Method and apparatus for compressing and decompressing image dat

Details Method and apparatus for compressing and decompressing image dat Method and apparatus for compressing and decompressing image dat

1995-08-22

1997-11-18

Hoff, Marc S.

Coded data generation or conversion

Digital code to digital code converters

To or from bit count codes

341 51, H03M 746

Patent

active

056892551

ABSTRACT:
Image data such as text or half-tone images is compressed and decompressed. A compressor has three phases: a bit-run length phase that counts the length of each run of consecutive identical pixels; a pairs-repetition phase that compresses repeated pairs of pixel run values to one copy of the repeated pair and a repeat count; and an optional dictionary-based micro-table encoder. The micro-table, which may be used in any application calling for a least recently used (LRU) mechanism, has multiple qualification layers, with elements within a qualification layer being promoted to the next higher qualification layer upon the occurrence of a table hit for that element, and being demoted to the next lower qualification layer by being bumped by elements promoted up from below. The result is a table that is weighted both by frequency and recency of hits.

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Internet Article, Newsgroup Comp.Compression.Research FAQ, Subjects 7,8,16,70. Can be Retrieved at HTTP://WWW.LIB.OX.AC.UK/INTERNET/NEWS/FAQ/COMP.COMPRESSION.RESEARCH.HTML (no date).

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