METHOD AND APPARATUS FOR QUANTIZING A COLOR IMAGE THROUGH A SINGLE DITHER MATRIX

摘要

This invention relates to a color image dithering method and apparatus for producing an output point (Fig. 12, 41) in an output color space (42) corresponding to a selected vertex (V, 0, 0, 0) in a tetrahedron of a three-dimensional cubic subinterval (40) of a pixel point in a source color space (42). The device includes a truncating logic (Fig. 11, 182) for truncating a value of a pixel having a point in a color space of the source image, for locating a three-dimensional cubic subinterval containing the point (41); a random number generator (184) for generating a random number as a threshold value for dithering each pixel value of the source image; a first comparator (186) for locating a tetrahedron having four vertices in the three-dimensional cubic subinterval that contains the pixel point; a second logic (188) for assigning a probability density corresponding to each of the vertex; a second comparator (190) for selecting a vertex provided by the threshold value through an inverse probability distribution function derived from the probability densities of said vertices; and a third logic (192) for locating an output point in an output color space corresponding to the selected vertex.