A sub-pixel level color balance compensation method and system for an OLED display panel based on De-Mura compensation technology

Abstract

The present invention provides a sub-pixel level color balance compensation method and system for an OLED display panel based on De-Mura compensation technology. It mainly includes that a luminance industrial camera first takes pictures of the luminance data of different gray levels of the OLED display panel, synchronously performs a luminance uniformity preprocessing process, and burns the compensation parameters into the DDIC (Display Driver Integrated Circuit). According to the chromaticity uniformity performance after luminance uniformity compensation, it is determined whether chromaticity uniformity compensation is required. If so, the gray level picture to be taken is determined according to the color performance of the OLED panel. Then, a chromaticity industrial camera secondarily takes pictures of the chromaticity data of different gray levels of the OLED display panel, processes the chromaticity data to obtain compensation coefficients, and applies them to the luminance compensation data, thereby obtaining the luminance-chromaticity uniformity compensation parameters; based on the above compensation parameters, the luminance-chromaticity compensation of the OLED display panel is realized.

Description

Technical Field

[0001] The present invention relates to an image compensation algorithm, belonging to the field of image processing, and particularly to a sub-pixel level color equalization compensation method and system for an OLED display panel based on De-Mura compensation technology. Background Art

[0002] In today's flat panel display technology field, especially with the continuous breakthrough of technical problems related to OLED (Organic Light-Emitting Diode) panels and the continuous improvement of the corresponding technology industries, the demand for OLED panels shows a rapid growth trend. OLED panels not only have inherent advantages such as self-luminescence, ultra-thin, power-saving, and bright colors, but also can achieve innovative designs such as full-screen and flexible screens, meeting the diversified needs of modern smart phones. With the popularization of OLED panels in the market, the standards of users and manufacturers for panel performance are also gradually rising. The performance of the panel in terms of brightness and chromaticity uniformity can be directly subjectively felt and has become a key consideration index. In terms of brightness uniformity, many existing compensation schemes can already achieve a uniformity compensation effect that meets industry standards, including but not limited to OFFSET compensation, polynomial fitting compensation, etc. In terms of chromaticity uniformity, the existing compensation schemes mainly rely on the partition adjustment method. On the basis of the aforementioned brightness compensation effect, a mixed color image is taken, and at the same time, the screen is divided into multiple regions. The parameters are calculated according to the taken image to compensate and adjust different regions to improve the chromaticity uniformity performance. However, due to the differences in the response characteristics of different pixels and the different arrangement methods, the adjustment effect may not be ideal and it is difficult to uniformly apply the parameters between different panels. With the popularization of HDR video content and the stringent requirements of new technologies such as AR / VR for display quality, OLED panels with excellent chromaticity uniformity are increasingly in hot demand in the market. Summary of the Invention

[0003] The present invention provides a sub-pixel level color equalization compensation method for an OLED display panel based on De-Mura compensation technology, including:

[0004] Step 1: Start, and a brightness industrial camera takes the first brightness data.

[0005] Step 2: Obtain the brightness data of different gray levels of the three channels R / G / B.

[0006] Step 3: Perform brightness uniformity compensation processing.

[0007] Step 4: Generate brightness uniformity compensation parameters and a burn-in file, and burn them into the display driver integrated circuit.

[0008] Step 5: Determine whether chromaticity uniformity correction is required. If so, the chromaticity industrial camera takes a second shot of chromaticity data, obtains the chromaticity data of different gray levels in the W screen, performs chromaticity uniformity compensation processing, generates chromaticity uniformity compensation coefficients and burn files, and burns them into the display driver integrated circuit; if not, end.

[0009] Further, the luminance data in Step 2 includes:

[0010] The luminance data of a total of 3×5 groups of sub-pixel points corresponding to five gray levels of 32, 64, 128, 192, and 255, and the captured data is used in the De-Mura preprocessing process.

