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Packed Lempel-Ziv-Welch Compression

IP.com Disclosure Number: IPCOM000033724D
Publication Date: 2004-Dec-23

Publishing Venue

The IP.com Prior Art Database

Abstract

The LZW algorithm produces a series of tokens T that are integers within the range 0 to N, where N is a known variable. Traditionally the tokens are packed into a bit stream by writing B bits, where B is the smallest integer such that 2B ³ N. With additional logic, it is possible to improve the packing efficiency and save approximately a half a bit per code. The lowest significant bits (LSBs) of the token T are examined. If a one in the most significant bit (MSB) would result in a token larger than N, then this bit is extraneous, and may be omitted from the bit stream.