COLOUR QUANTIZATION

Definition: The process of finding the best set of colours (palette) for representing an image. Two common methods are "median cut," which works best for real-world (scanned or photographed) images, and "popularity," which does well for drawn images. The popularity method simply picks the n colours used the most in the image. This tends to omit colours for highlights in photographs, which are important, although not the most popular. The median cut method assigns all available colours to groupings, then splits the groupings to determine a representative set of colours. The more bits available for each colour component, the more memory and time required to quantize, and the better colour matches that are obtained.