# US 8,787,653 B2 · Determining an orientation direction of a color edge at a pixel location in a color image > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,787,653 B2 - Document ID: US8787653B2 - Status: Granted - Kind: B2 - Application number: 13/426,203 - Filed: 2012-03-21 - Published: 2012-07-26 - Granted: 2014-07-22 - Earliest claimed: 2010-04-05 - Assignees: Xerox Corporation - Applicants: Xing Li; Meng Yao; Barbara L. Farrell - Inventors: Xing Li; Meng Yao; Barbara L. Farrell - Web page: https://patentgrep.com/patent/US8787653B2 ## CPC - H04N 1/58: Edge or detail enhancement; Noise or error suppression, e.g. colour misregistration correction (H04N1/62 takes precedence) - G06T 1/20: Processor architectures; Processor configuration, e.g. pipelining - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract What is disclosed is a system and method for determining an orientation direction of a color edge at a given pixel location in a binary color image. The orientation direction of the color edge is determined from eight pixel counts with each pixel count being a total number of pixels in each of eight regions of a window centered about a candidate pixel which resides along the color edge. The eight regions are associated with 8 compass points. The orientation of the edge is determined by a 1st, 2nd and 3rd tier control bits which are based upon the pixel counts of each region. The 1st, 2nd and 3rd tier control bits collectively form a 3-bit word. The 3-bit word defines the orientation direction. The teachings hereof provide an efficient way of performing binary edge orientation detection by making uses of intermediate results to simultaneously encode the edge orientation. ## Claims ### Claim 1 A circuit for determining an orientation direction of a color edge at a pixel location in a color image, said system comprising: a first tier of circuitry receiving, as input, eight pixel counts each comprising a total number of pixels of a color in a region of a window centered on a selected pixel in a bitmap of a halftoned color image, said first tier circuit generating, as output, four largest pixel counts of said eight input pixel counts and four 1st tier control bits used to select said four largest pixel counts; a second tier of circuitry receiving, as input, said four 1st tier control bits and said four largest pixel counts, said second tier circuit generating, as output, two 2nd tier control bits used to select two of the highest pixel counts of said four largest pixel counts, and to select two of said four 1st tier control bits; and a third tier of circuitry receiving, as input, said two selected highest pixel counts, two of said selected 1st tier control bits, and two of said selected 2nd tier control bits, said third tier of circuitry generating, as output, a 3rd tier control bit used to select one of said two selected 1st tier control bits, one of said two 2nd tier control bits, and a maximum pixel count of said two highest pixel counts, said selected 1st, 2nd and 3rd tier control bits comprising a 3-bit word which defines an orientation direction of said color edge. ### Claim 2 (depends on 1) The circuit of claim 1, wherein said first tier circuit comprises four comparators and four multiplexors, each comparator comparing two of said eight total pixel counts, each comparator generating, as a result of said comparison, a 1st tier control bit used to select a larger of two pixel counts using one of said multiplexors. ### Claim 3 (depends on 1) The circuit of claim 1, wherein said second tier circuit comprises two comparators and four multiplexors, each comparator comparing two of said four input pixel counts selected by said first tier circuit, each comparator generating, as a result of said comparison, a 2nd tier control bit used to select a highest of said two input larger pixel counts using a first two of said multiplexors and to select two of said four 1st tier control bits using a second two of said multiplexors. ### Claim 4 (depends on 1) The circuit of claim 1, wherein said third tier circuit comprises a comparator and two multiplexors, said comparator comparing two of said highest pixels counts selected by said second tier circuit, said comparator generating, as a result of said comparison, a 3rd tier control bit used to select a maximum pixel count for all of said regions, and to select one of said two selected 1st tier control bits, and one of said two selected 2nd tier control bits. ### Claim 5 (depends on 1) The system of claim 1, wherein said orientation