The Independent JPEG Group's JPEG software==========================================README for release 6b of 27-Mar-1998====================================This distribution contains the sixth public release of the Independent JPEGGroup's free JPEG software.  You are welcome to redistribute this software andto use it for any purpose, subject to the conditions under LEGAL ISSUES, below.Serious users of this software (particularly those incorporating it intolarger programs) should contact IJG at jpeg-info@uunet.uu.net to be added toour electronic mailing list.  Mailing list members are notified of updatesand 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 JPEGGroup.IJG is not affiliated with the official ISO JPEG standards committee.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.RELATED SOFTWARE    Other stuff you should get.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,                    rdjpgcom, and wrjpgcom.  *.1               Unix-style man pages for programs (same info as usage.doc).  wizard.doc        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.  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.Please read at least the files install.doc and usage.doc.  Useful informationcan also be found in the JPEG FAQ (Frequently Asked Questions) article.  SeeARCHIVE 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 ormore of the REFERENCES, then looking at the documentation files (in roughlythe order listed) before diving into the code.OVERVIEW========This package contains C software to implement JPEG image compression anddecompression.  JPEG (pronounced "jay-peg") is a standardized compressionmethod for full-color and gray-scale images.  JPEG is intended for compressing"real-world" scenes; line drawings, cartoons and other non-realistic imagesare not its strong suit.  JPEG is lossy, meaning that the output image is notexactly identical to the input image.  Hence you must not use JPEG if youhave to have identical output bits.  However, on typical photographic images,very good compression levels can be obtained with no visible change, andremarkably high compression levels are possible if you can tolerate alow-quality image.  For more details, see the references, or just experimentwith various compression settings.This software implements JPEG baseline, extended-sequential, and progressivecompression processes.  Provision is made for supporting all variants of theseprocesses, although some uncommon parameter settings aren't implemented yet.For legal reasons, we are not distributing code for the arithmetic-codingvariants of JPEG; see LEGAL ISSUES.  We have made no provision for supportingthe 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 toperform 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 includedconsiderable functionality beyond the bare JPEG coding/decoding capability;for example, the color quantization modules are not strictly part of JPEGdecoding, but they are essential for output to colormapped file formats orcolormapped displays.  These extra functions can be compiled out of thelibrary if not required for a particular application.  We have also included"jpegtran", a utility for lossless transcoding between different JPEGprocesses, and "rdjpgcom" and "wrjpgcom", two simple applications forinserting and extracting textual comments in JFIF files.The emphasis in designing this software has been on achieving portability andflexibility, 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 theREFERENCES section for introductory material.)  Rather, it is intended tobe reliable, portable, industrial-strength code.  We do not claim to haveachieved 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 productdocumentation, 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, orfitness 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.All Rights Reserved except as specified below.Permission is hereby granted to use, copy, modify, and distribute thissoftware (or portions thereof) for any purpose, without fee, subject to theseconditions:(1) If any part of the source code for this software is distributed, then thisREADME file must be included, with this copyright and no-warranty noticeunaltered; and any additions, deletions, or changes to the original filesmust be clearly indicated in accompanying documentation.(2) If only executable code is distributed, then the accompanyingdocumentation must state that "this software is based in part on the work ofthe Independent JPEG Group".(3) Permission for use of this software is granted only if the user acceptsfull responsibility for any undesirable consequences; the authors acceptNO 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 toacknowledge us.Permission is NOT granted for the use of any IJG author's name or company namein advertising or publicity relating to this software or products derived fromit.  This software may be referred to only as "the Independent JPEG Group'ssoftware".We specifically permit and encourage the use of this software as the basis ofcommercial products, provided that all warranty or liability claims areassumed 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 insteadby the usual distribution terms of the Free Software Foundation; principally,that you must include source code if you redistribute it.  (See the fileansi2knr.c for full details.)  However, since ansi2knr.c is not needed as partof any program generated from the IJG code, this does not limit you more thanthe 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,ltconfig, ltmain.sh).  Another support script, install-sh, is copyrightby M.I.T. but is also freely distributable.It appears that the arithmetic coding option of the JPEG spec is covered bypatents owned by IBM, AT&T, and Mitsubishi.  Hence arithmetic coding cannotlegally 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 unpatentedHuffman mode, it is unlikely that very many implementations will support it.)So far as we are aware, there are no patent restrictions on the remainingcode.The IJG distribution formerly included code to read and write GIF files.To avoid entanglement with the Unisys LZW patent, GIF reading support hasbeen removed altogether, and the GIF writer has been simplified to produce"uncompressed GIFs".  This technique does not use the LZW algorithm; theresulting GIF files are larger than usual, but are readable by all standardGIF decoders.We are required to state that    "The Graphics Interchange Format(c) is the Copyright property of