# US 7,609,302 B2 · Correction of non-uniform sensitivity in an image array > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,609,302 B2 - Document ID: US7609302B2 - Status: Granted - Kind: B2 - Application number: 10/915,454 - Filed: 2004-08-11 - Published: 2006-02-16 - Granted: 2009-10-27 - Earliest claimed: 2004-08-11 - Assignees: Micron Technology, Inc. - Inventors: Dmitri Jerdev; Igor Subbotin; Ilia Ovsiannikov - Web page: https://patentgrep.com/patent/US7609302B2 ## CPC - H04N 25/61: the noise originating only from the lens unit, e.g. flare, shading, vignetting or "cos4" - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An improved non-uniform sensitivity correction algorithm for use in an imager device (e.g., a CMOS APS). The algorithm provides zones having flexible boundaries which can be reconfigured depending upon the type of lens being used in a given application. Each pixel within each zone is multiplied by a correction factor dependent upon the particular zone while the pixel is being read out from the array. The amount of sensitivity adjustment required for a given pixel depends on the type of lens being used, and the same correction unit can be used with multiple lenses where the zone boundaries and the correction factors are adjusted for each lens. In addition, the algorithm makes adjustments to the zone boundaries based upon a misalignment between the centers of the lens being used and the APS array. ## Claims ### Claim 1 An imager device, comprising: a pixel array comprising a plurality of microlens for capturing images with more than one type of main lens for focusing light on the plurality of microlens; and a programmable sensitivity correction unit coupled to said pixel array for selectively correcting sensitivity of pixel signals from pixels in said pixel array by dividing said pixel array into an arrangement of zones, each zone having a plurality of pixels, and correcting the sensitivity of pixel signals from pixels in said pixel array according to their location within said zone, wherein said division of said pixel array and said sensitivity correction is performed according to the type of main lens used with said pixel array. ### Claim 2 (depends on 1) The imager device of claim 1 further comprising: a memory device coupled to said sensitivity correction unit for storing at least one correction value for correcting the sensitivity of pixel signals from of at least one corresponding pixel. ### Claim 3 (depends on 2) The imager device of claim 2, wherein said memory device comprises at least one register. ### Claim 4 (depends on 1) The imager device of claim 1 further comprising: a column bus coupling at least one pixel of said pixel array and said sensitivity correction unit. ### Claim 5 (depends on 4) The imager device of claim 4 further comprising: a sample and hold circuit coupled to said sensitivity correction unit for receiving corrected pixel signals; an analog-to-digital converter coupled to said sample and hold circuit for converting sampled corrected pixel signals to digital format; and a pixel processor for processing said digital corrected pixel signals. ### Claim 6 (depends on 1) The imager device of claim 1, wherein said sensitivity correction unit is configured to apply correction values to pixel signals for said pixels, each pixel in a given zone having a correction value determined according to at least one derivative calculation for each of said pixel signals. ### Claim 7 (depends on 1) The imager device of claim 1, wherein said arrangement of zones comprises a first number of zones when said pixel array is used with a first type of main lens, wherein each of said first number of zones respectively contains a predetermined plurality of pixels of said pixel array. ### Claim 8 (depends on 7) The imager device of claim 7, wherein: said arrangement of zones comprises a second number of zones different from said first number of zones when said pixel array is used with a second type of main lens different from said first type of main lens, and each of said second number of zones respectively contains a predetermined plurality of pixels of said pixel array different from said pixels associated with said first number of zones. ### Claim 9 (depends on 7) The imager device of claim 7, wherein said first number of zones comprises eight zones in the x-direction and eight zones in the y-direction. ### Claim 10 (depends on 1) The imager device of claim 1, wherein said sensitivity correction unit is configured to correct for any misalignment between respective centers of said pixel array and a main lens used with said pixel array. ### Claim 11 (depends on 1) The imager device of claim 1, wherein said imager device is incorporated onto an imager chip. ### Claim 12 (depends on 1) The imager device of claim 1, wherein said imager device comprises a CMOS imager. ### Claim 13 (depends on 1) The imager device of claim 1, wherein said