship thereof in detail, providing a high-precision reference for subsequent to-be-measured screen positioning; on the other hand, the coordinate correspondence relationship between the standard screen and the to-be-measured screen is extracted using the feature images under different gray scales, and a homography matrix is generated, which can accurately describe the mapping relationship between the two coordinate systems. When calculating the actual sub-pixel position of the to-be-measured screen, based on the accurate reference coordinate library data and the reliable homography matrix mapping, the possible substrate deformation, process error and other factors in the production process of the display panel can be fully considered, the sub-pixel position can be accurately determined, the positioning accuracy is improved, and the complexity of the sub-pixel positioning algorithm is reduced.

[0074] Please refer to Figure 2 An embodiment of a method for generating a homography matrix according to a coordinate correspondence relationship is provided in the present application, which comprises:

[0075] 201、extracting four corner point coordinates of feature images of the to-be-measured screen under different gray scales;

[0076] 202、Based on the corresponding relationship between the four corner point coordinates of the standard screen and the four corner point coordinates of the to-be-measured screen, a homography matrix is calculated and generated.

[0077] In step 201, Canny edge detection or Hough transformation is performed on the gray scale image taken of the to-be-measured screen to extract the four corner point coordinates of the feature image of the to-be-measured screen at different gray scales 、 、 、 .

[0078] In step 202, a homography matrix describing the geometric transformation between the two is calculated based on the four intersection point coordinates. Specifically, a one-to-one correspondence is established between the corner point coordinates of the to-be-measured screen and the pre-measured corner point coordinates of the standard screen. The standard screen corner point coordinates are obtained by a high-precision measuring device and stored in a reference database. The homography matrix is calculated by the following formula:

[0079]

[0080] wherein, (1≤i≤4) is a set of four corner point row coordinates corresponding to the standard screen area, (1≤j≤4) is a set of four corner point column coordinates corresponding to the standard screen area; (1≤i≤4) is a set of four corner point positioning row coordinates of the to-be-measured screen screen area, (1≤j≤4) is a set of four corner point positioning column coordinates of the to-be-measured screen screen area; Matrix is a 3*3 size homography matrix, specifically: .

[0081] In this embodiment, through accurate four corner point matching and homography matrix calculation, the following technical advantages are achieved:

[0082] High-precision geometric correction: can accurately compensate for translation, rotation, scaling and perspective distortion of the to-be-measured screen;

[0083] High computational efficiency: only four feature points are needed to complete the calculation, suitable for rapid detection on production lines;

[0084] Strong robustness: not sensitive to slight changes in light and image noise;

[0085] Good compatibility: suitable for various types of display screens, including LCD, OLED, etc.

[0086] Please refer to Figure 3 , an embodiment of a method for calculating and generating a homography matrix is provided, comprising:

[0087] 301. Construct a linear equation system based on the at least four non-collinear corner point coordinates of the standard screen and the screen to be measured;

[0088] 302. Obtain the optimal parameter set by iterative calculation using the RANSAC algorithm;

[0089] 303. Set an inlier threshold to remove abnormal matching points in the optimal parameter set, obtain the matrix parameters of the homography matrix, and generate the homography matrix.

[0090] In step 301, at least four non-collinear corner point coordinates of the standard screen and the screen to be measured are first obtained. Corner points are points in an image with distinct features, usually located at the intersection of edges. In the screen calibration scenario, these corner points can be the four vertices of the screen or other known feature points. The non-collinear requirement is to ensure that there is a unique solution to the problem, as three collinear points cannot determine a plane. After obtaining these corner point coordinates, a linear equation system is constructed to describe the mapping relationship between the point coordinates.

