The Independent JPEG Group's JPEG software v6b
diff --git a/README b/README
index fa69a18..86cc206 100644
--- a/README
+++ b/README
@@ -1,8 +1,8 @@
The Independent JPEG Group's JPEG software
==========================================
-README for release 6a of 7-Feb-96
-=================================
+README for release 6b of 27-Mar-1998
+====================================
This distribution contains the sixth public release of the Independent JPEG
Group's free JPEG software. You are welcome to redistribute this software and
@@ -13,9 +13,10 @@
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, Luis Ortiz, Jim
-Boucher, Lee Crocker, Julian Minguillon, George Phillips, Davide Rossi,
-Ge' Weijers, and other members of the Independent JPEG Group.
+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.
IJG is not affiliated with the official ISO JPEG standards committee.
@@ -126,7 +127,7 @@
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) 1991-1996, Thomas G. Lane.
+This software is copyright (C) 1991-1998, Thomas G. Lane.
All Rights Reserved except as specified below.
Permission is hereby granted to use, copy, modify, and distribute this
@@ -166,8 +167,11 @@
of any program generated from the IJG code, this does not limit you more than
the foregoing paragraphs do.
-The configuration script "configure" was produced with GNU Autoconf. It
-is copyright by the Free Software Foundation but is freely distributable.
+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
@@ -178,13 +182,12 @@
So far as we are aware, there are no patent restrictions on the remaining
code.
-WARNING: Unisys has begun to enforce their patent on LZW compression against
-GIF encoders and decoders. You will need a license from Unisys to use the
-included rdgif.c or wrgif.c files in a commercial or shareware application.
-At this time, Unisys is not enforcing their patent against freeware, so
-distribution of this package remains legal. However, we intend to remove
-GIF support from the IJG package as soon as a suitable replacement format
-becomes reasonably popular.
+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
@@ -203,21 +206,21 @@
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 ftp.uu.net, graphics/jpeg/wallace.ps.gz. The file (actually
+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
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.
+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, published by M&T Books (Redwood
-City, CA), 1991, ISBN 1-55851-216-0. 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...
+"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...
The best full description of JPEG is the textbook "JPEG Still Image Data
Compression Standard" by William B. Pennebaker and Joan L. Mitchell, published
@@ -242,10 +245,9 @@
Continuous-tone Still Images, Part 2: Compliance testing" and has document
numbers ISO/IEC IS 10918-2, ITU-T T.83.
-Extensions to the original JPEG standard are defined in JPEG Part 3, a new ISO
-document. Part 3 is undergoing ISO balloting and is expected to be approved
-by the end of 1995; it will have document numbers ISO/IEC IS 10918-3, ITU-T
-T.84. IJG currently does not support any Part 3 extensions.
+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
@@ -255,24 +257,22 @@
1778 McCarthy Blvd.
Milpitas, CA 95035
phone (408) 944-6300, fax (408) 944-6314
-A PostScript version of this document is available at ftp.uu.net, file
-graphics/jpeg/jfif.ps.gz. It can also be obtained by e-mail from the C-Cube
-mail server, netlib@c3.pla.ca.us. Send the message "send jfif_ps from jpeg"
-to the server to obtain the JFIF document; send the message "help" if you have
-trouble.
+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.
-The TIFF 6.0 file format specification can be obtained by FTP from sgi.com
-(192.48.153.1), file graphics/tiff/TIFF6.ps.Z; or you can order a printed
-copy from Aldus Corp. at (206) 628-6593. The JPEG incorporation scheme
+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 sgi.com or
-from ftp.uu.net:/graphics/jpeg/. It is expected that the next revision of
-the TIFF spec will replace the 6.0 JPEG design with the Note's design.
+(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
+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 sgi.com:/graphics/tiff/.
+from ftp://ftp.sgi.com/graphics/tiff/.
ARCHIVE LOCATIONS
@@ -281,26 +281,27 @@
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 graphics/jpeg/jpegsrc.v6a.tar.gz. If you are on the Internet, you
-can retrieve files from ftp.uu.net by standard anonymous FTP. If you don't
-have FTP access, UUNET's archives are also available via UUCP; contact
+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.
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.coast.net:/SimTel/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 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.
-You can always obtain the latest version from the news.answers archive at
-rtfm.mit.edu. By FTP, fetch /pub/usenet/news.answers/jpeg-faq/part1 and
-.../part2. If you don't have FTP, send e-mail to mail-server@rtfm.mit.edu
+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
@@ -315,21 +316,20 @@
obtain them on Internet.
If you are on a Unix machine, we highly recommend Jef Poskanzer's free
-PBMPLUS image 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. You can obtain this package by FTP from ftp.x.org
-(contrib/pbmplus*.tar.Z) or ftp.ee.lbl.gov (pbmplus*.tar.Z). There is also
-a newer update of this package called NETPBM, available from
-wuarchive.wustl.edu under directory /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.
+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.
A different free JPEG implementation, written by the PVRG group at Stanford,
-is available from havefun.stanford.edu in directory pub/jpeg. This program
+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.
+which we do not. (On the other hand, it doesn't do progressive JPEG.)
FILE FORMAT WARS
@@ -370,14 +370,16 @@
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.
+
In future versions, we are considering supporting some of the upcoming JPEG
Part 3 extensions --- principally, variable quantization and the SPIFF file
format.
-Tuning the software for better behavior at low quality/high compression
-settings is also of interest. The current method for scaling the
-quantization tables is known not to be very good at low Q values.
-
-As always, speeding things up is high on our priority list.
+As always, speeding things up is of great interest.
Please send bug reports, offers of help, etc. to jpeg-info@uunet.uu.net.