-README for libpng 1.0.3 - January 14, 1999 (shared library 2.1)
+README for libpng version 1.5.7 - December 15, 2011 (shared library 15.0)
See the note about version numbers near the top of png.h
See INSTALL for instructions on how to install libpng.
-This is the first official release of libpng. Don't let the fact that
-it's the first release fool you. The libpng library has been in
-extensive use and testing for about two and a half years. However, it's
-finally gotten to the stage where there haven't been significant
+Libpng comes in several distribution formats. Get libpng-*.tar.gz,
+libpng-*.tar.xz or libpng-*.tar.bz2 if you want UNIX-style line endings
+in the text files, or lpng*.zip if you want DOS-style line endings.
+
+Version 0.89 was the first official release of libpng. Don't let the
+fact that it's the first release fool you. The libpng library has been in
+extensive use and testing since mid-1995. By late 1997 it had
+finally gotten to the stage where there hadn't been significant
changes to the API in some time, and people have a bad feeling about
-libraries with versions < 1.0.
+libraries with versions < 1.0. Version 1.0.0 was released in
+March 1998.
****
Note that some of the changes to the png_info structure render this
It is important to note that the APIs do not make current programs
that access the info struct directly incompatible with the new
library. However, it is strongly suggested that new programs use
-the new APIs (as shown in example.c), and older programs be converted
-to the new format, to facilitate upgrades in the future.
+the new APIs (as shown in example.c and pngtest.c), and older programs
+be converted to the new format, to facilitate upgrades in the future.
****
Additions since 0.90 include the ability to compile libpng as a
critical or an ancillary chunk.
The changes made to the library, and bugs fixed are based on discussions
-on the PNG implementation mailing list <png-implement@dworking.wustl.edu>
-and not on material submitted to Guy.
+on the PNG-implement mailing list and not on material submitted
+privately to Guy, Andreas, or Glenn. They will forward any good
+suggestions to the list.
-For a detailed description on using libpng, read libpng.txt. For
+For a detailed description on using libpng, read libpng-manual.txt. For
examples of libpng in a program, see example.c and pngtest.c. For usage
information and restrictions (what little they are) on libpng, see
png.h. For a description on using zlib (the compression library used by
You can use zlib as a drop-in replacement for fread() and fwrite() if
you are so inclined.
-zlib should be available at the same place that libpng is.
-If not, it should be at ftp.uu.net in /graphics/png
-Eventually, it will be at ftp.uu.net in /pub/archiving/zip/zlib
+zlib should be available at the same place that libpng is, or at.
+ftp://ftp.info-zip.org/pub/infozip/zlib
You may also want a copy of the PNG specification. It is available
-as an RFC and a W3C Recommendation. Failing
-these resources you can try ftp.uu.net in the /graphics/png directory.
+as an RFC, a W3C Recommendation, and an ISO/IEC Standard. You can find
+these at http://www.libpng.org/pub/png/documents/
-This code is currently being archived at ftp.uu.net in the
-/graphics/png directory, and on CompuServe, Lib 20 (PNG SUPPORT)
+This code is currently being archived at libpng.sf.net in the
+[DOWNLOAD] area, and on CompuServe, Lib 20 (PNG SUPPORT)
at GO GRAPHSUP. If you can't find it in any of those places,
e-mail me, and I'll help you find it.
fix. Please mention "libpng" somewhere in the subject line. Thanks.
This release was created and will be supported by myself (of course
-based in a large way on Guy's and Andreas' earlier work), and the PNG group.
+based in a large way on Guy's and Andreas' earlier work), and the PNG
+development group.
-randeg@alumni.rpi.edu
-png-implement@dworkin.wustl.edu
+Send comments/corrections/commendations to png-mng-implement at
+lists.sourceforge.net (subscription required; visit
+https://lists.sourceforge.net/lists/listinfo/png-mng-implement
+to subscribe) or to glennrp at users.sourceforge.net
You can't reach Guy, the original libpng author, at the addresses
-given in previous versions of this document. He and Andreas will read mail
-addressed to the png-implement list, however.
