LZW DATA COMPRESSION TECHNIQUE

LZW DATA COMPRESSION TECHNIQUE

ABSTRACT

Any programmer working on mini or microcomputers in this day and age should have at least some exposure to the concept of data compression. In MS-DOS world, programs like ARC, by System Enhancement Associates, and PKZIP, by Pkware are ubiquitous. ARC has also been ported to quite a few other machines, running UNIX, CP/M, and so on. CP/M users have long had SQ and USQ to squeeze and expand programs. Unix users have the COMPRESS and COMPACT utilities. Yet the data compression techniques used in these programs typically only show up in two places: file transfers over phone lines, and archival storage.
Data compression has an undeserved reputation for being difficult to master, hard to implement, and tough to maintain. In fact, the techniques used in the previously mentioned programs are relatively simple, and can be implemented with standard utilities taking only a few lines of code. This report discusses a good all-purpose data compression technique: Lempel-Ziv-Welch, or LZW compression.