# US 12,183,235 B2 · Predictive gamma algorithm for multiple display refresh rates > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,183,235 B2 - Document ID: US12183235B2 - Status: Granted - Kind: B2 - Application number: 17/998,227 - Filed: 2021-05-25 - Published: 2023-08-31 - Granted: 2024-12-31 - Earliest claimed: 2020-07-07 - Assignees: Google Inc. - Applicants: Google LLC - Inventors: Chien-Hui Wen; Hsin-Yu Chen; Ken Kok Foo; John William Kaehler - Web page: https://patentgrep.com/patent/US12183235B2 ## CPC - 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 3/2003: {Display of colours (specific for liquid crystal displays G09G3/3607)} - G09G 2320/0233: Improving the luminance or brightness uniformity across the screen - G09G 2320/0242: Compensation of deficiencies in the appearance of colours - G09G 2320/0247: Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes - G09G 2320/0276: for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction - G09G 2320/029: by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel - G09G 2320/0626: for control of overall brightness - G09G 2320/0673: for control of gamma adjustment, e.g. selecting another gamma curve - G09G 2340/0435: Change or adaptation of the frame rate of the video stream - G09G 2360/145: the light originating from the display screen - G09G 2360/16: Calculation or use of calculated indices related to luminance levels in display data - 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) ## Abstract A method may include measuring, from a device having a display panel configured to operate at a first refresh rate or a second refresh rate, a difference in luminance of the display panel between the first refresh rate and the second refresh rate for an input gray level. The method may also include applying, based on the measured difference in luminance, a value offset to a default gamma value used by the device for the input gray level when the display panel is operating at the second refresh rate, thereby generating a new gamma value. The method may further include storing, at the device, the new gamma value, where subsequent to the storing, the device is configured to override the default gamma value for the input gray level with the new gamma value when the display panel is operating at the second refresh rate. ## Claims ### Claim 1 A method comprising: measuring, from a device having a display panel configured to operate at a first refresh rate or a second refresh rate, a difference in color of the display panel between the first refresh rate and the second refresh rate for an input gray level; applying, based on the at least one measured difference, a value offset to a first default gamma value used by the device for the input gray level when the display panel is operating at the second refresh rate, thereby generating a new gamma value; and storing, at the device, the new gamma value wherein subsequent to the storing, the device is configured to override the first default gamma value for the input gray level with the new gamma value when the display panel is operating at the second refresh rate, and wherein the display panel has a plurality of color channels, wherein the first default gamma value comprises respective register values for the plurality of color channels, and wherein the value offset comprises an offset to at least one of the register values of the first default gamma value. ### Claim 2 (depends on 1) The method of claim 1, wherein the plurality of color channels comprise red, green and blue (RGB) color channels. ### Claim 3 (depends on 1) The method of claim 1, further comprising: measuring a difference in luminance of the display panel between the first refresh rate and the second refresh rate for the input gray level; making a determination that at least one of a second measured difference in luminance or a second measured difference in color of the display panel between the first refresh rate and the second refresh rate for the input gray level is greater than a predefined threshold; in response to the determination, applying, based on the at least one second measured difference, a second value offset to the new gamma value, thereby generating a second new gamma value; and storing, at the device, the second new gamma value, wherein subsequent to storing the second new gamma value, the device is configured to override the first default gamma value for the input gray level with the second new gamma value when the display panel is operating at the second refresh rate. ### Claim 4 (depends on 3) The method of claim 3, wherein differences in luminance and differences in color of the display panel are measured as percentage differences, and wherein the predefined threshold is in range between 5% and 95%. ### Claim 5 (depends on 3) The method of claim 3, further comprising: measuring, from the device, at least one of a second difference in luminance or a second difference in color of the display panel between the first refresh rate and the second refresh rate for a second input gray level; applying, based on the at least one second measured difference, a second value offset to a second default gamma value used by the device for the second input gray level when the display panel is operating at the second refresh rate, thereby generating a second new gamma value; and storing, at the device, the second new gamma value, wherein subsequent to storing the second new gamma value, the device is configured to override the second default gamma value for the second input gray level with the second new gamma value when the display panel is operating at the