[0091] In step 302, the RANSAC (Random Sample Consensus) algorithm is used to estimate the homography matrix, which has strong robustness to outliers. Specifically, a small number of sample points are randomly selected to estimate the model parameters, then the support degree of other points for the model is evaluated, and finally the model with the most support is selected as the optimal model. The specific steps are as follows:

[0092] Randomly select 4 pairs of non-collinear corner points from all matching point pairs;

[0093] Solve the linear equation system using the 4 pairs of corner points to obtain a homography matrix estimate;

[0094] Calculate the projection error of all point pairs under the homography matrix;

[0095] Mark the point pairs with errors less than a certain threshold as inliers;

[0096] If the number of inliers exceeds a predetermined minimum value, re-estimate the homography matrix using all inliers;

[0097] Repeat the above process several times, and select the model with the most inliers as the final result.

[0098] Based on step 302, a homography matrix estimate with the most inlier support is obtained after the RANSAC algorithm iteration ends. However, there may still be some points with large errors in these inliers, so further screening is needed.

[0099] In step 303, by setting a suitable inlier threshold, points with projection errors exceeding the threshold are removed again. The selection of this threshold is usually based on the specific application scenario and data characteristics, and needs to be balanced between accuracy and robustness.

[0100] After the outliers are removed, the remaining high-quality inliers are used to estimate the homography matrix again to obtain the final matrix parameters. The homography matrix can accurately describe the geometric transformation relationship between the standard screen and the to-be-tested screen.

[0101] In the embodiment, a linear equation set is constructed by at least four non-collinear corner points to ensure a unique solution of the homography matrix parameters, avoid the solution degeneration problem caused by collinear points, and improve the mapping accuracy. Iterative removal of abnormal matching points effectively resists corner detection errors (such as edge blur and noise interference) and false matching, so that the homography matrix is closer to the real geometric transformation. The random sampling strategy of RANSAC reduces the dependence on the full amount of data, quickly converges to the optimal solution through a limited number of iterations, converts the homography matrix solution into a linear equation set problem, avoids the complex iterative process of nonlinear optimization, and reduces the computational complexity.

[0102] Referring to Figure 4 , the application provides an embodiment of a method for calculating actual sub-pixel positions of a to-be-tested screen, which comprises the following steps:

[0103] 401. Homogeneous coordinate conversion is performed on standard sub-pixel position data to expand two-dimensional coordinates into three-dimensional homogeneous coordinate form;

[0104] 402. Linear transformation is performed on the three-dimensional homogeneous coordinate form of the standard sub-pixel position data by using a homography matrix;

[0105] 403. Normalization processing is performed on the transformed coordinates to obtain two-dimensional actual sub-pixel position coordinates of the to-be-tested screen.

[0106] The matrix multiplication is unfolded and the homogeneous coordinates are normalized. The formula for mapping the offline standard sub-pixel position to the online to-be-tested screen by using the homography matrix Matrix is as follows:

[0107]

[0108] where h11, h12, …, h33 are matrix parameters solved by the least square method or the RANSAC algorithm, is the coordinate position of the standard screen, is the coordinate position of the to-be-tested screen.

[0109] Suppose the coordinate position of the offline standard sub-pixel Rstd is , then the coordinate position of the to-be-tested screen sub-pixel is as follows:

[0110]

[0111] Similarly, the coordinate positions of the to-be-tested screen sub-pixels and The coordinate positions of the standard screen are calculated by the same formula:

[0112]

[0113]

[0114] where h11, h12, …, h33 are the matrix parameters of the homography matrix, are the coordinate positions of different colors of the standard screen, are the coordinate positions of different colors of the screen to be measured.

[0115] In this embodiment, the normalization process ensures the consistency and interpretability of the coordinates, converting the representation in the homogeneous coordinate system into actual physical coordinates. The normalization process also avoids the singularity problem of the denominator being zero in the homogeneous coordinates, ensuring the reliability of the algorithm in various scenarios. Through the homography matrix and the normalization process, accurate coordinate mapping from the standard screen to the screen to be measured is achieved.

