Links to the PNG documentation in quite a few different formats.

http://www.libpng.org/pub/png/pngdocs.html

The comp.compression FAQ tells you the sad news about this problem.

http://www.faqs.org/faqs/compression-faq/part1/section-22.html

The comp.compression FAQ attempts to answer this for you.

http://www.faqs.org/faqs/compression-faq/part1/section-30.html

The comp.compression provides the Cliff Notes version of the question.

http://www.faqs.org/faqs/compression-faq/part2/section-1.html

Mostly history of how things have been going for support of PNG in the massive Mozilla project.

http://www.libpng.org/pub/png/pngmoz.html

The comp.compression FAQ can tell you exactly what it is.

http://www.faqs.org/faqs/compression-faq/part2/section-3.html

A freely redistributable lossless JPEG codec. Encoder, decoder, man pages, full C source, and some documentation.

ftp://ftp.cs.cornell.edu/pub/multimed/ljpg.tar.Z

A mirror site for the big compression software site. See 0index.txt for a list of what’s here, an unbelievably large treasure trove.

ftp://ftp.cs.tu-berlin.de/pub/msdos/mirrors/ftp.elf.stuba.sk/pc/pack

This ftp site has a few PPM programs, along with Bill Teahan’s thesis.

ftp://ftp.cs.waikato.ac.nz/pub/compression/ppm/

A very complete archive of compression programs, freeware, shareware, source, archviers, compressors, etc. They have it all. At last count this site has at least 1000 compression downloads

ftp://ftp.elf.stuba.sk/pub/pc/pack/

Public domain code by Daniel Bernstein. (Note that this ftp site has an excellent selection of compressoin programs and code.)

ftp://ftp.inria.fr/system/arch-compr/yabba.tar.Z

A huge collection of Swedish language text files

ftp://ftp.lysator.liu.se/pub/runeberg/src

An ftp site for compression software. This includes mirrors of some hard to find sites, such as those of D.J. Wheeler. Needs organization, and I often find it a bit slow from the US.

ftp://ftp.matsusaka-u.ac.jp/pub/compression/

by Keren O. Perlmutter, Sharon M. Perlmutter, Robert M. Gray, Richard A. Olshen, and Karen L. Oehler IEEE Transactions on Image Processing, February 1996). We investigate several VQ-based algorithms that seek to minimize both the distortion of compressed images and errors in classifying their pixel blocks.

ftp://isl.stanford.edu/pub/gray/reports/bayesvqip.ps

a copy of giflib

ftp://metalab.unc.edu/pub/Linux/libs/giflib/giflib-4.1.0.tar.gz

Hack Systems makes DataSafe, a product that backs up files using Zip format.

http://www.hacksystems.com

Xiaolin Wu’s static Huffman coding version of this program. Free of charge for research and non-commercial use. A total of 1.2 MBytes in a dozen or so files.

ftp://ftp.csd.uwo.ca/pub/from_wu/v.huff

A German language set of data compression links. A pretty good page of links, it probably doesn’t matter whether you speak German or not; the references mostly point to English language resources.

http://www.mathematik.uni-bielefeld.de/~bernhard/common/itlinks_fb.html

This page has references to a huge number of Wavelet-related research papers. I don’t know how many of them are online, but it is quite a treasure trove for the curious.

http://www.mathcad.com/products/we_pack.asp?page=3

The NeuQuant Neural-Net image quantization algorithm (© Anthony Dekker 1994) is a replacement for the common Median Cut algorithm. It is described in the article Kohonen neural networks for optimal colour quantization in Volume 5, pp 351-367 of the journal Network: Computation in Neural Systems (Institute of Physics Publishing, 1994).

http://www.ozemail.com.au/~dekker/NEUQUANT.HTML

A test version of zlib ported to the 3Com Pilot

http://www.pasta.cs.uit.no/~perm/PASTA/pilot/

An overview of the field by Debra A. Lelewer and Daniel S. Hirschberg. Lots of informative text. This appears to be a survey paper that was adapted for presentation on the web. Lossless compression techniques only!

http://www.ics.uci.edu/~dan/pubs/DataCompression.html

A nice description of Adaptive Huffman Coding, as seen through a couple of different algorithms. I believe this is part of a survey paper by Debra A. Lelewer and Daniel S. Hirschberg.

http://www.ics.uci.edu/~dan/pubs/DC-Sec4.html

http://lorenz.mur.csu.edu.au/complex/library/0Fractals.html

Home Page for Uzi Vishkin, of University of Maryland. Areas of research of interest in data compression include suffix trees and string matching.

http://www.umiacs.umd.edu/users/vishkin

Some information on LZW, it looks as though this has info on Licensing, but I’m not sure. All information is in Japanese.

http://www.unisys.co.jp/LZW/

Software implementing a complete DMC codec, plus code for a couple of different arithmetic encoders, and a linear time Huffman tree builder.

This program implements Dynamic Markov Compression (DMC) as described in
“Data Compression using Dynamic Markov Modelling”,
by Gordon Cormack and Nigel Horspool
in Computer Journal 30:6 (December 1987). The Guazzo arithmetic coder is used here.

http://plg2.math.uwaterloo.ca/~ftp/dmc/

Mr. Salomon is the author of Data Compression: The Complete Reference.

http://www.ecs.csun.edu/~dxs/

by David Salomon. This book is intended to provide an overview of the many different types of compression: it includes a taxonomy, an analysis of the most common systems of compression, discussion of their relative benefits and disadvantages, and their most common usages.

Please use
this link to purchase the book through Amazon.com. Your purchase will help support this web site.

http://www.ecs.csun.edu/~dsalomon/DC2advertis/DComp2Ad.html

Gordon is the author of DMC and many publications related to data compression. This is is home page, which has links to much of his work.

http://canola1.uwaterloo.ca/cormack/