The Independent JPEG Group's JPEG software v7
diff --git a/README b/README
index 86cc206..b504d74 100644
--- a/README
+++ b/README
@@ -1,22 +1,17 @@
The Independent JPEG Group's JPEG software
==========================================
-README for release 6b of 27-Mar-1998
-====================================
+README for release 7 of 27-Jun-2009
+===================================
-This distribution contains the sixth public release of the Independent JPEG
+This distribution contains the seventh public release of the Independent JPEG
Group's free JPEG software. You are welcome to redistribute this software and
to use it for any purpose, subject to the conditions under LEGAL ISSUES, below.
-Serious users of this software (particularly those incorporating it into
-larger programs) should contact IJG at jpeg-info@uunet.uu.net to be added to
-our electronic mailing list. Mailing list members are notified of updates
-and have a chance to participate in technical discussions, etc.
-
-This software is the work of Tom Lane, Philip Gladstone, Jim Boucher,
-Lee Crocker, Julian Minguillon, Luis Ortiz, George Phillips, Davide Rossi,
-Guido Vollbeding, Ge' Weijers, and other members of the Independent JPEG
-Group.
+This software is the work of Tom Lane, Guido Vollbeding, Philip Gladstone,
+Bill Allombert, Jim Boucher, Lee Crocker, Bob Friesenhahn, Ben Jackson,
+Julian Minguillon, Luis Ortiz, George Phillips, Davide Rossi, Ge' Weijers,
+and other members of the Independent JPEG Group.
IJG is not affiliated with the official ISO JPEG standards committee.
@@ -30,27 +25,27 @@
LEGAL ISSUES Copyright, lack of warranty, terms of distribution.
REFERENCES Where to learn more about JPEG.
ARCHIVE LOCATIONS Where to find newer versions of this software.
-RELATED SOFTWARE Other stuff you should get.
+ACKNOWLEDGMENTS Special thanks.
FILE FORMAT WARS Software *not* to get.
TO DO Plans for future IJG releases.
Other documentation files in the distribution are:
User documentation:
- install.doc How to configure and install the IJG software.
- usage.doc Usage instructions for cjpeg, djpeg, jpegtran,
+ install.txt How to configure and install the IJG software.
+ usage.txt Usage instructions for cjpeg, djpeg, jpegtran,
rdjpgcom, and wrjpgcom.
- *.1 Unix-style man pages for programs (same info as usage.doc).
- wizard.doc Advanced usage instructions for JPEG wizards only.
+ *.1 Unix-style man pages for programs (same info as usage.txt).
+ wizard.txt Advanced usage instructions for JPEG wizards only.
change.log Version-to-version change highlights.
Programmer and internal documentation:
- libjpeg.doc How to use the JPEG library in your own programs.
+ libjpeg.txt How to use the JPEG library in your own programs.
example.c Sample code for calling the JPEG library.
- structure.doc Overview of the JPEG library's internal structure.
- filelist.doc Road map of IJG files.
- coderules.doc Coding style rules --- please read if you contribute code.
+ structure.txt Overview of the JPEG library's internal structure.
+ filelist.txt Road map of IJG files.
+ coderules.txt Coding style rules --- please read if you contribute code.
-Please read at least the files install.doc and usage.doc. Useful information
+Please read at least the files install.txt and usage.txt. Some information
can also be found in the JPEG FAQ (Frequently Asked Questions) article. See
ARCHIVE LOCATIONS below to find out where to obtain the FAQ article.
@@ -62,24 +57,15 @@
OVERVIEW
========
-This package contains C software to implement JPEG image compression and
-decompression. JPEG (pronounced "jay-peg") is a standardized compression
-method for full-color and gray-scale images. JPEG is intended for compressing
-"real-world" scenes; line drawings, cartoons and other non-realistic images
-are not its strong suit. JPEG is lossy, meaning that the output image is not
-exactly identical to the input image. Hence you must not use JPEG if you
-have to have identical output bits. However, on typical photographic images,
-very good compression levels can be obtained with no visible change, and
-remarkably high compression levels are possible if you can tolerate a
-low-quality image. For more details, see the references, or just experiment
-with various compression settings.
