A tutorial by Martin Zolnieryk on LZW, along with some pseudo code and links.

http://www.starsdev.com/developer/lzw.php

An article that describes itself as showing how to implement LZW compression in MFC.

http://codeproject.com/cpp/LZWCompression.asp

by Ziv and Lempel. The seminal LZ78 paper which spawned LZW, GIF, and an entire academic industry.

Update 2004: Document is now packed in RAR format.

http://www.compression.ru/download/articles/lz/ziv_lempel_1978_variable-rate_pdf.rar

Tom Cagill creates GIF files without using LZW.

http://www.ddj.com/documents/s=1486/ddj0110o/

GAO Research sells modem software for quite a few different platforms, including a big batch of DSP parts. Naturally, this includes modules to perform both V.42bis and V.44 data compression.

http://www.gaoresearch.com/products/modemsoftware/modemsoftware.php

A good description of LZW, along with some specific information about TIFF’s implemenation of this compression algorithm.

http://netghost.narod.ru/gff/graphics/book/ch09_04.htm

A lecture in German on LZ coding.

http://www.stud.uni-karlsruhe.de/~un55/lz_ToC.html

A Unisys press release explaining their beliefs regarding licensing required to use GIF technology in your products. As of this posting (8/2003) the US patents appear to have expired, but there are European and Japanese patents will not expire until some time in 2004.

http://www.unisys.com/about__unisys/lzw/

Drew Scott Daniels was attempting to find out when
all the LZW patents all over the world were
going to expire. This is not as easy as you might think!
Drew was kind enough to forward links to the message
boards where the question was posted. To follow the thread,
go to the bottom of the page and click on the Next
by thread link.

http://lists.debian.org/debian-legal/2003/debian-legal-200303/msg00526.html

Steven Pigeon’s Ph. D Thesis from the University of Montreal. Proposes a new set of universal codes, which he dubs taboo codes, as well as new optimization algorithms for (Start, Step, Stop) codes. Plus lossy variations on LZW.

http://www.iro.umontreal.ca/~pigeon/science/publications/phd.ps.zip

The National Insitute of Standards and Techology reference page on LZW compression. Pointers to an explanation, implementation, and more information.

http://www.nist.gov/dads/HTML/lempelZivWelch.html

David describes his work creating a bijective LZW compressor. (See this and other pages of David for details on what he means by bijective.) The page includes C++ source.

http://bijective.dogma.net/compreslzw1.htm

File and database compression components for Delphi. Compress to/from file, memory, and blob. Uses RLE, LZH, and LZW. Shareware.

Version 7.0 was released in September of 2002.

http://www.spis.co.nz/compress.htm

This thread reveals the actual dates for the LZW patent expiration, including US, European, and Japanese patents.

http://groups.google.com/groups?&threadm=a5aa8dd0.0208271613.3cd18da6%40posting.google.com

This is an open source PDF renderer, which includes code that decompresses LZW data embedded in the PDF file. It doesn’t actually do the LZW decompression itself - it converts the data to a format that can be handled by UNIX compress.

http://www.foolabs.com/xpdf/

This Java browswer knows how to render PDF files, which means it understands the elusive LZW compressed data format used by Adobe.

http://www.cs.berkeley.edu/~phelps/Multivalent/

A variety of libraries that can be used to read and write PDF format.

http://www.geocities.com/marcoschmidt.geo/java-document-libraries.html#pdf

An overview of the basics, including Shannon-Fano, Huffman, Arithmetic coding, and a section on LZW for good measure.

http://www.cs.cf.ac.uk/Dave/Multimedia/node207.html

Notes from an Information Theory course at MIT.

http://www-mtl.mit.edu/Courses/6.095/notes/LZW-examples.html

A guy named Steve Blackstock takes a shot at making this all clear to you. Gives some details on the LZW variation used in GIF files.

http://www.cis.udel.edu/%7Eamer/CISC651/lzw.and.gif.explained.html

D. T. Hoang, P. M. Long and J. S. Vitter. “Dictionary Selection using Partial Matching,” Information Sciences, 119(1-2), 57-72, 1999. This paper describes an attempt to squeeze improved compression out of existing dictionary-based schemes by using multiple context-based dictionaries for encoding.

http://www.cs.duke.edu/~jsv/Papers/catalog/node73.html

Class notes on lossless compression algorithms. Quick info on Huffman, Adaptive Huffman, and LZW.

http://www.cs.sfu.ca/CourseCentral/365/li/material/notes/Chap4/Chap4.1/Chap4.1.html

Cheok Yan Cheng decided to write up a short tutorial on LZW compression. It is presented here, along with some source code.

http://www.geocities.com/yccheok/lzw/lzw.html

The Wikipedia entry for LZW compression. Good overview with plenty of links.

http://en.wikipedia.org/wiki/LZW

Bill has some Java LZ78 code here, along with a few other links to compression info.

http://www2.hawaii.edu/~luoma/code.html

An LZW variant that has been adopted as a standard by the ECMA.

http://www.ecma.ch/ecma1/STAND/ECMA-151.HTM

A short (and incorrect) definiton of the acronym LZW from Computer Knowledge.

http://www.cknow.com/ckinfo/acronyms/lzw.htm

A page with a brief description of LZW compression by Dominik Szopa. This page includes a Java applet that helps show how LZW looks in action.

http://www.cs.sfu.ca/CC/365/li/squeeze/LZW.html

The definition of LZ78 from the Free On-line Dictionary of Computing.

http://burks.bton.ac.uk/burks/foldoc/0/68.htm

The definition of LZW from the Free On-line Dictionary of Computing.

http://burks.bton.ac.uk/burks/foldoc/59/64.htm