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Documentación de ayuda de Polycom CMA Desktop
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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.
The best currently available description of JPEG is the textbook "JPEG Still Image Data Compression Standard" by
William B. Pennebaker and Joan L. Mitchell, published by Van Nostrand Reinhold, 1993, ISBN 0-442-01272-1. Price
US$59.95, 638 pp. The book includes the complete text of the ISO JPEG standards (DIS 10918-1 and draft DIS
10918-2).
Although this is by far the most detailed and comprehensive exposition of JPEG publicly available, we point out that it
is still missing an explanation of the most essential properties and algorithms of the underlying DCT technology. If
you think that you know about DCT-based JPEG after reading this book, then you are in delusion. The real
fundamentals and corresponding potential of DCT-based JPEG are not publicly known so far, and that is the reason
for all the mistaken developments taking place in the image coding domain.
The original JPEG standard is divided into two parts, Part 1 being the actual specification, while Part 2 covers
compliance testing methods. Part 1 is titled "Digital Compression and Coding of Continuous-tone Still Images, Part 1:
Requirements and guidelines" and has document numbers ISO/IEC IS 10918-1, ITU-T T.81. Part 2 is titled "Digital
Compression and Coding of Continuous-tone Still Images, Part 2: Compliance testing" and has document numbers
ISO/IEC IS 10918-2, ITU-T T.83.
IJG JPEG 8 introduces an implementation of the JPEG SmartScale extension which is specified in a contributed
document at ITU and ISO with title "ITU-T JPEG-Plus Proposal for Extending ITU-T T.81 for Advanced Image
Coding", April 2006, Geneva, Switzerland. The latest version of the document is Revision 3.
The JPEG standard does not specify all details of an interchangeable file format. For the omitted details we follow
the "JFIF" conventions, revision 1.02. JFIF 1.02 has been adopted as an Ecma International Technical Report and
thus received a formal publication status. It is available as a free download in PDF format from http://www.ecma-
international.org/publications/techreports/E-TR-098.htm.
A PostScript version of the JFIF document is available at
http://www.ijg.org/files/jfif.ps.gz. There is also a plain text version at http://www.ijg.org/files/jfif.txt.gz, but it is missing
the figures.
The TIFF 6.0 file format specification can be obtained by FTP from ftp://ftp.sgi.com/graphics/tiff/TIFF6.ps.gz. The
JPEG incorporation scheme found in the TIFF 6.0 spec of 3-June-92 has a number of serious problems.
IJG does not recommend use of the TIFF 6.0 design (TIFF Compression tag 6). Instead, we recommend the JPEG
design proposed by TIFF Technical Note #2 (Compression tag 7). Copies of this Note can be obtained from
http://www.ijg.org/files/. It is expected that the next revision of the TIFF spec will replace the 6.0 JPEG design with
the Note's design. Although IJG's own code does not support TIFF/JPEG, the free libtiff library uses our library to
implement TIFF/JPEG per the Note.
ARCHIVE LOCATIONS
The "official" archive site for this software is www.ijg.org. The most recent released version can always be found
there in directory "files". This particular version will be archived as http://www.ijg.org/files/jpegsrc.v8b.tar.gz, and in
Windows-compatible "zip" archive format as http://www.ijg.org/files/jpegsr8b.zip.
The JPEG FAQ (Frequently Asked Questions) article is a source of some general information about JPEG.
It is available on the World Wide Web at http://www.faqs.org/faqs/jpeg-faq/ and other news.answers archive sites,
including the official news.answers archive at rtfm.mit.edu: ftp://rtfm.mit.edu/pub/usenet/news.answers/jpeg-faq/.
If you don't have Web or FTP access, send e-mail to mail-server@rtfm.mit.edu with body
send usenet/news.answers/jpeg-faq/part1
send usenet/news.answers/jpeg-faq/part2
ACKNOWLEDGMENTS
Thank to Juergen Bruder for providing me with a copy of the common DCT algorithm article, only to find out that I had
come to the same result in a more direct and comprehensible way with a more generative approach.