[0116] Referring to Figure 5 , an embodiment of a method for determining whether to recalibrate the homography matrix is provided, comprising:

[0117] 501. Calculate the error between the coordinates of the standard screen sub-pixels after homography matrix transformation and the actual coordinates of the screen to be measured. When the error exceeds the preset threshold, recalibrate the homography matrix.

[0118] By monitoring the coordinate mapping error between the standard screen and the screen to be measured in real time, the recalibration process is automatically triggered when the error exceeds the acceptable range, ensuring that the system maintains a high-precision coordinate mapping relationship for a long time.

[0119] Specifically, different error thresholds are set to trigger the recalibration process:

[0120] Global threshold: Set a fixed error threshold. When the error of any detection point exceeds the threshold, trigger calibration.

[0121] Statistical threshold: Calculate the average error or root mean square error of all detection points. When the statistical error exceeds the threshold, trigger calibration.

[0122] Adaptive threshold: Dynamically adjust the threshold according to the system operating environment, such as appropriately relaxing the threshold in high-temperature environments, or tightening the threshold during precise operations.

[0123] ​​​​When the error is detected to exceed the threshold value, the system automatically starts re-calibration, re-acquires the at least four non-collinear corner point coordinates of the standard screen and the screen to be measured, re-estimates the homographic matrix parameters using the RANSAC algorithm, and generates a new homographic matrix.

[0124] After generating the new homographic matrix, the error level coefficient is generated according to the previous homographic matrix global threshold value, the statistical threshold value and the adaptive threshold value , the formula is as follows:

[0125]

[0126] Among them, , and are the global error, the statistical error and the adaptive error respectively, , and are the global threshold value, the statistical threshold value and the adaptive threshold value respectively, the matrix element adjustment value is calculated according to the two homographic matrices, the formula is as follows:

[0127]

[0128] Among them, M is the number of row elements of the homographic matrix, N is the number of vertical elements of the homographic matrix, is the element value at the coordinate (i, j) in the original homographic matrix, is the element value at the coordinate (i, j) in the corrected homographic matrix.

[0129] Next, the abnormal element adjustment value of the abnormal point position and the corner element adjustment value of the corner point are calculated according to the two homographic matrices, is the kth abnormal element value in the original homographic matrix, is the element value corresponding to the kth abnormal element in the corrected homographic matrix, and T is the number of abnormal point positions. is the s th corner element value in the original homographic matrix, is the element value corresponding to the s th corner element in the corrected homographic matrix, and S is the number of corners.

[0130]

[0131]

[0132] According to the matrix element adjustment value , the abnormal element adjustment value and the corner element adjustment value of the corner point, the balanced adjustment value is generated by analysis and calculation;

[0133]

[0134] When the equalization adjustment value is compared with the error level coefficient , it is determined whether the equalization adjustment value and the error level coefficient are comparable in degree, that is, whether the degree of adjustment and the degree of the original error are adapted, and if not, the equalization adjustment value is used. A new fine adjustment parameter is calculated, and the new homography matrix is adjusted as a whole.

[0135] In this embodiment, by continuously monitoring and dynamically calibrating, the parameter drift caused by factors such as screen aging and temperature change is compensated, and the system is ensured to maintain high precision for a long time. Combined with the noise resistance of the RANSAC algorithm, reliable coordinate mapping can still be maintained when there is environmental interference. Calibration can be completed without manual intervention, and is suitable for unattended equipment.

[0136] Referring to Figure 6 , an embodiment of a device for display screen brightness compensation is provided, comprising:

[0137] The acquisition unit 601 is configured to acquire feature images of the to-be-tested screen under different gray scales, and extract a coordinate correspondence relationship between the standard screen and the to-be-tested screen based on the feature images.

[0138] The generation unit 602 is configured to generate a homography matrix based on the coordinate correspondence relationship, the homography matrix being used to describe a mapping relationship between a standard screen coordinate system and a to-be-tested screen coordinate system.

[0139] Optionally, the generation unit 602 comprises:

[0140] The four corner point coordinates of the feature images of the to-be-tested screen under different gray scales are extracted.