+This package contains C software to implement JPEG image encoding, decoding,
+and transcoding. JPEG (pronounced "jay-peg") is a standardized compression
+method for full-color and gray-scale images.
This software implements JPEG baseline, extended-sequential, and progressive
compression processes. Provision is made for supporting all variants of these
processes, although some uncommon parameter settings aren't implemented yet.
-For legal reasons, we are not distributing code for the arithmetic-coding
-variants of JPEG; see LEGAL ISSUES. We have made no provision for supporting
-the hierarchical or lossless processes defined in the standard.
+We have made no provision for supporting the hierarchical or lossless
+processes defined in the standard.
We provide a set of library routines for reading and writing JPEG image files,
plus two sample applications "cjpeg" and "djpeg", which use the library to
@@ -91,10 +77,11 @@
for example, the color quantization modules are not strictly part of JPEG
decoding, but they are essential for output to colormapped file formats or
colormapped displays. These extra functions can be compiled out of the
-library if not required for a particular application. We have also included
-"jpegtran", a utility for lossless transcoding between different JPEG
-processes, and "rdjpgcom" and "wrjpgcom", two simple applications for
-inserting and extracting textual comments in JFIF files.
+library if not required for a particular application.
+
+We have also included "jpegtran", a utility for lossless transcoding between
+different JPEG processes, and "rdjpgcom" and "wrjpgcom", two simple
+applications for inserting and extracting textual comments in JFIF files.
The emphasis in designing this software has been on achieving portability and
flexibility, while also making it fast enough to be useful. In particular,
@@ -127,7 +114,7 @@
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) 1991-1998, Thomas G. Lane.
+This software is copyright (C) 1991-2009, Thomas G. Lane, Guido Vollbeding.
All Rights Reserved except as specified below.
Permission is hereby granted to use, copy, modify, and distribute this
@@ -170,17 +157,8 @@
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,
-ltconfig, ltmain.sh). Another support script, install-sh, is copyright
-by M.I.T. but is also freely distributable.
-
-It appears that the arithmetic coding option of the JPEG spec is covered by
-patents owned by IBM, AT&T, and Mitsubishi. Hence arithmetic coding cannot
-legally be used without obtaining one or more licenses. For this reason,
-support for arithmetic coding has been removed from the free JPEG software.
-(Since arithmetic coding provides only a marginal gain over the unpatented
-Huffman mode, it is unlikely that very many implementations will support it.)
-So far as we are aware, there are no patent restrictions on the remaining
-code.
+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
@@ -198,7 +176,7 @@
REFERENCES
==========
-We highly recommend reading one or more of these references before trying to
+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
@@ -207,7 +185,7 @@
(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 ftp://ftp.uu.net/graphics/jpeg/wallace.ps.gz. The file (actually
+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,
@@ -222,33 +200,28 @@
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 full 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). This is by far the most complete exposition of JPEG
-in existence, and we highly recommend it.
+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 JPEG standard itself is not available electronically; you must order a
-paper copy through ISO or ITU. (Unless you feel a need to own a certified
-official copy, we recommend buying the Pennebaker and Mitchell book instead;
-it's much cheaper and includes a great deal of useful explanatory material.)
-In the USA, copies of the standard may be ordered from ANSI Sales at (212)
-642-4900, or from Global Engineering Documents at (800) 854-7179. (ANSI
-doesn't take credit card orders, but Global does.) It's not cheap: as of
-1992, ANSI was charging $95 for Part 1 and $47 for Part 2, plus 7%
-shipping/handling. The 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,
+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.
-Some extensions to the original JPEG standard are defined in JPEG Part 3,
-a newer ISO standard numbered ISO/IEC IS 10918-3 and ITU-T T.84. IJG
-currently does not support any Part 3 extensions.
