# US 2019/0174050 A1 · Methods and apparatus for reducing spatial flicker artifacts > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0174050 A1 - Document ID: US20190174050A1 - Status: Published application - Kind: A1 - Application number: 16/267,897 - Filed: 2019-02-05 - Published: 2019-06-06 - Earliest claimed: 2016-06-23 - Assignees: Semiconductor Components Industries, LLC - Applicants: Semiconductor Components Industries, LLC - Inventors: Manjunath SOMAYAJI; Rohit RANADE - Web page: https://patentgrep.com/patent/US20190174050A1 ## CPC - H04N 23/745: Detection of flicker frequency or suppression of flicker wherein the flicker is caused by illumination, e.g. due to fluorescent tube illumination or pulsed LED illumination - G09G 5/026: {Control of mixing and/or overlay of colours in general (G09G5/022 and G09G5/024 take precedence)} - G09G 5/377: for mixing or overlaying two or more graphic patterns (G09G5/02, G09G5/397 take precedence) - H04N 23/71: Circuitry for evaluating the brightness variation - H04N 23/741: by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors - H04N 25/13: characterised by the spectral characteristics of the filter elements - G09G 2320/02: Improving the quality of display appearance - G09G 2320/0247: Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - 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 Various embodiments of the present technology may comprise a method and apparatus for reducing spatial flicker artifacts in high dynamic range images produced from multiple image captures with differing integration times. The method and apparatus may comprise, in the image captures, measuring pixel intensity selecting pixels with a predetermined intensity thresholds, calculating a ratio based on a channel selection, normalizing the calculated ratio to an ideal ratio, and applying the normalized ratio to corresponding image pixels in a second image capture to produce a flicker-free image. ## Claims ### Claim 1 An imaging device comprising: an array of pixels arranged in rows and columns, wherein the array of pixels generates: first image pixel data corresponding to pixels having a first exposure time, and second image pixel data corresponding to pixels having a second exposure time, wherein the first exposure time is greater than the second exposure time; and wherein the pixels used to generate the first and second image pixel data have the same spatial locations within the array; a color filter overlaying the array pixels and comprising a plurality of color filters; and an image signal processor coupled to the array of pixels, wherein the image signal processor: receives the first image pixel data and second image pixel data; identifies valid and invalid image pixel data based on pixel data values; generate a ratio utilizing the valid image pixel data; wherein: the ratio comprises a first individual pixel value divided by a second individual pixel value; the first individual pixel value corresponds to a first color from the plurality of color filters; the second individual pixel value corresponds to a second color from the plurality of color filters that is different from the first color; and the first and second individual pixel values have a same exposure time; normalizes the computed ratio using an ideal ratio, wherein the ideal ratio is the first exposure time divided by the second exposure time; and modifies the second image pixel data using the normalized computed ratio. ### Claim 2 (depends on 1) The imaging device of claim 1, wherein the invalid pixel data comprises: first image pixel data with a value above a first predetermined threshold, and second image pixel data with a value below a second predetermined threshold. ### Claim 3 (depends on 1) The imaging device of claim 1, wherein the valid pixel data comprises first image pixel data with a value below a first predetermined threshold. ### Claim 4 (depends on 3) The imaging device of claim 3, wherein the valid pixel data further comprises second image pixel data with a value above a second predetermined threshold. ### Claim 5 (depends on 1) The imaging device of claim 1, wherein the image signal processor further identifies the valid image pixel data within a neighborhood of each identified invalid image pixel data. ### Claim 6 (depends on 5) The imaging device of claim 5, wherein the image signal processor computes a representative value for the identified valid image pixel data within the neighborhood of the identified invalid image pixel data and replacing the identified invalid image pixel data with the representative value. ### Claim 7 (depends on 1) The imaging device of claim 1, wherein the first and second individual pixel values are generated by pixels that share at least one of: a same row and a same column. ### Claim 8 (depends on 1) The imaging device of claim 1, wherein the first and second individual pixel values are generated by pixels that are directly adjacent to each other. ### Claim 9 A method for reducing