imager device comprises a CCD imager. ### Claim 14 (depends on 1) The imager device of claim 1, wherein said sensitivity correction unit is configured to adjust a degree of correcting depending upon an amount of light received by said pixel array. ### Claim 15 An imager device, comprising: a pixel array comprising a plurality of microlenses; and a programmable sensitivity correction unit coupled to said pixel array for applying a correction factor for selectively correcting pixel signals of pixels in said pixel array by dividing said pixel array into an arrangement of zones, each zone having a plurality of pixels, and correcting the sensitivity of pixel signals from pixels in said pixel array according to their location within said zone, wherein said division of said pixel array and adjustment of said correction factor is performed according to a type of main lens used for focusing light on the plurality of microlenses. ### Claim 16 (depends on 15) The imager device of claim 15, wherein said programmable sensitivity correction unit is configured to multiply at least one correction factor by at least one pixel signal for at least one of said pixels. ### Claim 17 A method of correcting sensitivity of pixels of an imager device, the method comprising: determining which of a plurality of types of main lenses for focusing light on a plurality of microlenses, is being used with a pixel array comprising the plurality of microlenses; programming a sensitivity correction unit used with said pixel array to correspond to a first type of main lens being used with said pixel array, wherein said first type of lens is one of a plurality of types of main lenses for capturing images with said pixel array and said sensitivity correction unit; selectively correcting sensitivity of pixel signals from pixels in said pixel array according to said determined type of main lens by dividing said pixel array into an arrangement of zones, each zone having a plurality of pixels, and correcting the sensitivity of pixel signals from pixels in said pixel array according to their location within said zone, wherein said division of said pixel array is performed according to a type of main lens used with said pixel array, and wherein said sensitivity correction is adjusted according to a type of main lens used with said pixel array. ### Claim 18 (depends on 17) The method of claim 17 further comprising: forwarding at least one corrected pixel signal for at least one of said pixels to a sample and hold circuit; converting an output of said sample and hold circuit to digital format; and conducting further pixel processing of a digital version of said at least one corrected pixel signal. ### Claim 19 (depends on 17) The method of claim 17, wherein said act of determining comprises: determining that a first type of main lens, of a plurality of lenses for capturing images with said pixel array, is being used with said pixel array. ### Claim 20 (depends on 19) The method of claim 19, wherein said act of selectively correcting sensitivity comprises: dividing said pixel array into a predetermined first number of zones based upon said first type of main lens being used, where the pixel signals from pixels of each zone have a sensitivity correction determined according to at least one derivative calculation for pixel signals for said pixels. ### Claim 21 (depends on 20) The method of claim 20 further comprising: determining that a second type of main lens different from said first type of main lens, of said plurality of main lenses for capturing images with said pixel array, is being used with said pixel array; and dividing said pixel array into a predetermined second number of zones different from said first plurality of zones based upon said second type of main lens being used, where the pixel signals from pixels of each zone have a sensitivity correction determined according to at least one derivative calculation of said pixel signals. ### Claim 22 (depends on 17) The method of claim 17, wherein said act of programming comprises: assigning respective correction function values to each pixel of said pixel array, wherein said respective correction function values correspond to said first type of main lens. ### Claim 23 (depends on 22) The method of claim 22, wherein said act of assigning comprises: storing an initial correction function value corresponding to at least a first pixel of said pixel array; and storing a first derivative of said initial correction function value corresponding to a correction function value of at least a second pixel of said pixel array. ### Claim 24 (depends on 23) The method of claim 23 further comprising: storing a first derivative of said correction function value of said at least a second pixel corresponding to a correction function value of at least a third pixel of said pixel array; and storing a second derivative of said correction function value of said at least a second pixel