-
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. A copy of the JFIF spec is available from:
@@ -257,47 +230,33 @@
1778 McCarthy Blvd.
Milpitas, CA 95035
phone (408) 944-6300, fax (408) 944-6314
-A PostScript version of this document is available by FTP at
-ftp://ftp.uu.net/graphics/jpeg/jfif.ps.gz. There is also a plain text
-version at ftp://ftp.uu.net/graphics/jpeg/jfif.txt.gz, but it is missing
-the figures.
+A PostScript version of this 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 ftp.sgi.com or
-from ftp://ftp.uu.net/graphics/jpeg/. It is expected that the next revision
+(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. libtiff is available
-from ftp://ftp.sgi.com/graphics/tiff/.
+uses our library to implement TIFF/JPEG per the Note.
ARCHIVE LOCATIONS
=================
-The "official" archive site for this software is ftp.uu.net (Internet
-address 192.48.96.9). The most recent released version can always be found
-there in directory graphics/jpeg. This particular version will be archived
-as ftp://ftp.uu.net/graphics/jpeg/jpegsrc.v6b.tar.gz. If you don't have
-direct Internet access, UUNET's archives are also available via UUCP; contact
-help@uunet.uu.net for information on retrieving files that way.
+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.v7.tar.gz, and in Windows-compatible
+"zip" archive format as http://www.ijg.org/files/jpegsr7.zip.
-Numerous Internet sites maintain copies of the UUNET files. However, only
-ftp.uu.net is guaranteed to have the latest official version.
-
-You can also obtain this software in DOS-compatible "zip" archive format from
-the SimTel archives (ftp://ftp.simtel.net/pub/simtelnet/msdos/graphics/), or
-on CompuServe in the Graphics Support forum (GO CIS:GRAPHSUP), library 12
-"JPEG Tools". Again, these versions may sometimes lag behind the ftp.uu.net
-release.
-
-The JPEG FAQ (Frequently Asked Questions) article is a useful source of
-general information about JPEG. It is updated constantly and therefore is
-not included in this distribution. The FAQ is posted every two weeks to
-Usenet newsgroups comp.graphics.misc, news.answers, and other groups.
+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/.
@@ -307,79 +266,57 @@
send usenet/news.answers/jpeg-faq/part2
-RELATED SOFTWARE
-================
+ACKNOWLEDGMENTS
+===============
-Numerous viewing and image manipulation programs now support JPEG. (Quite a
-few of them use this library to do so.) The JPEG FAQ described above lists
-some of the more popular free and shareware viewers, and tells where to
-obtain them on Internet.
+Thank to Juergen Bruder of the Georg-Cantor-Organization at the
+Martin-Luther-University Halle 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.
-If you are on a Unix machine, we highly recommend Jef Poskanzer's free
-PBMPLUS software, which provides many useful operations on PPM-format image
-files. In particular, it can convert PPM images to and from a wide range of
-other formats, thus making cjpeg/djpeg considerably more useful. The latest
-version is distributed by the NetPBM group, and is available from numerous
-sites, notably ftp://wuarchive.wustl.edu/graphics/graphics/packages/NetPBM/.
-Unfortunately PBMPLUS/NETPBM is not nearly as portable as the IJG software is;
-you are likely to have difficulty making it work on any non-Unix machine.
+Thank to Istvan Sebestyen and Joan L. Mitchell for inviting me to the
+ITU JPEG (Study Group 16) meeting in Geneva, Switzerland.
-A different free JPEG implementation, written by the PVRG group at Stanford,
-is available from ftp://havefun.stanford.edu/pub/jpeg/. This program
-is designed for research and experimentation rather than production use;
-it is slower, harder to use, and less portable than the IJG code, but it
-is easier to read and modify. Also, the PVRG code supports lossless JPEG,
-which we do not. (On the other hand, it doesn't do progressive JPEG.)