[0011] Further, the process of luminance uniformity compensation in Step 3 is as follows:

[0012] The luminance data obtained in Step 2 is subjected to the following fitting process:

[0013] (i) The basic formula for fitting is shown in Formula (1):

[0014]

[0015] where represents luminance, represents the gray level, is the exponential parameter, is the linear parameter related to luminance. This formula is used to describe the relationship between different gray levels and luminance for subsequent calculation of compensation parameters;

[0016] (ii) The calculation process of the luminance uniformity compensation parameters at the sub-pixel level is shown in Formula (2):

[0017]

[0018] where in and the two parameters are used to describe the target luminance, in and the parameters are used to describe the compensation parameters of the sub-pixels. Based on the input gray level and the parameter relationship, the corresponding output gray level of the sub-pixel is obtained;

[0019] (iii) The above Formula (2) can be expressed in the form of the following Formula (3):

[0020]

[0021] Let , and Formula (3) can then be re-expressed as Formula (4)

[0022]

[0023] and Perform the above calculation process on the R / G / B three sub-pixels respectively, and record the result as 、 , Take as R / G / B.

[0024] Furthermore, the process of chromaticity uniformity compensation in step five is as follows:

[0025] By introducing the uniformity compensation coefficient , correct the original input gray scale to improve the chromaticity uniformity. This process is expressed as formula (5):

[0026]

[0027] For the convenience of derivation, expand formula (5) to obtain formula (6):

[0028]

[0029] Formula (6) is further expressed as formula (7):

[0030]

[0031] In formula (7), is denoted as , and is denoted as , to obtain formula (8):

[0032]

[0033] Combining formula (4) and (8), it can be seen that when the chromaticity correction coefficient is obtained, based on the De-Mura process, by modifying the compensation parameter as the chromaticity uniformity correction function is synchronously realized.

[0034] Furthermore, compress the compensation parameters calculated in step four to generate a burn-in file and burn it into the display driver integrated circuit, and the chromaticity industrial camera takes a second photo of the W screen:

[0035] When the color conditions of different gray scale screens are the same, only one screen needs to be photographed;

[0036] When there are differences in the color conditions of different grayscale images, multiple images are captured. The W image is captured by a chrominance industrial camera, so as to obtain the luminance data of the R / G / B sub-pixels of each pixel under the W image. According to the R / G / B luminance data ratio coefficients of the selected target positions, the average value of the captured luminance data in this area is denoted as 、 , and the ratio coefficients of the actual sub-pixels are calculated from the photographed data:

[0037] Denote the sub-pixel captured luminance data of the th pixel as 、 , then the compensation adjustment coefficient of this sub-pixel is / 、 / 、 / , and the compensation coefficient at this position is obtained .

[0038] Furthermore, when capturing a single data, based on the compensation coefficient and the compensation parameter , calculate the R / G / B color uniformity compensation parameter according to the formula ;

[0039] When capturing multiple grayscales, apply the compensation coefficients calculated under different grayscales to the R / G / B captured luminance data of the corresponding grayscales of the luminance industrial camera, and fit and calculate new and , where are the multiple grayscales captured;

[0040] Compress the finally calculated OLED panel full sub-pixel compensation parameters and to generate a burn-in file and burn it into the display driver integrated circuit.

[0041] The present invention also provides a sub-pixel level color balance compensation system for an OLED display panel based on De-Mura compensation technology, including a display driver integrated circuit for calculating compensation data:

[0042] (1) Decompress the compensation parameters burned in step four to obtain sub-pixel level compensation parameters:

[0043]

[0044]

[0045]

[0046] wherein respectively represent the actual resolutions of the OLED panel corresponding to the R / G / B sub-pixels;

[0047] (2) Input data acquisition, denoted as wherein is taken as R / G / B;

[0048] (3) According to the formula

[0049]

[0050] perform compensation calculation on the R / G / B channels based on the compensation parameters and the input data to obtain the sub-pixel level ;

[0051] Output the brightness and chromaticity uniformity compensation results for terminal display.

[0052] The present invention aims at improving chromaticity uniformity through zonal adjustment. However, due to the differences in the response characteristics of different pixels and different arrangement patterns, the adjustment effect is not ideal and it is difficult to uniformly apply the parameters between different panels. Moreover, it requires the display driver integrated circuit (DDIC) to additionally occupy the digital circuit design area, resulting in increased power consumption. On the existing brightness De-Mura processing flow, the compensation coefficient for improving chromaticity uniformity is applied to the brightness uniformity compensation parameters, and chromaticity uniformity compensation at the sub-pixel level can be achieved in the same way as brightness uniformity compensation. It can adapt to the response characteristics of different pixels and different arrangement patterns, and at the same time, it does not require additional digital circuit design area, saving the power consumption of the DDIC. The DDIC only needs one calculation to simultaneously achieve the brightness and chromaticity uniformity compensation of the OLED display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 shows the sub-pixel level color balance compensation process of the OLED display panel based on the De-Mura compensation technology;

[0054] Figure 2 shows the compensation implementation process of the display driver integrated circuit. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0055] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0056] Please refer to Figure 1-2 , the present invention discloses a sub-pixel level color balance compensation method for an OLED display panel based on De-Mura compensation technology, such as the preprocessing part of the brightness and chromaticity uniformity compensation parameters shown in Figure 1 .

