ompression-related information

The FAQ and more pointers

• Jean-loup Gailly maintains the Frequently Asked Questions (FAQ) for the comp.compression and comp.compression.research newsgroups.
• Stuart Inglis maintains a large collection at http://www.internz.com/compression-pointers.html.
• Mark Nelson maintains a collection of his articles, source code, information on books, and other notes at http://web2.airmail.net/markn.
• This document describes the possible benefits in performance when compression of HTML files over a LAN connection and how it may interact with TCP slow start and delayed acknowledgement algorithms.  Öhttp://www.w3.org/Protocols/HTTP/Performance/Compression/LAN.html
• This document describes the possible benefits in performance when compressing HTML files over a PPP modem line http://www.w3.org/Protocols/HTTP/Performance/Compression/PPP.html

General-purpose compressors

• The implementation of arithmetic coding from the 1987 paper by Witten, Neal, and Cleary may be found via ftp://ftp.cpsc.ucalgary.ca/pub/projects/ar.cod/. A separate implementation of the same coding scheme can be found in The Data Compression Book by Nelson and Gailly. The code from Arithmetic coding revisited by Alistair Moffat, Radford Neal, and Ian H. Witten can be found on Moffat's page http://www.cs.mu.oz.au/~alistair.
• supports the Zip and UnZip programs, widely used on many platforms. http://www.cdrom.com/pub/infozip/ contains pointers to source code and documentation, and information about the authors.
• (GNU zip) was designed to replace compress. The compression library uses the same algorithm as Zip and gzip.
• Dr Ross's Compression Crypt contains Ross Williams' notes and sources for his work on various compression-related topics, including the LZRW family of algorithms.

Graphics compression

• Portable Network Graphics (PNG) is designed as a GIF successor, and uses the LZ77-variant found in gzip: http://www.cdrom.com/pub/png/.
• JPEG FAQ
• The documentation and software from Introduction to Information Theory and Data Compression may be obtained from http://www.dms.auburn.edu/compression. The Octave and Matlab scripts can be used to study JPEG-like schemes.

Fractal methods

• Yuval Fisher's page http://inls.ucsd.edu/Research/Fisher/Fractals contains a wealth of information and pointers to fractal methods. His Fractal Image Compresson contains a nicely-done introduction to the topic.
• The Waterloo Fractal Compression Project at http://links.uwaterloo.ca is another large page. Included is a pointer to the ``Waterloo BragZone'' which introduces a test suite and includes test results from various coders.
• The second edition of The Data Compression Book includes a chapter on fractal compression (by Jean-loup Gailly). On-line information is available through Nelson's page and http://www.teaser.fr/~jlgailly/.

Wavelets

• The Wavelet Digest at http://www.wavelet.org may be a good starting point. Colm Mulcahy's December 1996 Mathematics Magazine article contains an elementary introduction. A number of his papers, along with Matlab code and images, are available from http://www.spelman.edu/~colm.
• Some images in Information Theory and Data Compression were generated with Geoff Davis' Wavelet Image Compression Construction Kit, available through http://www.cs.dartmouth.edu/~gdavis.

Miscellaneous

• The GNU Project started in 1984 to develop a complete free Unix-like operating system. GNU zip (a general-purpose compressor) and Octave (a matrix language) are covered under the GNU General Public License. Information about the Free Software Foundation and the GNU Project is available through http://www.gnu.ai.mit.edu.
• The League for Programming Freedom (LPF) is an organization that opposes software patents and user-interface copyrights. The future of the LPF is uncertain (http://www.lpf.org is not currently available).
• A searchable database of patent information is available from the US Patent and Trademark Office via http://www.uspto.gov.