Patents Examined by Ra Huynh
  • Patent number: 6518981
    Abstract: To generate a color palette having m colors (such as 28=256 colors) from a color image described in a color space, pixel image data corresponding to the color image is first obtained. A frequency of occurrence for each color in the pixel image data is then determined. Each color in the pixel image data is assigned to one of a predetermined number of cells into which the color space has been partitioned, the predetermined number being not greater than m. The most commonly occurring color is selected in each cell in which a color exists, so as to obtain n palette colors. A vote value is calculated for each unselected color, the vote value being based at least in part on the frequency of occurrence of the color in the pixel image and a weighting factor based on a rank of the color in its corresponding cell, the unselected colors being the colors not selected in the first selecting step. Thereafter, m-n colors are selected as the unselected colors with the highest vote values.
    Type: Grant
    Filed: November 12, 1997
    Date of Patent: February 11, 2003
    Assignee: Canon Kabushiki Kaisha
    Inventors: Jun Zhao, Timothy L. Kohler, Jonathan Hui