# US 9,436,977 B2 · Grayscale compensation method and system for defect on display panel > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,436,977 B2 - Document ID: US9436977B2 - Status: Granted - Kind: B2 - Application number: 14/425,042 - Filed: 2015-01-14 - Published: 2016-06-30 - Granted: 2016-09-06 - Earliest claimed: 2014-12-29 - Assignees: Shenzhen China Star Optoelectronics Technology Co., Ltd. - Applicants: Shenzhen China Star Optoelectronics Technology Co., Ltd. - Inventors: Houliang Hu; Ping-sheng Kuo; Li-wei Chu - Web page: https://patentgrep.com/patent/US9436977B2 ## CPC - G09G 3/006: {Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays (testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309)} - G09G 3/20: for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix {no fixed position being assigned to or needed to be assigned to the individual characters or partial characters} - G09G 3/36: using liquid crystals - G09G 5/10: Intensity circuits - G06T 2207/20172: Image enhancement details - G09G 2320/0233: Improving the luminance or brightness uniformity across the screen - G09G 2330/10: Dealing with defective pixels - G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00) - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract A method of grayscale compensation to defects on a display panel includes: (A) obtaining a set of coordination of the defect on the display panel, and determining a defect area where the defect locates based on the set of coordination; (B) obtaining a gamma curve of the defect, a gamma curve of a background of the defect area, and a standard gamma curve of the background of the display panel; (C) obtaining a standard gamma curve of the defect and a standard gamma curve of the background of the defect area; and (D) calculating a grayscale-compensation value for each grayscale of the defect, based on the standard gamma curve and the standard gamma curve of the background of the defect area. The present invention is to reduce calculation, and to achieve the best compensation to defects on a display panel. ## Claims ### Claim 1 A method of grayscale compensation to defects on a display panel, comprising: (A) obtaining a set of coordination of the defect on the display panel, and determining a defect area where the defect locates based on the set of coordination; (B) obtaining a gamma curve of the defect, a gamma curve of a background of the defect area, and a standard gamma curve of the background of the display panel; (C) obtaining a standard gamma curve of the defect and a standard gamma curve of the background of the defect area, based on the gamma curve of the defect, the gamma curve of the background of the defect area, and the standard gamma curve of the background of the display panel; and (D) calculating a grayscale-compensation value for each grayscale of the defect, based on the standard gamma curve and the standard gamma curve of the background of the defect area; wherein the step (C) of obtaining a standard gamma curve of the defect and a standard gamma curve of the background of the defect area comprises: obtaining a first mapping curve of a brightness value of the defect and a brightness value of the background of the display panel, and a second mapping curve of a brightness value of the background of the defect area and the brightness value of the background of the display panel, based on the gamma curve of the defect, the gamma curve of the background of the defect area, and the standard gamma curve of the background of the display panel; and obtaining the standard gamma curve of the defect and the standard gamma curve of the background of the defect area by the first mapping curve and the second mapping curve; and wherein before step (D), the method further comprises: determining if the defect is a compensable defect; and wherein in case that the defect as a compensable defect, performing step (D). ### Claim 2 (depends on 1) The method of claim 1, wherein a step of determining if the defect is a compensable defect comprises: determining the defect as a compensable defect, if a brightness value corresponding to a maximum grayscale of the standard gamma curve of the defect and a minimum grayscale of the standard gamma curve of the defect meet Equation 1 X ⁡ ( max ) - X ⁡ ( min ) max + 1 ≥ T , Equation ⁢ ⁢ 1 where max denotes to the maximum grayscale of the standard gamma curve of the defect, min to the minimum grayscale of the standard gamma curve of the defect, X(max) to the brightness value corresponding to the maximum grayscale, X(min) to the brightness value corresponding to the minimum grayscale, and T to a predetermined threshold. ### Claim 3 (depends on 1) The method of claim 1, wherein a step of determining if the defect is a compensable defect comprises: determining the defect as a compensable defect, if a brightness value corresponding to a maximum grayscale of the standard gamma curve of the defect and a minimum grayscale of the standard gamma curve of the defect meet Equation 1 X ⁡ ( max ) - X ⁡ ( min ) max + 1 ≥ T , Equation ⁢ ⁢ 1 where max denotes to the maximum grayscale of the standard gamma curve of the defect, min to the minimum grayscale of the standard gamma curve of the defect, X(max) to the brightness value corresponding to the maximum grayscale, X(min) to