directions associated with said 3-bit word comprises: ‘000’=N, ‘001’=S, ‘010’=W, ‘011’=E, ‘100’=NW, ‘101’=SE, ‘110’=SW, and ‘111’=NE. ### Claim 6 A computer implemented method for determining an orientation direction of a color edge at a pixel location in a color image, the method comprising: receiving a plurality of pixel counts, each pixel count comprising a total number of pixels of a color in a region of a window centered on a selected pixel in a bitmap of a color image, each of said regions being associated with an orientation direction relative to said selected pixel; comparing each of said pixel counts for each of said regions to determine a maximum pixel count, a result of each of said comparisons producing a 1st, 2nd and 3rd tier control bit; and forming a 3-bit word using said 1st, 2nd and 3rd tier control bits, said 3-bit word defining an orientation direction of a color edge wherein said selected pixel resides. ### Claim 7 (depends on 6) The computer implemented method of claim 6, wherein each of said regions has a unique orientation directions comprising: {N, E, S, W, NE, SW, NW, SE}. ### Claim 8 (depends on 6) The computer implemented method of claim 6, wherein comparing each of said pixel counts for each of said regions comprises: comparing pixel counts for each of four pairs of regions, each of said comparison generating a 1st tier control bit used to select a largest pixel count for each compared pair; comparing said four largest pixel counts, a result of each comparison producing a 2nd tier control bit used to select a highest pixel count for each pair; and comparing said two highest pixel counts together, a result of said comparison producing a 3rd tier control bit used to select a maximum pixel count of all of said received plurality of pixel counts. ### Claim 9 (depends on 8) The computer implemented method of claim 8, further comprising: using each of said two 2nd tier control bits to select two of said four 1st tier control bits; and using said 3rd tier control bit to select one of said two 1st tier control bits and one of said two 2nd tier control bits. ### Claim 10 (depends on 8) The computer implemented method of claim 8, wherein each of said four pairs of regions have orientation directions that are diametrically opposed comprising: , , , and . ### Claim 11 (depends on 6) The computer implemented method of claim 6, wherein said 3-bit word defining said orientation directions comprises: ‘000’=N, ‘001’=S, ‘010’=W, ‘011’=E, ‘100’=NW, ‘101’=SE, ‘110’=SW, and ‘111’=NE. ### Claim 12 A system for determining an orientation direction of a color edge at a pixel location in a color image, the system comprising: a memory; a storage medium for storing data; and a processor in communication with said memory and said storage medium, said processor executing machine readable instructions for performing: receiving a plurality of pixel counts, each pixel count comprising a total number of pixels of a color in a region of a window centered on a selected pixel in a bitmap of a color image, each of said regions being associated with an orientation direction relative to said selected pixel; comparing pixel counts for each of four pairs of regions, a result of each comparison producing a 1st tier control bit used to select a largest pixel count for each pair; comparing said four largest pixel counts, a result of each comparison producing a 2nd tier control bit used to select a highest pixel count for each pair; comparing said two highest pixel counts together, a result of said comparison producing a 3rd tier control bit; using each of said two 2nd tier control bits to select two of said four 1st tier control bits; using said 3rd tier control bit to select one of said two 1st tier control bits; using said 3rd tier control bit to select one of said two 2nd tier control bits; and using said selected 1st, 2nd and 3rd tier control bits to form a 3-bit word which defines the orientation direction for said color edge. ### Claim 13 (depends on 12) The system of claim 12, wherein each of said eight regions has a unique orientation directions obtained from the set comprising: {N, E, S, W, NE, SW, NW, SE}. ### Claim 14 (depends on 13) The system of claim 13, wherein each of said four pairs of regions have orientation directions that are diametrically opposed, comprising: , , , and . ### Claim 15 (depends on 12) The system of claim 12, wherein said 3-bit word defining said orientation directions comprises: ‘000’=N, ‘001’=S, ‘010’=W, ‘011’=E, ‘100’=NW, ‘101’=SE, ‘110’=SW, and ‘111’=NE.