DATA COMPRESSION SYSTEM AND TECHNIQUE

Methods and apparatus, including computer program products, are used to compress a true color image in such a way that the compressed image may be decompressed by a decompression method according to a dictionary-based compression technique. A color table defines a mapping from true colors to index color values. A set of zero or more candidate strings for a current pixel in the image is identified in a compression dictionary. Each candidate string corresponds to a string of pixels in the image, with the last pixel of the string corresponding to the current pixel. Each candidate string approximately matches the corresponding image pixel string. If the set of candidate strings for the current pixel is empty, one of the candidate strings for the previous current pixel is selected, and a code for the selected string is added to a compressed representation of the image.