Cross Reference: /external/chromium_org/third_party/libjpeg_turbo/

libjpeg-turbo note:  This file has been modified by The libjpeg-turbo Project
to include only information relevant to libjpeg-turbo, to wordsmith certain
sections, and to remove impolitic language that existed in the libjpeg v8
README.  It is included only for reference.  Please see README-turbo.txt for
information specific to libjpeg-turbo.


The Independent JPEG Group's JPEG software
==========================================

This distribution contains a 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.

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 ISO/IEC JTC1/SC29/WG1 standards committee
(also known as JPEG, together with ITU-T SG16).


DOCUMENTATION ROADMAP
=====================

This file contains the following sections:

OVERVIEW            General description of JPEG and the IJG software.
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.
FILE FORMAT WARS    Software *not* to get.
TO DO               Plans for future IJG releases.

Other documentation files in the distribution are:

User documentation:
  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.txt).
  wizard.txt        Advanced usage instructions for JPEG wizards only.
  change.log        Version-to-version change highlights.
Programmer and internal documentation:
  libjpeg.txt       How to use the JPEG library in your own programs.
  example.c         Sample code for calling the JPEG library.
  structure.txt     Overview of the JPEG library's internal structure.
  coderules.txt     Coding style rules --- please read if you contribute code.

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.

If you want to understand how the JPEG code works, we suggest reading one or
more of the REFERENCES, then looking at the documentation files (in roughly
the order listed) before diving into the code.


OVERVIEW
========

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.  JPEG's strong suit is compressing
photographic images or other types of images that have smooth color and
brightness transitions between neighboring pixels.  Images with sharp lines or
other abrupt features may not compress well with JPEG, and a higher JPEG
quality may have to be used to avoid visible compression artifacts with such
images.

JPEG is lossy, meaning that the output pixels are not necessarily identical to
the input pixels.  However, on photographic content and other "smooth" images,
very good compression ratios can be obtained with no visible compression
artifacts, and extremely high compression ratios are possible if you are
willing to sacrifice image quality (by reducing the "quality" setting in the
compressor.)

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.
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
perform conversion between JPEG and some other popular image file formats.
The library is intended to be reused in other applications.

In order to support file conversion and viewing software, we have included
considerable functionality beyond the bare JPEG coding/decoding capability;
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.

The emphasis in designing this software has been on achieving portability and
flexibility, while also making it fast enough to be useful.  In particular,
the software is not intended to be read as a tutorial on JPEG.  (See the
REFERENCES section for introductory material.)  Rather, it is intended to
be reliable, portable, industrial-strength code.  We do not claim to have
achieved that goal in every aspect of the software, but we strive for it.

We welcome the use of this software as a component of commercial products.
No royalty is required, but we do ask for an acknowledgement in product
documentation, as described under LEGAL ISSUES.


LEGAL ISSUES
============

In plain English:

1. We don't promise that this software works.  (But if you find any bugs,
   please let us know!)
2. You can use this software for whatever you want.  You don't have to pay us.
3. You may not pretend that you wrote this software.  If you use it in a
   program, you must acknowledge somewhere in your documentation that
   you've used the IJG code.

In legalese:

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) 1991-2012, 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.


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...

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).

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.

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.v8d.tar.gz, and in Windows-compatible
"zip" archive format as http://www.ijg.org/files/jpegsr8d.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


FILE FORMAT WARS
================

The ISO/IEC JTC1/SC29/WG1 standards committee (also known as JPEG, together
with ITU-T SG16) currently promotes different formats containing the name
"JPEG" which are incompatible with original DCT-based JPEG.  IJG therefore does
not support these formats (see REFERENCES).  Indeed, one of the original
reasons for developing this free software was to help 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
=====

