# US 7,609,882 B2 · Image compression and decompression method capable of encoding and decoding pixel data based on a color conversion method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,609,882 B2 - Document ID: US7609882B2 - Status: Granted - Kind: B2 - Application number: 10/908,773 - Filed: 2005-05-25 - Published: 2006-11-30 - Granted: 2009-10-27 - Earliest claimed: 2005-05-25 - Assignees: Himax Technologies Limited - Inventors: Kai-Ting Lee; Ling-Shiou Huang - Web page: https://patentgrep.com/patent/US7609882B2 ## CPC - H04N 1/64: Systems for the transmission or the storage of the colour picture signal; Details therefor, e.g. coding or decoding means therefor {(H04N19/00 takes precedence)} - H04N 19/132: Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking - H04N 19/182: the unit being a pixel - H04N 19/186: the unit being a colour or a chrominance component - H04N 19/50: using predictive coding (H04N19/61 takes precedence) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An image compression and decompression method encodes and decodes pixel data based on a color conversion method. Base on the relationships of corresponding color components of two adjacent pixels, the corresponding color components are encoded either by a white and black modification, a down-sampling or an edge modification. Based on the relationships of encoded color components of the two adjacent pixels, the corresponding encoded color components are decoded either by an inverse white and black modification, an up-sampling or an inverse edge modification. ## Claims ### Claim 1 A computer implemented method for encoding pixel data comprising: checking if a pixel and an adjacent pixel are either black or white; if one of the pixels is either black or white, performing a white and black modification on data of the pixels by equalizing red, green and blue components of the pixel which is either black or white; checking if a difference of a color component of the pixel and a same color component of the adjacent pixel is greater than a predetermined value; if the difference of the color components of the two adjacent pixels is not greater than the predetermined value, generating an average of the color components of the pixels and generating a pilot bit; and if the difference of the color components of the two adjacent pixels is greater than the predetermined value, removing least significant bits (LSBs) of data of the color components of the pixels and generating a pilot bit. ### Claim 2 (depends on 1) The computer implemented method of claim 1 further comprising converting data of the pixels to generate color components of the pixels. ### Claim 3 (depends on 1) The computer implemented method of claim 1 wherein performing a white and black modification on data of the pixels further comprises removing data of a color component of the pixel which is either black or white and retaining data of a corresponding color component of the adjacent pixel. ### Claim 4 A computer implemented method for encoding pixel data comprising: checking if a difference of corresponding color components of two adjacent pixels is greater than a predetermined value; if the difference of the color components of the two adjacent pixels is not greater than the predetermined value, down-sampling data of the color components of the pixels and generating a pilot bit corresponding to down-sampling; checking if the pixels are black or white one-by-one, and if the pixels contain a black or white pixel, performing a white and black modification on data of the pixels by equalizing red, green and blue components of the pixel which is either black or white. ### Claim 5 (depends on 4) The computer implemented method of claim 4 wherein performing a white and black modification on data of the pixels further comprises removing data of the color component of the pixel which is either black or white and retaining data of the corresponding color component of the adjacent pixel. ### Claim 6 (depends on 4) The computer implemented method of claim 4 further comprising converting data of the pixels to generate the color components of the pixels. ### Claim 7 (depends on 4) The computer implemented method of claim 4 wherein down-sampling data of the color components of the pixels is generating an average of the color components of the pixels. ### Claim 8 A computer implemented method for encoding pixel data comprising: checking if a difference of corresponding color components of a first pixel and a second pixel adjacent to the first pixel is greater than a predetermined value; if the difference of the color components of the first and second pixels is greater than the predetermined value, performing an edge modification by removing least significant bits (LSBs) of data of the color components of the pixels and generating a pilot bit corresponding to removing the LSBs; and checking if the pixels are black or white one-by-one, and if the pixels contain a black or white pixel, performing a white and black modification on data of the pixels by equalizing red, green and blue components of the pixel which is either black or white. ### Claim 9 (depends on 8) The computer implemented method of claim 8 wherein performing a white and black modification on data of the pixels further comprises removing data of the color component of the pixel which is either black or white and retaining data of the corresponding color component of the adjacent pixel. ### Claim 10 (depends on 8) The computer implemented method of claim 8 further comprising converting data of the pixels to generate the color components of the pixels. ### Claim 11 (depends on 8) The computer implemented method of claim 8 further comprising: checking if a difference of the corresponding color components of a third pixel adjacent to the second pixel, and a fourth pixel adjacent to the third pixel is greater than a second predetermined value; checking if a difference of the corresponding color components of the second pixel and the third pixel is greater than a third predetermined value; and if the difference of the color components of the first and second pixels is greater than the first predetermined value, the difference of the color components of the third and fourth pixels is not greater than the second predetermined value, and the difference of the color components of the second and third pixels is not greater than the third predetermined value, setting the color component of the second pixel to the corresponding color component of the third pixel. ### Claim 12 (depends on 11) The computer implemented method of claim 11 further comprising down-sampling data of the color components of the third and fourth pixels. ### Claim 13 (depends on 12) The computer implemented method of claim 12 wherein down sampling data of the color components of the third and fourth pixels is generating an average of the color components of the third and fourth pixels. ### Claim 14 The computer implemented method of 12 further comprising generating a pilot bit corresponding to down-sampling. ### Claim 15 (depends on 11) The computer implemented method of claim 11 wherein the first, second and third predetermined values are the same.