This topic encompasses the LZ78 algorithm and its descendant, LZW. LZ78 is one of two seminal compression algorithms developed in the late 1970s. LZW is best know as the core compennt of the GIF compression format.
Evince is a document viewer for the GNOME desktop environment. It currently supports pdf, postscript, djvu, tiff and dvi. The goal of evince is to replace the multiple document viewers that exist on the GNOME Desktop with a single simple application. Source code is available.
Created: 10/04/2008
by Maxim SmirnovMore...
This page describes Flexible Parsing, a proposed extension for dictionary based LZ compression schemes. Yossi Matias, Nasir Rajpoot, and Cenk Sahinalp have a summary of their work on this page, along with links to three PS format papers that go into detail on the results. The authors summarize this improved technique as "looking one step ahead for the longest phrase in the dictionary instead of trying to find the longest possible phrase at hand."
Created: 14/12/1999
by Mark NelsonMore...
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.
Created: 24/08/2003
by Mark NelsonMore...
This paper describes a few searching algorithms to be used on compressed files. An AC type algorithm for searching in Huffman encoded files, a KMP type algorithm for LZ derivatives and a BM type algorithm for searching in files compressed by Byte-Pair-Encoding (BPE). BPE gave results upto 3 times faster than those achieved by agrep.
Created: 12/06/2005
by Sachin GargMore...
This Java browswer knows how to render PDF files, which means it understands the elusive LZW compressed data format used by Adobe.
Created: 08/08/2002
by Mark NelsonMore...
TC is a freeware LZW-based file compressor. Low memory usage, fast compression and decompression speed, relatively good compression ratio. The site is on Russian, but Babel Fish gives a decent translation.
Created: 19/05/2005
by encodeMore...
A nice explanation of LZW compression from the fine folks at the Data Compression Center.
This link points to an archived site, as the original has disappeared. Links on the archived page may or may not work properly.
Created: 06/11/1999
by Mark NelsonMore...
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.
Created: 17/03/2003
by Mark NelsonMore...
Version 1.1 of the lossless data compression toolkit by Nico deVries. The C sources in this toolkit include an LZW compressor, AR002 archiver, a PPM like compressor using arithmetic compression, Huffman compressor, splay tree program, and LZRW1. Quite a variety.
Created: 14/11/1999
by Mark NelsonMore...
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.
Created: 08/04/2002
by Mark NelsonMore...
This page has links to the source code for a family of compressors written by Charles Bloom. This includes the LZP family, an LZW example, LZRW, and LZCB.
Created: 14/11/1999
by Mark NelsonMore...
This page is designed made to teach people about Lossless compression algorithms through the use of text graphics and Java Applets! Dominik Szopa has created pages that demonstrate Huffman, Adaptive Huffman, and LZW compression.
DCL reader SF has this to say: While the site itself is rather quick, it's disorganized...the Java applets really don't show what's going on at all. They show only the external effects...This site has definate potential, and I do recommend people see it. However, it's also got a ways to go yet. .
Created: 24/12/1998
by Mark NelsonMore...
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.
Created: 16/05/2004
by Mark NelsonMore...
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.
Created: 21/12/2003
by Mark NelsonMore...
A good description of LZW, along with some specific information about TIFF's implemenation of this compression algorithm.
Created: 09/11/2003
by Mark NelsonMore...
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.
Created: 26/04/2003
by Mark NelsonMore...
The National Insitute of Standards and Techology reference page on LZW compression. Pointers to an explanation, implementation, and more information.
Created: 17/03/2003
by Mark NelsonMore...
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.
Created: 27/12/2002
by Mark NelsonMore...
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.
Created: 15/09/2002
by Mark NelsonMore...
This thread reveals the actual dates for the LZW patent expiration, including US, European, and Japanese patents.
Created: 15/09/2002
by Mark NelsonMore...
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.
Created: 08/08/2002
by Mark NelsonMore...
An overview of the basics, including Shannon-Fano, Huffman, Arithmetic coding, and a section on LZW for good measure.
Created: 20/07/2002
by Mark NelsonMore...
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.
Created: 04/06/2002
by Mark NelsonMore...
Cheok Yan Cheng decided to write up a short tutorial on LZW compression. It is presented here, along with some source code.
Created: 25/02/2002
by Mark NelsonMore...
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.
Created: 22/11/1999
by Mark NelsonMore...
Short for Lempel-Zif-Welsh, a popular data compression technique developed in 1977 by J. Ziv and A Lempel, and later refined by T. Welsh. It is the compression algorithm used in the GIF graphics file format, which is one of the standard graphic formats used by CompuServe and the World Wide Web.
Created: 14/11/1999
by Mark NelsonMore...
Some information on LZW, it looks as though this has info on Licensing, but I'm not sure. All information is in Japanese.
Created: 09/11/1999
by Mark NelsonMore...
