Abstract: A code parser decodes coded compressed image information into an intermediate code. A code expander operating asynchronously relative to the code parser decompresses the compressed image information in accordance with such decoded information. A window register in the code parser has a length at least as long as the longest code in the intermediate code. When the intermediate code indicates a pattern in one line in a raster scan of an image corresponding to a pattern in an immediately preceding line, the window register and associated circuitry scan the one line and provide for the decompression in such line in accordance with the decompression at the corresponding positions in the preceding line. Such associated circuitry may include two memories, one for even scan lines and the other for odd scan lines. Alternate ones of the memories are activated for information comparison between adjacent lines during alternate line scans.