Filter
Top Products
Copyrights and Legal Notices
31
The authors make NO WARRANTY or representation, either express or implied, with respect to this software, its
quality, accuracy, merchantability, or fitness for a particular purpose. This software is provided "AS IS", and you, its
user, assume the entire risk as to its quality and accuracy.
This software is copyright (C) 1991-2010, Thomas G. Lane, Guido Vollbeding.
All Rights Reserved except as specified below.
Permission is hereby granted to use, copy, modify, and distribute this software (or portions thereof) for any purpose,
without fee, subject to these conditions:
1. If any part of the source code for this software is distributed, then this README file must be included, with
this copyright and no-warranty notice unaltered; and any additions, deletions, or changes to the original files
must be clearly indicated in accompanying documentation.
2. If only executable code is distributed, then the accompanying documentation must state that "this software is
based in part on the work of the Independent JPEG Group".
3. Permission for use of this software is granted only if the user accepts full responsibility for any undesirable
consequences; the authors accept NO LIABILITY for damages of any kind.
These conditions apply to any software derived from or based on the IJG code, not just to the unmodified library. If
you use our work, you ought to acknowledge us.
Permission is NOT granted for the use of any IJG author's name or company name in advertising or publicity relating
to this software or products derived from it. This software may be referred to only as "the Independent JPEG Group's
software".
We specifically permit and encourage the use of this software as the basis of commercial products, provided that all
warranty or liability claims are assumed by the product vendor.
ansi2knr.c is included in this distribution by permission of L. Peter Deutsch, sole proprietor of its copyright holder,
Aladdin Enterprises of Menlo Park, CA.ansi2knr.c is NOT covered by the above copyright and conditions, but instead
by the usual distribution terms of the Free Software Foundation; principally, that you must include source code if you
redistribute it. (See the file ansi2knr.c for full details.) However, since ansi2knr.c is not needed as part of any program
generated from the IJG code, this does not limit you more than the foregoing paragraphs do.
The Unix configuration script "configure" was produced with GNU Autoconf. It is copyright by the Free Software
Foundation but is freely distributable. The same holds for its supporting scripts (config.guess, config.sub, ltmain.sh).
Another support script, install-sh, is copyright by X Consortium but is also freely distributable.
The IJG distribution formerly included code to read and write GIF files. To avoid entanglement with the Unisys LZW
patent, GIF reading support has been removed altogether, and the GIF writer has been simplified to produce
"uncompressed GIFs". This technique does not use the LZW algorithm; the resulting GIF files are larger than usual,
but are readable by all standard GIF decoders.
We are required to state that "The Graphics Interchange Format(c) is the Copyright property of CompuServe
Incorporated. GIF(sm) is a Service Mark property of CompuServe Incorporated."
REFERENCES
We recommend reading one or more of these references before trying to understand the innards of the JPEG
software.
The best short technical introduction to the JPEG compression algorithm is Wallace, Gregory K. "The JPEG Still
Picture Compression Standard", Communications of the ACM, April 1991 (vol. 34 no. 4), pp. 30-44. (Adjacent articles
in that issue discuss MPEG motion picture compression, applications of JPEG, and related topics.) If you don't have
the CACM issue handy, a PostScript file containing a revised version of Wallace's article is available at
http://www.ijg.org/files/wallace.ps.gz. The file (actually a preprint for an article that appeared in IEEE Trans.
Consumer Electronics) omits the sample images that appeared in CACM, but it includes corrections and some added
material. Note: the Wallace article is copyright ACM and IEEE, and it may not be used for commercial purposes.
A somewhat less technical, more leisurely introduction to JPEG can be found in "The Data Compression Book" by
Mark Nelson and Jean-loup Gailly, published by M&T Books (New York), 2nd ed. 1996, ISBN 1-55851-434-1. This
book provides good explanations and example C code for a multitude of compression methods including JPEG. It is
an excellent source if you are comfortable reading C code but don't know much about data compression in general.
The book's JPEG sample code is far from industrial-strength, but when you are ready to look at a full implementation,
you've got one here.