[0141] Based on the correspondence relationship between the four corner point coordinates of the standard screen and the four corner point coordinates of the to-be-tested screen, the homography matrix is calculated and generated.

[0142] Optionally, the generation unit 602 further comprises:

[0143] Based on at least four non-collinear corner point coordinates of the standard screen and the to-be-tested screen, a linear equation set is constructed.

[0144] An optimal parameter set is obtained by iterative calculation using the RANSA algorithm.

[0145] An inlier threshold is set to eliminate abnormal matching points in the optimal parameter set, obtain matrix parameters of the homography matrix, and generate the homography matrix.

[0146] Optionally, it further comprises a calibration unit 603:

[0147] The error between the coordinate of the standard sub-pixel after the homographic matrix transformation and the actual coordinate of the to-be-tested screen is calculated, and when the error exceeds a preset threshold, the homographic matrix is recalibrated.

[0148] The computing unit 604 is configured to input the standard sub-pixel position data in the reference coordinate library into the homographic matrix to obtain the actual sub-pixel position of the to-be-tested screen, wherein the reference coordinate library comprises the position coordinates of the standard sub-pixel in the standard coordinate system and the relative geometric relationship thereof.

[0149] Optionally, the computing unit 604 comprises:

[0150] The standard sub-pixel position data is subjected to homogeneous coordinate conversion to expand the two-dimensional coordinates into three-dimensional homogeneous coordinate form.

[0151] The standard sub-pixel position data in the three-dimensional homogeneous coordinate form is subjected to linear transformation by the homographic matrix.

[0152] The transformed coordinates are subjected to normalization processing to obtain the two-dimensional actual sub-pixel position coordinates of the to-be-tested screen.

[0153] The compensation unit 605 is configured to collect the luminance data of the to-be-tested screen at different gray scales according to the actual sub-pixel position, and perform luminance compensation on the to-be-tested screen based on the luminance data.

[0154] The embodiments are described in detail with reference to Figures 1-5 The embodiments are described in detail with reference to

[0155] Please refer to Figure 7 The application provides a display screen luminance compensation system, comprising:

[0156] The processor 701, the memory 702, the input / output unit 703 and the bus 704.

[0157] The processor 701 is connected with the memory 702, the input / output unit 703 and the bus 704.

[0158] The memory 702 stores a program, and the processor 701 calls the program to execute the method in Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 and Figure 5 .

[0159] The application provides a computer readable storage medium, and the computer readable storage medium stores a program, and the program is executed on a computer to execute the method in Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 and Figure 5 .

[0160] Those skilled in the art can clearly understand that, for the convenience and brevity of the description, the specific working processes of the above-described system, device and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

[0161] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other manners. For example, the described device embodiments are merely schematic, and the division of the units is merely a logical function division, and there can be another division manner in actual implementation, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections can be indirect couplings or communication connections through some interfaces, devices or units, and can be electrical, mechanical or other forms.

[0162] The units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, that is, can be located in one place, or can be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the embodiment scheme.

[0163] In addition, each functional unit in the embodiments of the present application can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0164] When the integrated unit is realized in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on such an understanding, the technical solutions of the present application essentially or the part that makes a contribution to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in the embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, read-only memory), a random access memory (RAM, random access memory), a magnetic disk or an optical disk, and various media that can store program codes.