spatial artifacts in multi-exposure images comprising: generating, with an image sensor comprising an array of color pixels arranged in rows and columns, first image pixel data corresponding to pixels having a first exposure time, and second image pixel data corresponding to pixels having a second exposure time, wherein the first exposure time is greater than the second exposure time; wherein the pixels used to generate the first and second image pixel data have the same spatial locations within the array; wherein the first and second image pixel data comprise a value representing light intensity; identifying whether the value is one of a valid or an invalid image pixel data; generating a ratio utilizing the valid image pixel data; wherein: the ratio comprises a first individual pixel value divided by a second individual pixel value; the first individual pixel value corresponds to a first color; the second individual pixel value corresponds to a second color that is different from the first color; and the first and second individual pixel values have a same exposure time; normalizing the computed ratio utilizing an ideal ratio, wherein the ideal ratio is the first exposure time divided by the second exposure time, and modifying the second image pixel data using the normalized ratio. ### Claim 10 (depends on 9) The method of claim 9, wherein the value is invalid if the value is greater than a first predetermined threshold. ### Claim 11 (depends on 10) The method of claim 10, wherein the value is invalid if the value is less than a second predetermined threshold. ### Claim 12 (depends on 9) The method of claim 9, wherein the value is valid if the value is between a first predetermined threshold and a second predetermined threshold. ### Claim 13 (depends on 9) The method of claim 9, wherein the image signal processor further identifies the valid image pixel data within a neighborhood of each identified invalid image pixel data. ### Claim 14 (depends on 13) The method of claim 13, wherein the image signal processor computes a representative value for the valid image pixel within a neighborhood of the invalid pixel and replacing the invalid pixel value with the average pixel value. ### Claim 15 (depends on 9) The method of claim 9, further comprising a color filter array disposed over the array of pixels, wherein the color filter array comprises the first color and the second color. ### Claim 16 (depends on 9) The method of claim 9, wherein the first and second individual pixel values are generated by pixels that share at least one of: a same row and a same column. ### Claim 17 (depends on 9) The method of claim 9, wherein the first and second individual pixel values are generated by pixels that are directly adjacent to each other. ### Claim 18 A system for producing flicker-free images of a scene illuminated by a light using an alternating current source, comprising: an image sensor, comprising: a color filter array comprising a plurality of color filters situated on an array of pixels arranged in rows and columns, wherein the image sensor obtains: first image pixel data corresponding to pixels having a first exposure time, and second image pixel data corresponding to pixels having a second exposure time; wherein the first exposure time is greater than the second exposure time; wherein the pixels used to generate the first and second image pixel data have the same spatial locations within the array; a storage unit coupled to the image sensor, wherein the storage unit stores the first and second image pixel data; an image signal processor coupled to the storage unit, wherein the image signal processor: identifies valid and invalid image pixel data based on a pixel data value; generates a color ratio utilizing the valid image pixel data; wherein: the ratio comprises a first individual pixel value divided by a second individual pixel value; the first individual pixel value corresponds to a first color from the plurality of color filters; the second individual pixel value corresponds to a second color from the plurality of color filters that is different from the first color; and the first and second individual pixel values have a same exposure time; normalizes the color ratio utilizing an ideal ratio, wherein the ideal ratio is the first exposure time divided by the second exposure time; modifies the second image pixel data using the normalized color ratio to form corrected image pixel data; and combines the corrected image pixel data with the first image pixel data to form a multi-pixel data image; and an I/O device for displaying the multi-pixel data image. ### Claim 19 (depends on 18) The system according to claim 18, wherein the first and second individual pixel values are generated by pixels that share at least one of: a same row and a same column. ### Claim 20 (depends on 18) The system according to claim 18, wherein the first and second individual pixel values are generated by pixels that are directly adjacent to each other.