second refresh rate. ### Claim 6 (depends on 5) The method of claim 5, wherein the device is configured with multiple gamma correction curves, and wherein the first and second default gamma values are determined from a same gamma correction curve. ### Claim 7 (depends on 5) The method of claim 5, wherein the device is configured with multiple gamma correction curves, and wherein the first and second default gamma values are determined from different gamma correction curves. ### Claim 8 (depends on 1) The method of claim 1, wherein the input gray level is a threshold low gray level. ### Claim 9 (depends on 1) The method of claim 1, wherein the measuring and applying are performed by the device. ### Claim 10 (depends on 1) The method of claim 1, wherein the measuring and applying are performed by a second device communicatively coupled to the device. ### Claim 11 (depends on 1) The method of claim 1, wherein the measuring is performed by a second device communicatively coupled to the device, and wherein the applying is performed by the device. ### Claim 12 (depends on 1) The method of claim 1, wherein the first refresh rate is 60 Hz and wherein the second refresh rate is 90 Hz. ### Claim 13 (depends on 1) The method of claim 1, wherein the storing comprises storing the new gamma value in a boot image of the device. ### Claim 14 (depends on 1) The method of claim 1, wherein the value offset is determined, at least in part, based on the first default gamma value used by the device for the input gray level when the display panel is operating at the first refresh rate. ### Claim 15 (depends on 1) The method of claim 1, further comprising: determining, based on a measured difference in luminance and from a set of mappings between: (i) differences in luminance or differences in color, and (ii) value offsets, the value offset. ### Claim 16 (depends on 15) The method of claim 15, wherein the differences in luminance are grouped into buckets, and wherein luminance differences in each bucket map to a same value offset. ### Claim 17 (depends on 16) The method of claim 16, wherein the buckets are determined based on magnitudes of differences in luminance. ### Claim 18 (depends on 15) The method of claim 15, wherein the differences in color are grouped into buckets, and wherein color differences in each bucket map to a same value offset. ### Claim 19 (depends on 18) The method of claim 18, wherein the buckets are determined based on magnitudes of differences in color. ### Claim 20 (depends on 15) The method of claim 15, wherein the set of mappings are determined based on analysis of a group of devices that are related to the device. ### Claim 21 (depends on 1) The method of claim 1, further comprising: measuring, from the device, a delta luminance, being a difference in luminance of the display panel between the first refresh rate and the second refresh rate for the input gray level, wherein the applying of the value offset is based on the measured delta luminance, and wherein the value offset is from one of a series of offset tables that detail an offset value that should be applied for various delta luminances, defined as ranges of delta luminances, and updating register values for the input gray level until the delta luminance for the input gray level is less than a predefined threshold. ### Claim 22 A system comprising: one or more processors; and data storage, wherein the data storage has stored thereon computer-executable instructions that, when executed by the one or more processors, cause the system to carry out operations comprising: measuring, from a device having a display panel configured to operate at a first refresh rate or a second refresh rate, a difference in color of the display panel between the first refresh rate and the second refresh rate for an input gray level; applying, based on the at least one measured difference, a value offset to a default gamma value used by the device for the input gray level when the display panel is operating at the second refresh rate, thereby generating a new gamma value, wherein the display panel has a plurality of color channels, wherein the default gamma value comprises respective register values for the plurality of color channels, and wherein the value offset comprises an offset to at least one of the register values of the default gamma value; and providing instructions to the device to override the default gamma value for the input gray level with the new gamma value when the display panel is operating at the second refresh rate. ### Claim 23 A device comprising: a display panel configured to operate at a first refresh rate or a second refresh rate; and one or more processors configured to: receive a measured difference in color of the display panel between the first refresh rate and the second refresh rate for an input gray level; apply, based on the at least one measured difference, a value offset to a default gamma value used by the device for the input gray level when the display panel is operating at the second refresh rate, thereby generating a new gamma value; and store the new gamma value, wherein subsequent to the storing, the device is configured to override the default gamma value for the input gray level with the new gamma value when the display panel is operating at the second refresh rate, and wherein the display panel has a plurality of color channels, wherein the default gamma value comprises respective register values for the plurality of color channels, and wherein the value offset comprises an offset to at least one of the register values of the default gamma value.