+Thank to Thomas Wiegand and Gary Sullivan for inviting me to the
+Joint Video Team (MPEG & ITU) meeting in Geneva, Switzerland.
+
+Thank to John Korejwa and Massimo Ballerini for inviting me to
+fruitful consultations in Boston, MA and Milan, Italy.
+
+Thank to Hendrik Elstner, Roland Fassauer, and Simone Zuck for
+corresponding business development.
+
+Thank to Nico Zschach and Dirk Stelling of the technical support team
+at the Digital Images company in Halle for providing me with extra
+equipment for configuration tests.
+
+Thank to Richard F. Lyon (then of Foveon Inc.) for fruitful
+communication about JPEG configuration in Sigma Photo Pro software.
+
+Last but not least special thank to Thomas G. Lane for the original
+design and development of this singular software package.
FILE FORMAT WARS
================
-Some JPEG programs produce files that are not compatible with our library.
-The root of the problem is that the ISO JPEG committee failed to specify a
-concrete file format. Some vendors "filled in the blanks" on their own,
-creating proprietary formats that no one else could read. (For example, none
-of the early commercial JPEG implementations for the Macintosh were able to
-exchange compressed files.)
-
-The file format we have adopted is called JFIF (see REFERENCES). This format
-has been agreed to by a number of major commercial JPEG vendors, and it has
-become the de facto standard. JFIF is a minimal or "low end" representation.
-We recommend the use of TIFF/JPEG (TIFF revision 6.0 as modified by TIFF
-Technical Note #2) for "high end" applications that need to record a lot of
-additional data about an image. TIFF/JPEG is fairly new and not yet widely
-supported, unfortunately.
-
-The upcoming JPEG Part 3 standard defines a file format called SPIFF.
-SPIFF is interoperable with JFIF, in the sense that most JFIF decoders should
-be able to read the most common variant of SPIFF. SPIFF has some technical
-advantages over JFIF, but its major claim to fame is simply that it is an
-official standard rather than an informal one. At this point it is unclear
-whether SPIFF will supersede JFIF or whether JFIF will remain the de-facto
-standard. IJG intends to support SPIFF once the standard is frozen, but we
-have not decided whether it should become our default output format or not.
-(In any case, our decoder will remain capable of reading JFIF indefinitely.)
-
-Various proprietary file formats incorporating JPEG compression also exist.
-We have little or no sympathy for the existence of these formats. Indeed,
+The ISO JPEG standards committee actually promotes different formats like
+JPEG-2000 or JPEG-XR which are incompatible with original DCT-based JPEG
+and which are based on faulty technologies. IJG therefore does not and
+will not support such momentary mistakes (see REFERENCES).
+We have little or no sympathy for the promotion of these formats. Indeed,
one of the original reasons for developing this free software was to help
-force convergence on common, open format standards for JPEG files. Don't
-use a proprietary file format!
+force convergence on common, interoperable format standards for JPEG files.
+Don't use an incompatible file format!
+(In any case, our decoder will remain capable of reading existing JPEG
+image files indefinitely.)
TO DO
=====
-The major thrust for v7 will probably be improvement of visual quality.
-The current method for scaling the quantization tables is known not to be
-very good at low Q values. We also intend to investigate block boundary
-smoothing, "poor man's variable quantization", and other means of improving
-quality-vs-file-size performance without sacrificing compatibility.
+v7 is basically just a necessary interim release, paving the way for a
+major breakthrough in image coding technology with the next v8 package
+which is scheduled for release in the year 2010.
-In future versions, we are considering supporting some of the upcoming JPEG
-Part 3 extensions --- principally, variable quantization and the SPIFF file
-format.
-
-As always, speeding things up is of great interest.
-
-Please send bug reports, offers of help, etc. to jpeg-info@uunet.uu.net.
+Please send bug reports, offers of help, etc. to jpeg-info@jpegclub.org.