# US 11,115,563 B2 · Method and apparatus for nonlinear interpolation color conversion using look up tables > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,115,563 B2 - Document ID: US11115563B2 - Status: Granted - Kind: B2 - Application number: 16/022,999 - Filed: 2018-06-29 - Published: 2020-01-02 - Granted: 2021-09-07 - Earliest claimed: 2018-06-29 - Assignees: ATI Technologies ULC - Applicants: ATI Technologies ULC - Inventors: Keith Lee - Web page: https://patentgrep.com/patent/US11115563B2 ## CPC - H04N 1/6019: {using look-up tables (H04N1/6025 takes precedence)} - H04N 1/6058: {Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut} - G06T 1/20: Processor architectures; Processor configuration, e.g. pipelining - G06T 3/4007: based on interpolation, e.g. bilinear interpolation (image demosaicing G06T3/4015; edge-driven or edge-based scaling G06T3/403) - G09G 3/2003: {Display of colours (specific for liquid crystal displays G09G3/3607)} - H04N 19/80: Details of filtering operations specially adapted for video compression, e.g. for pixel interpolation (H04N19/635, H04N19/86 take precedence) - H04N 23/741: by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors - G09G 2320/0666: for control of colour parameters, e.g. colour temperature - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL - 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 and apparatus obtains a source image having a plurality of source color gamut pixels in a source color gamut. The method and apparatus converts the plurality of source color gamut pixels to a plurality of corresponding target color gamut pixels using non-linear interpolation of a plurality of output pixel values from a reduced 3-D look-up table (LUT) for a target color gamut. The method and apparatus provides, for display, the plurality of target color gamut pixels (e.g., one or more pixels) on a target color gamut display. ## Claims ### Claim 1 A method of mapping between color gamuts comprising: obtaining, by an apparatus, a source image having a plurality of source color gamut pixels in a source color gamut; converting, by the apparatus, the plurality of source color gamut pixels to a plurality of corresponding narrower target color gamut pixels using non-linear interpolation of a plurality of output pixel values from a reduced 3 dimensional (3-D) look-up table (LUT) corresponding to a target color gamut, wherein the reduced 3-D LUT comprises a plurality of displayable target color values representing vertices of a plurality of sub-cubes that represent less than all entries within the target color gamut; and providing, for display, by the apparatus, the plurality of corresponding target color gamut pixels on a target color gamut display. ### Claim 2 (depends on 1) The method of claim 1, wherein the converting the plurality of source color gamut pixels to the plurality of corresponding target color gamut pixels comprises performing a first non-linear interpolation for a plurality of first pixel values from the reduced 3-D LUT that is different from a second non-linear interpolation for a plurality of second pixel values from the reduced 3-D LUT. ### Claim 3 (depends on 2) The method of claim 2, wherein the plurality of first pixel values from the reduced 3-D LUT correspond to vertices of a sub-cube within the target color gamut and wherein the converting the plurality of source color gamut pixels to the plurality of corresponding target color gamut pixels further comprises: determining, based on the plurality of first pixel values from the reduced 3-D LUT, a set of polynomial coefficients for the sub-cube, and wherein the performing the first non-linear interpolation is based on the set of polynomial coefficients. ### Claim 4 (depends on 3) The method of claim 3, wherein the performing the first non-linear interpolation based on the set of polynomial coefficients is prior to performing a tetrahedral interpolation calculation or a tri-linear interpolation calculation. ### Claim 5 (depends on 3) The method of claim 3, wherein a graphics driver calculates the set of polynomial coefficients by performing a Taylor Series transform based on the vertices of the sub-cube within the target color gamut. ### Claim 6 (depends on 2) The method of claim 2, wherein the first non-linear interpolation is a piecewise linear curve or a polynomial equation. ### Claim 7 (depends on 1) The method of claim 1, wherein the converting the plurality of source color gamut pixels to the plurality of corresponding target color gamut pixels is performed by a 3-D engine. ### Claim 8 (depends on 1) The method of claim 1, wherein the converting the plurality of source color gamut pixels to the plurality of corresponding target color gamut pixels is performed by a video encoder, and wherein the obtaining the plurality of source color gamut pixels comprises obtaining the plurality of source color gamut pixels from a server via an internet connection. ### Claim 9 (depends on 1) The method of claim 1, the converting the plurality of source color gamut pixels to the plurality of corresponding target color gamut pixels is performed by a display engine, and wherein the display engine performs tone mapping operations for the target color gamut display. ### Claim 10 An apparatus comprising: non-linear