Please send bug reports, offers of help, etc. to jpeg-info@jpegclub.org.
Name	Date	Size
..	12-Mar-2015	4 KiB
bmp.c	12-Mar-2015	7.8 KiB
bmp.h	12-Mar-2015	1.8 KiB
cderror.h	12-Mar-2015	5.2 KiB
cdjpeg.c	12-Mar-2015	4.6 KiB
cdjpeg.h	12-Mar-2015	6.1 KiB
change.log	12-Mar-2015	11.6 KiB
ChangeLog.txt	12-Mar-2015	19.8 KiB
cjpeg.c	12-Mar-2015	20.5 KiB
config.h	12-Mar-2015	3.9 KiB
djpeg.c	12-Mar-2015	20.8 KiB
example.c	12-Mar-2015	16.7 KiB
google.patch	12-Mar-2015	143.8 KiB
jaricom.c	12-Mar-2015	4.9 KiB
jcapimin.c	12-Mar-2015	9.2 KiB
jcapistd.c	12-Mar-2015	5.7 KiB
jcarith.c	12-Mar-2015	27.5 KiB
jccoefct.c	12-Mar-2015	16 KiB
jccolext.c	12-Mar-2015	4.4 KiB
jccolor.c	12-Mar-2015	21.2 KiB
jcdctmgr.c	12-Mar-2015	18.8 KiB
jchuff.c	12-Mar-2015	31.4 KiB
jchuff.h	12-Mar-2015	1.5 KiB
jcinit.c	12-Mar-2015	2.4 KiB
jcmainct.c	12-Mar-2015	9.1 KiB
jcmarker.c	12-Mar-2015	16.8 KiB
jcmaster.c	12-Mar-2015	20.4 KiB
jcomapi.c	12-Mar-2015	3 KiB
jconfig.h	12-Mar-2015	1.6 KiB
jcparam.c	12-Mar-2015	21.9 KiB
jcphuff.c	12-Mar-2015	24.5 KiB
jcprepct.c	12-Mar-2015	11.8 KiB
jcsample.c	12-Mar-2015	18.7 KiB
jctrans.c	12-Mar-2015	14 KiB
jdapimin.c	12-Mar-2015	12.3 KiB
jdapistd.c	12-Mar-2015	9.2 KiB
jdarith.c	12-Mar-2015	23.1 KiB
jdatadst-tj.c	12-Mar-2015	6.1 KiB
jdatadst.c	12-Mar-2015	8.8 KiB
jdatasrc-tj.c	12-Mar-2015	6.4 KiB
jdatasrc.c	12-Mar-2015	9.4 KiB
jdcoefct.c	12-Mar-2015	25 KiB
jdcolext.c	12-Mar-2015	4.3 KiB
jdcolor.c	12-Mar-2015	20.8 KiB
jdct.h	12-Mar-2015	9.4 KiB
jddctmgr.c	12-Mar-2015	10.2 KiB
jdhuff.c	12-Mar-2015	24.4 KiB
jdhuff.h	12-Mar-2015	9 KiB
jdinput.c	12-Mar-2015	13.6 KiB
jdmainct.c	12-Mar-2015	20.3 KiB
jdmarker.c	12-Mar-2015	45.7 KiB
jdmaster.c	12-Mar-2015	26.7 KiB
jdmerge.c	12-Mar-2015	15.1 KiB
jdmrgext.c	12-Mar-2015	5.9 KiB
jdphuff.c	12-Mar-2015	20.1 KiB
jdpostct.c	12-Mar-2015	9.5 KiB
jdsample.c	12-Mar-2015	16.6 KiB
jdtrans.c	12-Mar-2015	5.2 KiB
jerror.c	12-Mar-2015	7.6 KiB
jerror.h	12-Mar-2015	14.4 KiB
jfdctflt.c	12-Mar-2015	5.4 KiB
jfdctfst.c	12-Mar-2015	7.4 KiB
jfdctint.c	12-Mar-2015	10.8 KiB
jidctflt.c	12-Mar-2015	8.3 KiB
jidctfst.c	12-Mar-2015	12.9 KiB
jidctint.c	12-Mar-2015	94.3 KiB
jidctred.c	12-Mar-2015	13.2 KiB
jinclude.h	12-Mar-2015	3.2 KiB
jmemmgr.c	12-Mar-2015	41.2 KiB