[0057] Among them, the steps for realizing the brightness uniformity compensation part based on brightness data are as follows: First, capture multiple gray levels (for example: five gray levels of 32 / 64 / 128 / 192 / 255) of three channels R / G / B (Red: red, Green: green, Blue: blue) through a brightness industrial camera, a total of 3×5 groups of brightness data. The captured data is used in the De-Mura preprocessing process to generate brightness uniformity compensation parameters and a burn-in file, and the file is burned into the DDIC.

[0058] The steps for realizing the final chromaticity uniformity compensation coefficient part based on chromaticity data and brightness uniformity compensation parameters are as follows: Based on the brightness uniformity compensation result, capture the W (White: white) gray level (for example: 128 gray level, and the captured gray levels can be increased according to the chromaticity performance) through a chromaticity industrial camera to obtain chromaticity data. The captured data is used in the De-Mura preprocessing process to generate chromaticity uniformity compensation coefficients and apply them to the above-mentioned brightness uniformity compensation parameters to generate a final burn-in file for synchronously improving the brightness and chromaticity uniformity performance, and the file is burned into the DDIC.

[0059] The specific implementation process is as follows:

[0060] Step 1: Start, and the brightness industrial camera takes the first brightness data shot;

[0061] Step 2: Obtain the brightness data of different gray levels of three channels R / G / B;

[0062] Step 3: Perform brightness uniformity compensation processing;

[0063] Step 4: Generate brightness uniformity compensation parameters and a burn-in file, and burn them into the display driver integrated circuit;

[0064] Step 5: Judge whether chromaticity uniformity correction is required. If so, the chromaticity industrial camera takes the second chromaticity data shot, obtains the chromaticity data of different gray levels of the W picture, performs chromaticity uniformity compensation processing, generates chromaticity uniformity compensation coefficients and a burn-in file, and burns them into the display driver integrated circuit; if not, end.

[0065] The brightness data in Step 2 includes:

[0066] The brightness data of a total of 3×5 groups of sub-pixel points corresponding to five gray levels of 32, 64, 128, 192, and 255. The captured data is used in the De-Mura preprocessing process.

[0067] The process of brightness uniformity compensation in Step 3 is as follows:

[0068] Perform the following fitting process on the acquired brightness data:

[0069] (i) The basic formula for fitting is shown in Formula (1):

[0070]

[0071] where represents brightness, represents gray level, is an exponential parameter, is a linear parameter related to brightness. This formula is used to describe the relationship between different gray levels and brightness for subsequent calculation of compensation parameters;

[0072] (ii) The calculation process of sub-pixel level brightness uniformity compensation parameters is shown in Formula (2):

[0073]

[0074] where in and the two parameters are used to describe the target brightness parameters, in and the parameters are used to describe the sub-pixel compensation parameters. According to the input gray level and the parameter relationship, the corresponding output gray level of the sub-pixel is obtained;

[0075] (iii) The above Formula (2) can be expressed in the form of the following Formula (3):

[0076]

[0077] Let , then Formula (3) can be re-expressed as Formula (4)

[0078]

[0079] and Perform the above calculation process on the R / G / B three sub-pixels respectively, and the results are recorded as , , Take them as R / G / B.

[0080] The process of chromaticity uniformity compensation in Step 5 is as follows:

[0081] By introducing the uniformity compensation coefficient The original input grayscale is corrected to improve chromaticity uniformity. This process is expressed as Equation (5):

[0082]

[0083] For ease of derivation, Equation (5) is expanded to obtain Equation (6):

[0084]

[0085] Equation (6) is further expressed as Equation (7):

[0086]

[0087] In Equation (7), is denoted as , and is denoted as , obtaining Equation (8):

[0088]

[0089] Combining Equations (4) and (8), it can be seen that when the chromaticity correction coefficient is obtained, based on the De-Mura process, by modifying the compensation parameter being , the chromaticity uniformity correction function can be achieved synchronously.