corresponding to said correction function value of said at least a third pixel of said pixel array. ### Claim 25 (depends on 17) The method of claim 17, wherein said act of correcting further comprises: multiplying a first pixel value being read out from a first pixel of said pixel array by a first correction function value corresponding to said first pixel. ### Claim 26 (depends on 17) The method of claim 17, wherein said act of correcting further comprises: adjusting a degree of correcting depending upon an amount of light received by said pixel array. ### Claim 27 (depends on 20) The method of claim 20, wherein said act of dividing further comprises: determining that respective centers of said first type of main lens and said pixel array are misaligned; and adjusting respective boundaries of said first plurality of zones based on the misalignment of the centers of the first type of main lens and the pixel array. ### Claim 28 A method of correcting sensitivity of pixels of an imager device, the method comprising: determining which main lens, of a plurality of main lenses for capturing images with a given pixel array, is being used with said given pixel array and dividing said pixel array into an arrangement of zones according to the main lens being used; programming a sensitivity correction unit for correcting sensitivity of pixel signals from pixels in said pixel array and the main lens being used with the pixel array; reading out at least one pixel signal from a pixel array; applying a correction factor for selectively correcting sensitivity of said pixel signals from pixels in said pixel array; and wherein the pixel array comprising a plurality of microlenses; wherein the main lens is for focusing light on the plurality of microlenses. ### Claim 29 (depends on 28) The method of claim 28, wherein said act of applying comprises multiplying said correction factor by said at least one pixel signal. ### Claim 30 (depends on 28) The method of claim 28 wherein the applied correction factor depends on from which zone said pixel signal was read. ### Claim 31 A method of forming an imager device, the method comprising: coupling a programmable sensitivity correction unit to a pixel array comprising a plurality of microlenses for selectively correcting sensitivity of pixel signals from pixels in said pixel array, wherein said pixel signal sensitivity is adjusted according to a first zone arrangement corresponding to a first type of main lens used for focusing light onto the microlenses, and wherein said pixel signal sensitivity is adjusted according to a second zone arrangement corresponding to a second type of main lens used for focusing light onto the microlenses. ### Claim 32 (depends on 31) The method of claim 31 further comprising: coupling a storage device to said sensitivity correction unit for storing at least one correction value for correcting at least one pixel value. ### Claim 33 A semiconductor chip, comprising: a pixel array comprising a plurality of microlenses; and a programmable sensitivity correction unit coupled to said pixel array for selectively correcting sensitivity of pixel signals from pixels in said pixel array, wherein said pixel signal sensitivity correction is adjusted according to a first zone arrangement corresponding to a first type of main lens used for focusing light on the plurality of microlenses, and wherein said pixel signal sensitivity correction is adjusted according to a second zone arrangement corresponding to a second type of main lens used for focusing light on the plurality of microlenses. ### Claim 34 (depends on 33) The chip of claim 33 further comprising: a memory device coupled to said sensitivity correction unit for storing at least one correction value for correcting at least one corresponding pixel value. ### Claim 35 (depends on 34) The chip of claim 34, wherein said memory device comprises at least one register. ### Claim 36 (depends on 33) The chip of claim 33 further comprising: a column bus coupling at least one pixel of said pixel array and said sensitivity correction unit. ### Claim 37 (depends on 36) The chip of claim 36 further comprising: a sample and hold circuit coupled to said sensitivity correction unit for receiving corrected pixel signals for said pixels; an analog-to-digital converter coupled to said sample and hold circuit for converting sampled corrected pixel signals to digital format; and a pixel processor for processing said digital corrected pixel signals. ### Claim 38 (depends on 33) The chip of claim 33, wherein: said zone arrangement comprises a division of said pixel array into a plurality of zones containing more than one pixel; said sensitivity correction unit is configured to apply correction values to pixel signals for said pixels; and each pixel in a given zone requires a similar degree of sensitivity correction according to at least one derivative calculation of said pixel signals. ### Claim 