Abstract: A method and apparatus for performing color compression uses human factors to weight a distance metric in order to select a set of k presentation colors to represent n colors in an original image, where n>k. This same distance metric is used as part of a process to select an optimal mapping of the original image pixels to the presentation colors. The presentation colors are selected based upon a data clustering scheme in which clusters of colors are selected based upon their respective distance from each color within a given cluster and from colors in other clusters. Colors in different clusters are required to be farther apart than colors in the same clusters. This accounts for colors with high importance in accurately presenting the presentation image but having low overall occurrence in the image file.

Abstract: A raster scan display system of the type which includes an anti-aliasing circuit for controlling the pixel brightness to remove the stair-step effect common to raster scan displays, wherein the improvement comprises gamma correction means supplied with the anti-aliased display data for correcting for non-linearity in the relationship between the pixel intensity data and the actual intensity of the corresponding pixel of the raster scan display.