[0090] The compensation parameter calculated in Step 4 is compressed to generate a burn-in file and burned into the display driver integrated circuit. The chromaticity industrial camera takes a second picture of the W screen.

[0091] The present invention supports flexible selection of the captured grayscale screen, and determines the captured screen based on the chromaticity performance of the W screen under different grayscales:

[0092] When the color conditions of different grayscale screens are the same, only one screen needs to be captured;

[0093] When the color conditions of different grayscale screens are different, multiple screens are captured. The W screen is captured by the chromaticity industrial camera to obtain the brightness data of each pixel sub-pixels R / G / B under the W screen. According to the R / G / B brightness data ratio coefficient of the selected target position, the average value of the captured brightness data in this area is denoted as , , and the actual sub-pixel ratio coefficient is calculated from the photographed data:

[0094] Denote the sub-pixel captured brightness data of the th pixel as , , the compensation adjustment coefficient of the sub-pixel is / 、 / 、 / , and the compensation coefficient at this position is obtained. .

[0095] When shooting single data, based on the compensation coefficient and the compensation parameter , calculate the R / G / B color uniformity compensation parameter according to the formula ;

[0096] When shooting multiple gray levels, apply the compensation coefficients calculated under different gray levels to the R / G / B shooting luminance data of the corresponding gray levels of the luminance industrial camera, and fit and calculate new and , where are the multiple gray levels shot; the chromaticity uniformity performance under different gray levels can be taken into account.

[0097] Compress the finally calculated OLED panel full sub-pixel compensation parameters and to generate a burn-in file and burn it into the display driver integrated circuit.

[0098] It should be noted that the , , , and other parameters involved in the actual compensation parameter calculation should be calculated separately based on the R / G / B three channels.

[0099] In addition, the present invention also provides an OLED display panel sub-pixel level color balance compensation system based on De-Mura compensation technology, which is used to implement an OLED display panel sub-pixel level color balance compensation method based on De-Mura compensation technology, including the display driver integrated circuit calculating compensation data:

[0100] (1) Decompress the compensation parameters burned in step four to obtain sub-pixel level compensation parameters:

[0101]

[0102]

[0103]

[0104] Where respectively represent the actual resolutions corresponding to the R / G / B sub-pixels of the OLED panel;

[0105] (2) Input data acquisition, denoted as , where is taken as R / G / B;

[0106] (3) According to the formula

[0107] ;

[0108] Based on the compensation parameters and the input data, perform compensation calculations on the R / G / B channels to obtain the sub-pixel level ;

[0109] Output the chromaticity uniformity compensation result for terminal display.

[0110] The specific implementation process is as Figure 2 shown:

[0111] (1) Start;

[0112] (2) The DDIC reads the compensation data stored in the memory;

[0113] (3) Determine whether the chromaticity uniformity is corrected. If it is, perform uniformity compensation processing on the brightness and chromaticity; if not, only perform compensation processing on the brightness uniformity;

[0114] (4) After the above processing is completed, end the process.

[0115] The technical effects of the present invention are as follows: Based on the fitting parameters representing data characteristics and the chromaticity compensation coefficients, an accurate fitting model is established, realizing a perfect integration with the hardware system. It significantly improves the chromaticity uniformity of the OLED panel, and only requires one calculation to generate accurate compensation predictions at the sub-pixel level. By integrating the chromaticity equalization coefficients through the De-Mura process, the occupation of computing resources is significantly reduced, and the performance of the hardware device is significantly improved. The system can also flexibly adjust the captured image according to the needs of the actual display device. By reasonably calculating the correction coefficients, it ensures that each output color in the subsequent color processing process can be accurately restored and the uniformity is improved, ultimately achieving high color consistency performance of the OLED display panel.

[0116] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is limited by the appended claims and their equivalents.

