# US 2019/0318696 A1 · Ambient light color compensation systems and methods for electronic device displays > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0318696 A1 - Document ID: US20190318696A1 - Status: Published application - Kind: A1 - Application number: 16/044,408 - Filed: 2018-07-24 - Published: 2019-10-17 - Earliest claimed: 2018-04-13 - Assignees: Apple Inc. - Applicants: Apple Inc. - Inventors: Francisco H. IMAI; Chi ZHANG; Adria FORES HERRANZ; Jiaying WU; Arthur L. SPENCE; Marc ALBRECHT - Web page: https://patentgrep.com/patent/US20190318696A1 ## CPC - G09G 3/3413: {Details of control of colour illumination sources} - G09G 3/2003: {Display of colours (specific for liquid crystal displays G09G3/3607)} - G09G 3/3607: {for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels (display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127)} - G09G 2320/0242: Compensation of deficiencies in the appearance of colours - G09G 2320/0666: for control of colour parameters, e.g. colour temperature - G09G 2340/06: Colour space transformation - G09G 2360/144: the light being ambient light - 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 Aspects of the subject technology relate to electronic devices with displays and ambient light sensors. An electronic device modifies the color of images to be displayed based on measured ambient light color. The modification is performed in a perceptually uniform color space and includes a determination of a bleaching effect of reflected ambient light, and a determination of a color correction factor to be applied within the perceptually uniform color space,7 based on the determined bleaching effect. The modification may also include an application of a strength factor that mitigates out-of-gamut colors in color compensated images. ## Claims ### Claim 1 An electronic device, comprising: a display having an array of display pixels configured to emit colored display light; an ambient light sensor; and processing circuitry configured to: transform an image to be displayed with the display to a perceptually uniform color space; obtain an ambient light measurement from the ambient light sensor; determine a color compensation factor based on the transformed image and the ambient light measurement; apply the color compensation factor to the transformed image; perform an inverse transform of the transformed image with the color compensation applied to obtain a compensated image; and provide the compensated image to the display, for display by the array of display pixels. ### Claim 2 (depends on 1) The electronic device of claim 1, wherein the processing circuitry is further configured to determine a spectral power distribution of ambient light in an environment of the electronic device based on the ambient light measurement. ### Claim 3 (depends on 2) The electronic device of claim 2, wherein the processing circuitry is further configured to determine reflected light tristimulus values for a reflected portion of the ambient light based on the spectral power distribution, and based on display spectral reflectance data and color matching data stored in memory of the electronic device. ### Claim 4 (depends on 3) The electronic device of claim 3, wherein the processing circuitry is further configured to determine image tristimulus values for the image. ### Claim 5 (depends on 4) The electronic device of claim 4, wherein the processing circuitry is further configured to determine bleached image tristimulus values by combining the reflected light tristimulus values and the image tristimulus values. ### Claim 6 (depends on 5) The electronic device of claim 5, wherein the processing circuitry is further configured to transform the bleached image tristimulus values to bleached image perceptually uniform color space values. ### Claim 7 (depends on 6) The electronic device of claim 6, wherein the processing circuitry is further configured to: transform the image to be displayed with the display to the perceptually uniform color space, at least in part by transforming the image tristimulus values to image perceptually uniform color space values; and determine the color compensation factor by combining the bleached image perceptually uniform color space values with the image perceptually uniform color space values. ### Claim 8 (depends on 7) The electronic device of claim 7, wherein the processing circuitry is further configured to: determine a color compensation strength based on the ambient light measurement; and apply the color compensation strength to the transformed image with the color compensation applied, prior to performing the inverse transform. ### Claim 9 (depends on 7) The electronic device of claim 7, wherein the image perceptually uniform color space values comprise a brightness value, a redness-greenness value, and a yellowness-blueness value for the image, and wherein the color compensation factor comprises a first compensation factor for the redness-greenness value and a second compensation factor for the yellowness-blueness value. ### Claim 10 An electronic device, comprising: a display having an array of display pixels configured to emit colored display light; an ambient light sensor; and processing circuitry configured to: obtain an ambient light measurement from the ambient light sensor; obtain an input image to be displayed by the display; determine expected reflection data based on the ambient light measurement and display spectral reflectance data; determine color bleaching data based on the expected reflection data and a transformation of the input image; determine a color correction factor based on the color bleaching data and the transformation of the input image; apply the color correction factor to the transformation of the input image; and generate a compensated output image for display based on the transformation of the input image with the color correction factor applied. ### Claim 11 (depends on 10) The electronic device of claim 10, wherein the display spectral reflectance data comprises a plurality of spectral reflectances of the display under a corresponding plurality of ambient light types. ### Claim 12 (depends on 11) The electronic device of claim 11, wherein the ambient light measurement comprises a brightness and a color of ambient light detected by the ambient light sensor. ### Claim 13 (depends on 12) The electronic device of claim 12, wherein the input image is a red-green-blue image, and wherein the processing circuitry is further configured to: determine tristimulus values for the red-green-blue image; determine image cone responses from the determined tristimulus values; and determine perceptually uniform color space values from the image cone responses to obtain the transformation of the input image. ### Claim 14 (depends on 13) The electronic device of claim 13, wherein the perceptually uniform color space values comprise a redness-greenness value and yellowness-blueness value for the input image. ### Claim 15 (depends on 14) The electronic device of claim 14, wherein the color correction factor comprises a first color correction factor for the redness-greenness value and a second color correction factor for the yellowness-blueness value. ### Claim 16 A method for operating an electronic device having a display, the method comprising: obtaining an image to be displayed by the display; obtaining a measurement of ambient light in an environment around the electronic device; transforming the image to a perceptually uniform color space; determining a color correction for the image based on the measurement of the ambient light and the transformed image; and generating a compensated image based on the transformed image and the color correction. ### Claim 17 (depends on 16) The method of claim 16, further comprising obtaining tristimulus values for a reflected portion of the ambient light. ### Claim 18 A method for operating an electronic device having a display, the method comprising: obtaining an image to be displayed by the display; obtaining a measurement of ambient light in an environment around the electronic device; obtaining reflected light tristimulus values; determining a color correction for the image based on the reflected light tristimulus values and a color transformation of the image; and generating a compensated image based on the color transformation of the image and the color correction. ### Claim 19 (depends on 18) The method of claim 18, wherein obtaining the reflected light tristimulus values comprises computing the reflected light tristimulus values directly from one or more channel readings of an ambient light sensor of the electronic device. ### Claim 20 (depends on 18) The method of claim 18, wherein obtaining the reflected light tristimulus values comprises determining a spectral power distribution of the ambient light based on the measurement of the ambient light. ### Claim 21 (depends on 20) The method of claim 20, wherein obtaining the reflected light tristimulus values further comprises integrating the spectral power distribution with a display spectral reflectance of the display and a color matching function.