jmemnobs.c	12-Mar-2015	2.7 KiB
jmemsys.h	12-Mar-2015	8 KiB
jmorecfg.h	12-Mar-2015	13.7 KiB
jpegcomp.h	12-Mar-2015	1 KiB
jpegint.h	12-Mar-2015	15.7 KiB
jpeglib.h	12-Mar-2015	49.2 KiB
jpeglibmangler.h	12-Mar-2015	6 KiB
jpegtran.c	12-Mar-2015	17.6 KiB
jpegut.c	12-Mar-2015	10.4 KiB
jpgtest.cxx	12-Mar-2015	11.9 KiB
jquant1.c	12-Mar-2015	30.8 KiB
jquant2.c	12-Mar-2015	47.1 KiB
jsimd.h	12-Mar-2015	4 KiB
jsimd_none.c	12-Mar-2015	5.6 KiB
jsimddct.h	12-Mar-2015	4.5 KiB
jutils.c	12-Mar-2015	5.1 KiB
jversion.h	12-Mar-2015	847
LGPL.txt	12-Mar-2015	25.8 KiB
libjpeg.gyp	12-Mar-2015	9 KiB
libjpeg.target.darwin-arm.mk	12-Mar-2015	8.5 KiB
libjpeg.target.darwin-arm64.mk	12-Mar-2015	8 KiB
libjpeg.target.darwin-mips.mk	12-Mar-2015	8.1 KiB
libjpeg.target.darwin-mips64.mk	12-Mar-2015	8.1 KiB
libjpeg.target.darwin-x86.mk	12-Mar-2015	50 KiB
libjpeg.target.darwin-x86_64.mk	12-Mar-2015	28.1 KiB
libjpeg.target.linux-arm.mk	12-Mar-2015	8.5 KiB
libjpeg.target.linux-arm64.mk	12-Mar-2015	8 KiB
libjpeg.target.linux-mips.mk	12-Mar-2015	8.1 KiB
libjpeg.target.linux-mips64.mk	12-Mar-2015	8.1 KiB
libjpeg.target.linux-x86.mk	12-Mar-2015	50 KiB
libjpeg.target.linux-x86_64.mk	12-Mar-2015	28.1 KiB
LICENSE.txt	12-Mar-2015	1.6 KiB
linux/	12-Mar-2015	4 KiB
mac/	12-Mar-2015	4 KiB
rdbmp.c	12-Mar-2015	14.7 KiB
rdcolmap.c	12-Mar-2015	6.7 KiB
rdgif.c	12-Mar-2015	1.2 KiB
rdjpgcom.c	12-Mar-2015	14.1 KiB
rdppm.c	12-Mar-2015	13.7 KiB
rdrle.c	12-Mar-2015	11.4 KiB
rdswitch.c	12-Mar-2015	12.2 KiB
rdtarga.c	12-Mar-2015	14.6 KiB
README	12-Mar-2015	13.6 KiB
README-turbo.txt	12-Mar-2015	21.9 KiB
README.chromium	12-Mar-2015	1.5 KiB
rrtimer.h	12-Mar-2015	2.1 KiB
rrutil.h	12-Mar-2015	1.9 KiB
simd/	12-Mar-2015	4 KiB
tjbench.c	12-Mar-2015	29.3 KiB
tjunittest.c	12-Mar-2015	16.6 KiB
tjutil.c	12-Mar-2015	2.1 KiB
tjutil.h	12-Mar-2015	1.9 KiB
transupp.c	12-Mar-2015	56.8 KiB
transupp.h	12-Mar-2015	9.5 KiB
turbojpeg-jni.c	12-Mar-2015	25.7 KiB
turbojpeg.c	12-Mar-2015	37 KiB
turbojpeg.h	12-Mar-2015	36.7 KiB
turbojpegl.c	12-Mar-2015	10.1 KiB
win/	12-Mar-2015	4 KiB
wrbmp.c	12-Mar-2015	13.6 KiB
wrgif.c	12-Mar-2015	12.6 KiB
wrjpgcom.c	12-Mar-2015	16.2 KiB
wrppm.c	12-Mar-2015	8.2 KiB
wrrle.c	12-Mar-2015	9 KiB
wrtarga.c	12-Mar-2015	7.3 KiB