Claims

1. A sub-pixel color balance compensation method for an OLED display panel based on De-Mura compensation technology, characterized in that: include: Step 1: Start, the brightness industrial camera takes the first brightness data shot; Step 2: Obtain brightness data of three channels R / G / B at different grayscales; Step 3: Perform brightness uniformity compensation processing; Step 4: Generate brightness uniformity compensation parameters and burning files, and burn the display driver integrated circuit; Step 5: Determine whether chromaticity uniformity correction is required. If so, the chromaticity industrial camera performs a second chromaticity data capture, obtains chromaticity data of different grayscales of the W screen, performs chromaticity uniformity compensation processing, generates chromaticity uniformity compensation coefficients and burning files, and burns the display driver integrated circuit; If not, then end; The brightness data in step 2 includes: A total of 3×5 groups of sub-pixel brightness data corresponding to the five grayscales of 32, 64, 128, 192, and 255 are used for De-Mura preprocessing; Step 3 The process of brightness uniformity compensation is as follows: The brightness data obtained in step 2 is subjected to the following fitting process: (i) The basic fitting formula is shown in formula (1): （1）； in Indicates brightness, Represents grayscale, is the exponential parameter, is a linear parameter related to brightness. This formula is used to describe the relationship between different grayscales and brightness for subsequent compensation parameter calculation; (ii) The calculation process of the brightness uniformity compensation parameter at the sub-pixel level is shown in formula (2): （2）； in In and Two parameters are used to describe the target brightness. In and Parameters are used to describe the compensation parameters of sub-pixels, based on the input grayscale The corresponding output grayscale of the sub-pixel is obtained by the relationship between the parameters ; (iii) The above formula (2) is expressed in the form of the following formula (3): （3）； make , formula (3) is re-expressed as formula (4) （4）； and The above calculation process is performed on the three sub-pixels R / G / B respectively, and the results are recorded as , , Take it as R / G / B; Step 5 The process of color uniformity compensation is as follows: By introducing the uniformity compensation factor , for the original input grayscale Correction is performed to improve the chromaticity uniformity. This process is expressed as formula (5): （5）； To facilitate derivation, expand formula (5) to obtain formula (6): （6）； Formula (6) is further expressed as formula (7): （7）； In formula (7), Recorded as , and Recorded as , we get formula (8): （8）； Combining formulas (4) and (8), we can see that when the chromaticity correction coefficient is obtained After that, based on the De-Mura process, the compensation parameters are modified for The chromaticity uniformity correction function is realized simultaneously.

2. The method for sub-pixel color balance compensation of an OLED display panel based on De-Mura compensation technology according to claim 1, characterized in that: The compensation parameters calculated in step 4 are compressed to generate a burning file and burned into the display driver integrated circuit. The chromaticity industrial camera takes a second photo of the W screen: When the color conditions of different grayscale images are consistent, you only need to shoot one image; When the color conditions of different grayscale images are different, multiple images are captured, and W images are captured by a chromaticity industrial camera to obtain the brightness data of each pixel sub-pixel R / G / B under the W image. According to the R / G / B brightness data ratio coefficient of the selected target position, the average brightness data of the area is recorded as , , and the actual sub-pixel ratio coefficient is calculated from the photographic data: The first The sub-pixel brightness data of pixels is recorded as , , then the compensation adjustment coefficient of the sub-pixel is / , / , / , get the location Compensation coefficient at .

3. The method for sub-pixel color balance compensation of an OLED display panel based on De-Mura compensation technology according to claim 2, characterized in that: When shooting multiple grayscales, the compensation coefficients calculated under different grayscales are Applied to the brightness data of R / G / B corresponding to the grayscale of the brightness industrial camera, the new and ,in Multiple grayscales for shooting; The final calculated OLED panel full sub-pixel compensation parameters and After compression, a burning file is generated and the display driver integrated circuit is burned.

4. A sub-pixel color balance compensation system for an OLED display panel based on De-Mura compensation technology, used to implement the sub-pixel color balance compensation method for an OLED display panel based on De-Mura compensation technology as described in claim 3, characterized in that: Display driver IC calculation compensation data: (1) Decompress the compensation parameters burned in step 5 to obtain the compensation parameters at the sub-pixel level: ； in Respectively represent the actual resolution of the OLED panel corresponding to R / G / B sub-pixels; (2) Input data acquisition, denoted as ,in Take it as R / G / B; (3) According to the formula （8）； Compensation calculation is performed on the R / G / B channels based on the compensation parameters and input data to obtain sub-pixel level ; Output brightness and color uniformity compensation results for terminal display.

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