interpolation color conversion logic configured to: obtain a source image having a plurality of source color gamut pixels in a source color gamut; convert the plurality of source color gamut pixels to a plurality of corresponding narrower target color gamut pixels using non-linear interpolation of a plurality of output pixel values from a reduced 3-D LUT corresponding to a target color gamut, the 3-D LUT comprising a plurality of displayable target color values representing vertices of a plurality of sub-cubes that represent less than all entries within the target color gamut; and provide for display the plurality of corresponding target color gamut pixels on a target color gamut display. ### Claim 11 (depends on 10) The apparatus of claim 10, wherein the non-linear interpolation color conversion logic converts the plurality of source color gamut pixels to the plurality of corresponding target color gamut pixels by performing a first non-linear interpolation for a plurality of first pixel values from the reduced 3-D LUT that is different from a second non-linear interpolation for a plurality of second pixel values from the reduced 3-D LUT. ### Claim 12 (depends on 11) The apparatus of claim 11, wherein the plurality of first pixel values from the reduced 3-D LUT correspond to vertices of a sub-cube within the target color gamut and wherein non-linear interpolation color conversion logic converts the plurality of source color gamut pixels to the plurality of corresponding target color gamut pixels by: determining, based on the plurality of first pixel values from the reduced 3-D LUT, a set of polynomial coefficients for the sub-cube, and wherein the performing the first non-linear interpolation is based on the set of polynomial coefficients. ### Claim 13 (depends on 12) The apparatus of claim 12, wherein the non-linear interpolation color conversion logic performs the first non-linear interpolation prior to performing a tetrahedral interpolation calculation or a tri-linear interpolation calculation. ### Claim 14 (depends on 12) The apparatus of claim 12, further comprising: a processor comprising a graphics driver, wherein the graphics driver is configured to calculate the set of polynomial coefficients by performing a Taylor Series transform based on the vertices of the sub-cube within the target color gamut. ### Claim 15 (depends on 12) The apparatus of claim 12, wherein the plurality of second pixel values from the reduced 3-D LUT correspond to vertices of a second sub-cube and wherein non-linear interpolation color conversion logic converts the plurality of source color gamut pixels to the plurality of corresponding target color gamut pixels by: determining, based on the plurality of second pixel values from the reduced 3-D LUT, a second set of polynomial coefficients for the second sub-cube, wherein the second set of polynomial coefficients is different from the set of polynomial coefficients; and performing the second non-linear interpolation based on the second set of polynomial coefficients. ### Claim 16 (depends on 11) The apparatus of claim 11, wherein the first non-linear interpolation is a piecewise linear curve or a polynomial equation. ### Claim 17 (depends on 10) The apparatus of claim 10, further comprising: a video encoder, wherein the video encoder comprises the non-linear interpolation color conversion logic, and wherein the video encoder is configured to: obtain the plurality of source color gamut pixels from a server via an internet connection. ### Claim 18 (depends on 10) The apparatus of claim 10, further comprising: a display engine, wherein the display engine comprises the non-linear interpolation color conversion logic, and wherein the display engine performs tone mapping operations for the target color gamut display. ### Claim 19 (depends on 10) The apparatus of claim 10, further comprising: a 3-D engine, wherein the 3-D engine comprises the non-linear interpolation color conversion logic; and a texture cache, wherein the texture cache stores the reduced 3-D LUT corresponding to the target color gamut. ### Claim 20 An integrated circuit comprising: a first processor, wherein the first processor comprises: non-linear interpolation color conversion logic configured to: obtain a source image having a plurality of source color gamut pixels in a source color gamut; obtain a reduced 3-D LUT corresponding to a target color gamut, the reduced 3-D LUT comprises a plurality of displayable target color values representing vertices of a plurality of sub-cubes; select, on a pixel-by-pixel basis, a plurality of pixel values from the plurality of displayable target color values, a plurality of pixel values representing vertices of a sub-cube of the plurality of sub-cubes within the target color gamut; determine, based on a non-linear interpolation of the vertices of the sub-cube, a set of polynomial coefficients for the sub-cube representing a Taylor Series transform; convert, based on the set of polynomial coefficients for the sub-cube, the plurality of source color gamut pixels to a plurality of corresponding target color gamut pixels using the non-linear interpolation of the vertices of the sub-cube; and provide, for display, the plurality of corresponding target color gamut pixels on a target color gamut display.