the brightness value corresponding to the minimum grayscale, and T to a predetermined threshold. ### Claim 4 (depends on 1) The method of claim 1, wherein the step (D) of calculating the grayscale compensation value of each grayscale based on the standard gamma curve of the defect and the standard gamma curve of the background of the defect area, is performed by Equation 2 Δgray=gray2(L)−gray1(L), Equation 2: where gray1(L) denotes to a grayscale of the defect obtained at a particular brightness value L based on the standard gamma curve of the defect, gray2(L) to a grayscale of the background of the defect area obtained at the particular brightness value L based on the standard gamma curve of the background of the defect area, and Δgray to a grayscale compensation value of the grayscale gray1(L) of the defect. ### Claim 5 A grayscale compensation system for a defect on a display panel, comprising: a location detector, configured to obtain a set of coordination of the defect on the display panel, and to determine a defect area where the defect locates based on the set of coordination; a gamma-curve detector, configured to obtain a gamma curve of the defect, a gamma curve of a background of the defect area, and a standard gamma curve of the background of the display panel; a standard-gamma-curve detector, configured to obtain a standard gamma curve of the defect and a standard gamma curve of the background of the defect area, based on the gamma curve of the defect, the gamma curve of the background of the defect area, and the standard gamma curve of the background of the display panel; and a calculator, configured to calculate a grayscale-compensation value for each grayscale of the defect, based on the standard gamma curve and the standard gamma curve of the background of the defect area; wherein the standard-gamma-curve detector is further configured to obtain a first mapping curve of a brightness value of the defect and a brightness value of the background of the display panel, and a second mapping curve of a brightness value of the background of the defect area and the brightness value of the background of the display panel, based on the gamma curve of the defect, the gamma curve of the background of the defect area, and the standard gamma curve of the background of the display panel; and to obtain the standard gamma curve of the defect and the standard gamma curve of the background of the defect area by the first mapping curve and the second mapping curve; and a compensable-defect detector, configured to determine if the defect is a compensable defect. ### Claim 6 (depends on 5) The grayscale compensation system of claim 5, wherein the compensable-defect detector further configured to determine the defect as a compensable defect if a brightness value corresponding to a maximum grayscale of the standard gamma curve of the defect and a minimum grayscale of the standard gamma curve of the defect meet Equation 1 X ⁡ ( max ) - X ⁡ ( min ) max + 1 ≥ T , Equation ⁢ ⁢ 1 where max denotes to the maximum grayscale of the standard gamma curve of the defect, min to the minimum grayscale of the standard gamma curve of the defect, X(max) to the brightness value corresponding to the maximum grayscale, X(min) to the brightness value corresponding to the minimum grayscale, and T to a predetermined threshold. ### Claim 7 (depends on 5) The grayscale compensation system of claim 5, wherein the compensable-defect detector further configured to determine the defect as a compensable defect if a brightness value corresponding to a maximum grayscale of the standard gamma curve of the defect and a minimum grayscale of the standard gamma curve of the defect meet Equation 1 X ⁡ ( max ) - X ⁡ ( min ) max + 1 ≥ T , Equation ⁢ ⁢ 1 where max denotes to the maximum grayscale of the standard gamma curve of the defect, min to the minimum grayscale of the standard gamma curve of the defect, X(max) to the brightness value corresponding to the maximum grayscale, X(min) to the brightness value corresponding to the minimum grayscale, and T to a predetermined threshold. ### Claim 8 (depends on 5) The grayscale compensation system of claim 5, wherein the calculator further configured to calculate out the grayscale compensation value of each grayscale, based on the standard gamma curve of the defect and the standard gamma curve of the background of the defect area, by Equation 2 Δgray=gray2(L)−gray1(L), Equation 2: where gray1(L) denotes to a grayscale of the defect obtained at a particular brightness value L based on the standard gamma curve of the defect, gray2(L) to a grayscale of the background of the defect area obtained at the particular brightness value L based on the standard gamma curve of the background of the defect area, and Δgray to a grayscale compensation value of the grayscale gray1(L) of the defect. ### Claim 9 (depends on 5) The grayscale compensation system of claim 5, wherein in case that the compensable-defect determining unit determines the defect as a compensable defect, the calculating unit calculates out the grayscale-compensation value for each grayscale of the compensable defect based on the standard gamma curve of the compensable defect and the standard gamma curve of the background of the defect area wherein the compensable defect located.