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diff --git a/media/libjpeg/README.ijg b/media/libjpeg/README.ijg index 9c450ceb07..9453c19501 100644 --- a/media/libjpeg/README.ijg +++ b/media/libjpeg/README.ijg @@ -43,7 +43,7 @@ User documentation: 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. + example.txt 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. @@ -128,7 +128,7 @@ 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) 1991-2016, Thomas G. Lane, Guido Vollbeding. +This software is copyright (C) 1991-2020, Thomas G. Lane, Guido Vollbeding. All Rights Reserved except as specified below. Permission is hereby granted to use, copy, modify, and distribute this @@ -159,25 +159,6 @@ 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 (now expired), 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 ========== @@ -185,8 +166,8 @@ 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. + 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 PDF file containing a revised version of Wallace's article is @@ -220,21 +201,21 @@ 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 +format. For the omitted details, we follow the "JFIF" conventions, revision +1.02. JFIF version 1 has been adopted as ISO/IEC 10918-5 (05/2013) and +Recommendation ITU-T T.871 (05/2011): Information technology - Digital +compression and coding of continuous-tone still images: JPEG File Interchange +Format (JFIF). It is available as a free download in PDF file format from +https://www.iso.org/standard/54989.html and http://www.itu.int/rec/T-REC-T.871. +A PDF file of the older JFIF 1.02 specification is available at +http://www.w3.org/Graphics/JPEG/jfif3.pdf. + +The TIFF 6.0 file format specification can be obtained from +http://mirrors.ctan.org/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 @@ -249,28 +230,26 @@ The most recent released version can always be found there in directory "files". 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.) +general information about JPEG. It is available at +http://www.faqs.org/faqs/jpeg-faq. + + +FILE FORMAT COMPATIBILITY +========================= + +This software implements ITU T.81 | ISO/IEC 10918 with some extensions from +ITU T.871 | ISO/IEC 10918-5 (JPEG File Interchange Format-- see REFERENCES). +Informally, the term "JPEG image" or "JPEG file" most often refers to JFIF or +a subset thereof, but there are other formats containing the name "JPEG" that +are incompatible with the DCT-based JPEG standard or with JFIF (for instance, +JPEG 2000 and JPEG XR). This software therefore does not support these +formats. Indeed, one of the original reasons for developing this free software +was to help force convergence on a common, interoperable format standard for +JPEG files. + +JFIF is a minimal or "low end" representation. TIFF/JPEG (TIFF revision 6.0 as +modified by TIFF Technical Note #2) can be used for "high end" applications +that need to record a lot of additional data about an image. TO DO |