US 2006/0132811 A1Published application

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

AssigneeSkyward Optics LLC

InventorRobert Case

Life of this patent

Estimating the term…

Loading patent…

Abstract

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.

Claims1

Dependent claims

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-above contained run-lengths and to move on to a larger successive binary number.
(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 step e,
(h) reversing said method until said compressed file is uncompressed to replicate the said reduced pattern bitmap,
(i) displaying said bitmap on a computer printer or monitor.

6 more elements

Dependencies are inferred from the claim text.