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Re: Free way to decompress LZW archives?

On Sat, 28 Jul 2001, Junichi Uekawa wrote:

>John Galt <galt@inconnu.isu.edu> immo vero scripsit
>> Debian needs permission to modify as well.  There has been a substantial
>> non-interest in .LZW decompressors since the Unisys thing in '94, so I
>> doubt that lha would be put in main
>Please tell me what a .LZW decompressor is.
>I thought gunzip could decompress such thing which
>was generated by "compress" command.

LZW decompressor is the same as a .Z decompressor: decompress.  Gunzip
can do UNIX Compress.  How it gets around the Sperry patent (4,558,302)
yet a .GIF doesn't is beyond me.

>However my impression is that lha compresses using a combination of the LZSS
>and Huffman encoding, which I believe is not LZW.

LZSS is based on LZ77, so has one of two dates of origination: either 1977
or 1982.  It looks as if Storer and Szymanski never patented it, so it
came out of patent in 1997.  LZSS IS LZ77 and Huffman, BTW, and Huffman
came out of patent in the seventies.

>However, reading the source code gives me an impression that
>they might be doing something similar to LZW, but I am no longer quite
>sure of details.

Probably not, LZW is based on LZ78.

>	junichi

<a mailto:galt@inconnu.isu.edu>Who is John Galt?</a>

Failure is not an option. It comes bundled with your Microsoft product.
	-- Ferenc Mantfeld

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