None-of-the-above digital halftone compression and decompression

摘要

An improved method of encoding and compressing digital halftones that utilizes a "none-of-the-above" method for designating variable-length runs. A monochrome input bitmap is rearranged slightly to reduce the patterns possible in contained digital halftone cells. This revised monochrome bitmap is parsed into subfiles to optimize run-lengths. The parsed subfiles are combined into a single file whose alternating runs of 1's and 0's are converted into successive variable-length binary numbers. One of the permutations of an antecedent binary is designated "none-of-the-above" and its use triggers a subsequent variable-length binary. All other permutations within each variable-length binary may designate a specific contained run-length and such use triggers a return to the initial binary in the series. The above method is reversed to decode and uncompress the encoded file to reproduce the original revised monochrome bitmap for display by a computer monitor or printer.