Patent ID: 7057770
Filing Date: 2006-06-06
Classification: H04N

Abstract:
1. A method for compressing and decompressing a digital halftone monochrome bitmap comprising the steps of: (a) obtaining an input digital halftone monochrome bitmap of dimensions in pixels high and wide such that a plurality of equal-sized multi-pixel halftone cells are wholly contained, (b) reducing the possible patterns of monochrome pixels within said halftone cells by shifting certain pixels either horizontally or vertically according to a master grid based on a checkerboard pattern, (c) parsing said revised halftone cells into individual files, one each for each pixel position within the cell, (d) recombining said files into a single file, (e) encoding said single file's alternating runs of two monochrome colors with variable-length binary numbers within which all but one binary permutation may designate the length of the run and a return to start, and one binary permutation designates none of the contained run-lengths and to move on to larger successive binary numbers, (f) generating the increasing sizes of said successive run-length-containing variable-length binary numbers by a plurality of means, including Fibonacci numbers, byte-length-based numbers, or other means based on efficiency, (g) generating a compressed file of fewer bits than the input bitmap by utilizing steps (a)-(f), (h) reversing said method in steps (b)-(g) until said compressed file is uncompressed to replicate the said reduced pattern bitmap, (i) displaying said bitmap on a computer printer or monitor.