DEFLATE (algorithm)

From Free net encyclopedia

DEFLATE is a lossless data compression algorithm that uses a combination of the LZ77 algorithm and Huffman coding. It was originally defined by Phil Katz for version 2 of his PKZIP archiving tool, and was later specified in RFC 1951.

DEFLATE is widely thought to be free of any subsisting patents, and at a time before the patent on LZW (which is used in the GIF file format) expired, this has led to its use in gzip compressed files and PNG image files, in addition to the ZIP file format for which Katz originally designed it.

Source code for DEFLATE compression and decompression can be found in zlib, the freely-available, general-purpose compression library.

A higher compression ratio version of DEFLATE is implemented by 7-Zip. AdvanceCOMP also uses this implementation, which allows recompression of Gzip, PNG, MNG and ZIP files to obtain smaller filesizes than with zlib. An even more effective (but also more user-input demanding) DEFLATE routine is employed by Ken Silverman's KZIP and PNGOUT.

[edit]