# US 2017/0287149 A1 · Macropixel processing system, method and article > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0287149 A1 - Document ID: US20170287149A1 - Status: Published application - Kind: A1 - Application number: 15/088,934 - Filed: 2016-04-01 - Published: 2017-10-05 - Earliest claimed: 2016-04-01 - Assignees: STMicroelectronics (Grenoble 2) SAS - Applicants: STMicroelectronics (Grenoble 2) SAS - Inventors: Mathieu Thivin; Grégory Roffet - Web page: https://patentgrep.com/patent/US20170287149A1 ## CPC - H04N 25/447: by preserving the colour pattern with or without loss of information - H04N 23/843: {Demosaicing, e.g. interpolating colour pixel values} - H04N 23/85: for matrixing - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Tone mapping is performed by digital image processing circuitry on a macro-pixel basis. A luminance value of a macro-pixel of a digital image in a color space is determined. The macro-pixel includes a plurality of individual pixels. Respective tone-mapping gain values of each pixel of the macro-pixel are determined based on the determined luminance value of the macro-pixel. The determined tone-mapping gains are applied to the respective pixels of the macro-pixel. The color space may be a CFA color space, such as a Bayer color space. ## Claims ### Claim 1 A method, comprising: determining, using digital image processing circuitry, a luminance value of a macro-pixel of a digital image in a color space, the macro-pixel including a plurality of individual pixels; determining, using the digital image processing circuitry, respective gain values of each pixel of the macro-pixel based on the determined luminance value of the macro-pixel; and applying, using the digital image processing circuitry, the determined gain values to the respective pixels of the macro-pixel. ### Claim 2 (depends on 1) The method of claim 1, comprising: maintaining, using the digital image processing circuitry, a look-up table; and determining the respective gain values of the pixels of the macro-pixel based on the luminance value of the macro-pixel and the look-up table. ### Claim 3 (depends on 2) The method of claim 2, comprising: maintaining, using the digital image processing circuitry, luminance based histogram information; and maintaining, using the digital image processing circuitry, the look-up table based on the luminance based histogram information. ### Claim 4 (depends on 3) The method of claim 3, comprising: processing a plurality of macro-pixels of the digital image, wherein the maintaining the luminance based histogram information comprises generating a histogram based on half of the macro-pixels of the plurality of macro-pixels. ### Claim 5 (depends on 2) The method of claim 2 wherein the determining the respective gain values of the pixels of the macro-pixel based on the luminance value of the macro-pixel and the look-up table comprises performing a single look-up operation in the look-up table. ### Claim 6 (depends on 1) The method of claim 1 wherein each pixel of the macro-pixel has a single respective gain value. ### Claim 7 (depends on 1) The method of claim 1 wherein the color space is a Bayer color space. ### Claim 8 A device, comprising: luminance determination circuitry, which, in operation, determines a luminance value of a macro-pixel of a digital image in a color space, the macro-pixel including a plurality of individual pixels; gain determination circuitry, which in operation, determines respective gain values of each pixel of the macro-pixel based on the determined luminance value of the macro-pixel; and gain application circuitry, which, in operation, applies the determined gain values to the respective pixels of the macro-pixel. ### Claim 9 (depends on 8) The device of claim 8 wherein the gain determining circuitry comprises a look-up table and, in operation, the gain determining circuitry determines the respective gain values of the pixels of the macro-pixel based on the luminance value of the macro-pixel and the look-up table. ### Claim 10 (depends on 8) The device of claim 8, comprising: histogram generation circuitry, which, in operation, generates a histogram based on macro-pixel luminance historical information, wherein the gain determination circuitry, in operation, determines respective gain values of each pixel of the macro-pixel based on the determined luminance value of the macro-pixel and the histogram. ### Claim 11 (depends on 10) The device of claim 10 wherein the histogram generation circuitry, in operation, generates the histogram based on half of a plurality of macro-pixels of the digital image. ### Claim 12 (depends on 9) The device of claim 9 wherein the determining the respective gain values of the pixels of the macro-pixel based on the luminance value of the macro-pixel and the look-up table comprises performing a single look-up operation in the look-up table. ### Claim 13 (depends on 8) The device of claim 8 wherein each pixel of the macro-pixel has a single respective gain value. ### Claim 14 (depends on 8) The device of claim 8 wherein the color space is a color filter array (CFA) color space. ### Claim 15 (depends on 14) The device of claim 14 wherein the CFA color space is a Bayer color space. ### Claim 16 A system, comprising: an image sensor, which, in operation, generates digital images in a color space; and digital image tone mapping circuitry, which, in operation: determines a luminance value of a macro-pixel of a digital image in the color space, the macro-pixel including a plurality of individual pixels; determines respective gain values of each pixel of the macro-pixel based on the determined luminance value of the macro-pixel; and applies the determined gain values to the respective pixels of the macro-pixel. ### Claim 17 (depends on 16) The system of claim 16 wherein the digital image tone mapping circuitry comprises a look-up table and, in operation, the digital image tone mapping circuitry determines the respective gain values of the pixels of the macro-pixel based on the luminance value of the macro-pixel and the look-up table. ### Claim 18 (depends on 16) The system of claim 16 wherein the digital image tone mapping circuitry, in operation, generates a histogram based on macro-pixel luminance historical information and determines respective gain values of each pixel of the macro-pixel based on the determined luminance value of the macro-pixel and the histogram. ### Claim 19 (depends on 18) The system of claim 18 wherein the histogram is based on half of a plurality of macro-pixels of the digital image. ### Claim 20 (depends on 16) The system of claim 16 wherein the digital image tone mapping circuitry comprises a plurality of multipliers, which, in operation, multiple respective pixels of the macro-pixel by the respective gain values. ### Claim 21 (depends on 15) The system of claim 15 wherein the color space is a Bayer color space. ### Claim 22 A non-transitory computer-readable medium having contents which configure a digital image processing circuit to perform a tone mapping method, the tone mapping method comprising: determining a luminance value of a macro-pixel of a digital image in a color space, the macro-pixel including a plurality of individual pixels; determining respective gain values of each pixel of the macro-pixel based on the determined luminance value of the macro-pixel; and applying the determined gain values to the respective pixels of the macro-pixel. ### Claim 23 (depends on 22) The non-transitory computer-readable medium of claim 22 wherein the method comprises: maintaining a look-up table; and determining the respective gain values of the pixels of the macro-pixel based on the luminance value of the macro-pixel and the look-up table. ### Claim 24 (depends on 23) The non-transitory computer-readable medium of claim 23 wherein the method comprises: maintaining historical luminance information; and maintaining the look-up table based on the historical luminance information. ### Claim 25 (depends on 22) The non-transitory computer-readable medium of claim 22 wherein the color space is a color-filter-array (CFA) color space.