39 (depends on 33) The chip of claim 33, wherein said zone arrangement comprises a first number of zones when said pixel array is used with a first type of main lens, wherein each of said first number of zones respectively contains a predetermined plurality of pixels of said pixel array. ### Claim 40 (depends on 39) The chip of claim 39, wherein: said zone arrangement comprises a second number of zones different from said first number of zones, when said pixel array is used with a second type of main lens different from said first type of main lens, and each of said second number of zones respectively contains a predetermined plurality of pixels of said pixel array different from said pixels associated with said first number of zones. ### Claim 41 (depends on 39) The chip of claim 39, wherein said first number of zones comprises eight zones in the x-direction and eight zones in the y-direction. ### Claim 42 (depends on 33) The chip of claim 33, wherein said sensitivity correction unit is configured to correct for any misalignment between respective centers of said pixel array and a main lens used with said pixel array. ### Claim 43 (depends on 33) The chip of claim 33, wherein said pixel array comprises a pixel array of a CMOS imager. ### Claim 44 (depends on 33) The chip of claim 33, wherein said pixel array comprises a pixel array of a CCD imager. ### Claim 45 A processor system, comprising: a processor; an imager device coupled to said processor, said imager device comprising: a pixel array comprising a plurality of microlenses; and a programmable sensitivity correction unit coupled to said pixel array for selectively correcting pixel signal sensitivity of pixels in said pixel array, wherein said pixel signal sensitivity correction is adjusted according to a first zone arrangement corresponding to a first type of main lens used for focusing light on the plurality of microlenses, and wherein said pixel signal sensitivity correction is adjusted according to a second zone arrangement corresponding to a second type of main lens used for focusing light on the plurality of microlenses. ### Claim 46 (depends on 45) The processor system of claim 45, wherein said imager device further comprises: a memory device coupled to said sensitivity correction unit for storing at least one correction value for correcting the sensitivity of at least one corresponding pixel value. ### Claim 47 (depends on 46) The processor system of claim 46, wherein said memory device comprises at least one register. ### Claim 48 (depends on 45) The processor system of claim 45, wherein said imager device further comprises: a column bus coupling at least one pixel of said pixel array and said sensitivity correction unit. ### Claim 49 (depends on 48) The processor system of claim 48, wherein said imager device further comprises: a sample and hold circuit coupled to said sensitivity correction unit for receiving corrected pixel signals for said pixels; an analog-to-digital converter coupled to said sample and hold circuit for converting sampled corrected pixel signals to digital format; and a pixel processor for processing said digital corrected pixel signals. ### Claim 50 (depends on 45) The processor system of claim 45, wherein: said zone arrangement comprises a division of said pixel array into a plurality of zones containing more than one pixel; and each pixel in a given zone has a correction value determined according to at least one derivative calculation for pixel signals for each of said pixels. ### Claim 51 (depends on 45) The processor system of claim 45, wherein said zone arrangement comprises a first number of zones when said pixel array is used with a first type of main lens, wherein each of said first number of zones respectively contains a predetermined plurality of pixels of said pixel array. ### Claim 52 (depends on 51) The processor system of claim 51, wherein: said zone arrangement comprises a second number of zones different from said first number of zones, when said pixel array is used with a second type of main lens different from said first type of main lens, and each of said second number of zones respectively contains a predetermined plurality of pixels of said pixel array different from said pixels associated with said first number of zones. ### Claim 53 (depends on 51) The processor system of claim 51, wherein said first number of zones comprises eight zones in the x-direction and eight zones in the y-direction. ### Claim 54 (depends on 45) The processor system of claim 45, wherein said sensitivity correction unit is configured to correct for any misalignment between respective centers of said pixel array and a main lens used with said pixel array. ### Claim 55 (depends on 45) The processor system of claim 45, wherein said imager device comprises a CMOS imager. ### Claim 56 (depends on 45) The processor system of claim 45, wherein said imager device comprises a CCD imager.