Valve Developer Community:Third Party Legal Notices

The Source engine and Valve games use Third Party code for certain functions. The required legal notices for using such code are reproduced below in accordance with Valve’s obligations to provide such notices:

For mxtk

//                 mxToolKit (c) 1999 by Mete Ciragan
//
// last modified:  Mar 14 1999, Mete Ciragan
// copyright:      The programs and associated files contained in this
//                 distribution were developed by Mete Ciragan. The programs
//                 are not in the public domain, but they are freely
//                 distributable without licensing fees. These programs are
//                 provided without guarantee or warrantee expressed or
//                 implied.

For zlib

/* zlib.h -- interface of the 'zlib' general purpose compression library
  version 1.1.3, July 9th, 1998

  Copyright (C) 1995-1998 Jean-loup Gailly and Mark Adler

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.

  Jean-loup Gailly        Mark Adler
  jloup@gzip.org          madler@alumni.caltech.edu


  The data format used by the zlib library is described by RFCs (Request for
  Comments) 1950 to 1952 in the files ftp://ds.internic.net/rfc/rfc1950.txt
  (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
*/

For Xzip/Xunzip

// This is version 2002-Feb-16 of the Info-ZIP copyright and license. The 
// definitive version of this document should be available at 
// ftp://ftp.info-zip.org/pub/infozip/license.html indefinitely. 
// 
// Copyright (c) 1990-2002 Info-ZIP. All rights reserved. 
// 
// For the purposes of this copyright and license, "Info-ZIP" is defined as 
// the following set of individuals: 
// 
// Mark Adler, John Bush, Karl Davis, Harald Denker, Jean-Michel Dubois, 
// Jean-loup Gailly, Hunter Goatley, Ian Gorman, Chris Herborth, Dirk Haase, 
// Greg Hartwig, Robert Heath, Jonathan Hudson, Paul Kienitz, 
// David Kirschbaum, Johnny Lee, Onno van der Linden, Igor Mandrichenko, 
// Steve P. Miller, Sergio Monesi, Keith Owens, George Petrov, Greg Roelofs, 
// Kai Uwe Rommel, Steve Salisbury, Dave Smith, Christian Spieler, 
// Antoine Verheijen, Paul von Behren, Rich Wales, Mike White 
// 
// This software is provided "as is", without warranty of any kind, express 
// or implied. In no event shall Info-ZIP or its contributors be held liable 
// for any direct, indirect, incidental, special or consequential damages 
// arising out of the use of or inability to use this software. 
// 
// Permission is granted to anyone to use this software for any purpose, 
// including commercial applications, and to alter it and redistribute it 
// freely, subject to the following restrictions: 
// 
// 1. Redistributions of source code must retain the above copyright notice, 
// definition, disclaimer, and this list of conditions. 
// 
// 2. Redistributions in binary form (compiled executables) must reproduce 
// the above copyright notice, definition, disclaimer, and this list of 
// conditions in documentation and/or other materials provided with the 
// distribution. The sole exception to this condition is redistribution 
// of a standard UnZipSFX binary as part of a self-extracting archive; 
// that is permitted without inclusion of this license, as long as the 
// normal UnZipSFX banner has not been removed from the binary or disabled. 
// 
// 3. Altered versions--including, but not limited to, ports to new 
// operating systems, existing ports with new graphical interfaces, and 
// dynamic, shared, or static library versions--must be plainly marked 
// as such and must not be misrepresented as being the original source. 
// Such altered versions also must not be misrepresented as being 
// Info-ZIP releases--including, but not limited to, labeling of the 
// altered versions with the names "Info-ZIP" (or any variation thereof, 
// including, but not limited to, different capitalizations), 
// "Pocket UnZip", "WiZ" or "MacZip" without the explicit permission of 
// Info-ZIP. Such altered versions are further prohibited from 
// misrepresentative use of the Zip-Bugs or Info-ZIP e-mail addresses or 
// of the Info-ZIP URL(s). 
// 
// 4. Info-ZIP retains the right to use the names "Info-ZIP", "Zip", "UnZip", 
// "UnZipSFX", "WiZ", "Pocket UnZip", "Pocket Zip", and "MacZip" for its 
// own source and binary releases. 
// 
///////////////////////////////////////////////////////////////////////////////

For JPEG image support

The Source engine and SDK also make use of library functions for working with .jpg files. Specifically, the Source engine jpeg library is based in part on the work of the Independent JPEG Group (IJG). The original source code and project files for the IJG's JPEG libraries may be found at: http://www.ijg.org/files/jpegsrc.v6b.tar.gz

The following is the README file from that archive and is produced in accordance with the legal notices required by the library:

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 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. 

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 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 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 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 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) 1991-1998, Thomas G. Lane. 
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. 


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 instead 
by the usual distribution terms of the Free Software Foundation; principally, 
that you must include source code if you redistribute it. (See the file 
ansi2knr.c for full details.) However, since ansi2knr.c is not needed as part 
of any program generated from the IJG code, this does not limit you more than 
the 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 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. 

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 highly 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 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. 

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 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 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, 
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: 
   Literature Department 
   C-Cube Microsystems, Inc. 
   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. 

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 
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/. 


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. 

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. 
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 


RELATED SOFTWARE 
================ 

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. 

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. 

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.) 


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, 
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! 


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. 

As always, speeding things up is of great interest. 

Please send bug reports, offers of help, etc. to jpeg-info@uunet.uu.net.