Claims

1. A method for compensating the brightness of a display screen, characterized in that, include: Acquire feature images of the screen under test at different gray levels, and extract the coordinate correspondence between the standard screen and the screen under test based on the feature images; A homography matrix is ​​generated based on the coordinate correspondence, and the homography matrix is ​​used to describe the mapping relationship between the standard screen coordinate system and the screen coordinate system under test; The standard sub-pixel position data in the reference coordinate library is input into the homography matrix to calculate the actual sub-pixel position of the screen under test. The reference coordinate library contains the position coordinates of the standard sub-pixels in the standard coordinate system and their relative geometric relationships. The brightness data of the screen under test at different gray levels is collected according to the actual sub-pixel positions, and the brightness compensation of the screen under test is performed based on the brightness data. The standard sub-pixel position data from the reference coordinate library is input into the homography matrix to calculate the actual sub-pixel position of the screen under test, including: The standard sub-pixel position data is subjected to homogeneous coordinate transformation to expand the two-dimensional coordinates into a three-dimensional homogeneous coordinate form; The homography matrix is ​​used to perform a linear transformation on the standard sub-pixel position data in three-dimensional homogeneous coordinate form; The transformed coordinates are normalized to obtain the two-dimensional actual sub-pixel position coordinates of the screen under test; The formula for mapping the standard sub-pixel position to the screen under test using the homography matrix is: Where h11, h12, ..., h33 are the matrix parameters of the homography matrix. The coordinates of the standard screen are... The coordinates are the positions of the screen to be tested.

2. The display screen brightness compensation method according to claim 1, characterized in that, The step of generating a homography matrix based on the coordinate correspondence includes: Extract the coordinates of the four corner points of the feature image at different gray levels of the screen under test; Based on the correspondence between the coordinates of the four corner points of the standard screen and the coordinates of the four corner points of the screen under test, a homography matrix is ​​calculated and generated.

3. The display screen brightness compensation method according to claim 2, characterized in that, The calculation of generating the homography matrix includes: Based on the coordinates of at least four non-collinear corner points of the standard screen and the screen under test, a system of linear equations is constructed; The RANSA algorithm is used to obtain the optimal parameter set through iterative calculation; Set an interior point threshold to remove abnormal matching points from the optimal parameter set, obtain the matrix parameters of the homography matrix, and generate the homography matrix.

4. The display screen brightness compensation method according to claim 1, characterized in that, The formula for obtaining the actual two-dimensional sub-pixel position coordinates of the screen under test by normalizing the transformed coordinates is as follows: Similarly, the sub-pixels of the screen under test and The coordinates are calculated using the same formula: Where h11, h12, ..., h33 are the matrix parameters of the homography matrix. , , These represent the coordinate positions of different colors on a standard screen. , , These represent the coordinate positions of different colors on the screen under test.

5. The display screen brightness compensation method according to any one of claims 1 to 4, characterized in that, Before inputting the standard sub-pixel position data from the reference coordinate library into the homography matrix, the method further includes: The error between the coordinates of the standard screen sub-pixels after homography matrix transformation and the actual coordinates of the screen under test is calculated. When the error exceeds a preset threshold, the homography matrix is ​​recalibrated.

6. A display screen brightness compensation device, characterized in that, For performing the method as described in any one of claims 1 to 5, comprising: The acquisition unit is used to acquire feature images of the screen under test at different gray levels, and extract the coordinate correspondence between the standard screen and the screen under test based on the feature images; The generation unit is used to generate a homography matrix based on the coordinate correspondence, wherein the homography matrix is ​​used to describe the mapping relationship between the standard screen coordinate system and the screen coordinate system under test; The calculation unit is used to input the standard sub-pixel position data in the reference coordinate library into the homography matrix and calculate the actual sub-pixel position of the screen under test. The reference coordinate library contains the position coordinates of the standard sub-pixels in the standard coordinate system and their relative geometric relationships. The compensation unit is used to collect brightness data of the screen under test at different gray levels according to the actual sub-pixel positions, and to perform brightness compensation on the screen under test based on the brightness data.

7. A display screen brightness compensation system, characterized in that, include: The processor includes a processor, a memory, an input / output unit, and a bus, wherein the processor is connected to the memory, the input / output unit, and the bus, the memory stores a program, and the processor calls the program to execute the display screen brightness compensation method as described in any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium contains a program that, when executed on a computer, performs the display screen brightness compensation method as described in any one of claims 1 to 5.

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