+given in previous versions of this document. He and Andreas will
+read mail addressed to the png-implement list, however.
Please do not send general questions about PNG. Send them to
-the address in the specification (png-group@w3.org). At the same
-time, please do not send libpng questions to that address, send them to me
-or to png-implement@dworkin.wustl.edu. I'll
-get them in the end anyway. If you have a question about something
+png-mng-misc at lists.sf.net (subscription required; visit
+https://lists.sourceforge.net/lists/listinfo/png-mng-misc to
+subscribe). If you have a question about something
in the PNG specification that is related to using libpng, send it
to me. Send me any questions that start with "I was using libpng,
and ...". If in doubt, send questions to me. I'll bounce them
to others, if necessary.
Please do not send suggestions on how to change PNG. We have
-been discussing PNG for three years now, and it is official and
+been discussing PNG for sixteen years now, and it is official and
finished. If you have suggestions for libpng, however, I'll
-gladly listen. Even if your suggestion is not used for version
-1.0, it may be used later.
+gladly listen. Even if your suggestion is not used immediately,
+it may be used later.
Files in this distribution:
+ ANNOUNCE => Announcement of this version, with recent changes
CHANGES => Description of changes between libpng versions
+ KNOWNBUG => List of known bugs and deficiencies
+ LICENSE => License to use and redistribute libpng
README => This file
TODO => Things not implemented in the current library
- ansi2knr.1 => Manual page for ansi2knr
- ansi2knr.c => Converts files to K&R style function declarations
- build.bat => MS-DOS batch file for Borland compiler
- descrip.mms => VMS project file
+ Y2KINFO => Statement of Y2K compliance
example.c => Example code for using libpng functions
- libpng.3 => manual page for libpng
- libpng.txt => Description of libpng and its functions
+ libpng.3 => manual page for libpng (includes libpng-manual.txt)
+ libpng-manual.txt => Description of libpng and its functions
libpngpf.3 => manual page for libpng's private functions
png.5 => manual page for the PNG format
png.c => Basic interface functions common to library
- png.h => Library function and interface declarations
- pngconf.h => System specific library configuration
+ png.h => Library function and interface declarations (public)
+ pngpriv.h => Library function and interface declarations (private)
+ pngconf.h => System specific library configuration (public)
+ pngstruct.h => png_struct declaration (private)
+ pnginfo.h => png_info struct declaration (private)
+ pngdebug.h => debugging macros (private)
pngerror.c => Error/warning message I/O functions
pngget.c => Functions for retrieving info from struct
pngmem.c => Memory handling functions
+ pngbar.png => PNG logo, 88x31
+ pngnow.png => PNG logo, 98x31
pngpread.c => Progressive reading functions
pngread.c => Read data/helper high-level functions
pngrio.c => Lowest-level data read I/O functions
pngwrite.c => High-level write functions
pngwtran.c => Write data transformations
pngwutil.c => Write utility functions
+ contrib => Contributions
+ gregbook => source code for PNG reading and writing, from
+ Greg Roelofs' "PNG: The Definitive Guide",
+ O'Reilly, 1999
+ msvctest => Builds and runs pngtest using a MSVC workspace
+ pngminus => Simple pnm2png and png2pnm programs
+ pngsuite => Test images
+ visupng => Contains a MSVC workspace for VisualPng
+ projects => Contains project files and workspaces for
+ building a DLL
+ cbuilder5 => Contains a Borland workspace for building
+ libpng and zlib
+ visualc6 => Contains a Microsoft Visual C++ (MSVC)
+ workspace for building libpng and zlib
+ visualc71 => Contains a Microsoft Visual C++ (MSVC)
+ workspace for building libpng and zlib
+ xcode => Contains an Apple xcode
+ workspace for building libpng and zlib
scripts => Directory containing scripts for building libpng:
- descrip.mms => VMS makefile for MMS or MMK
- makefile.std => Generic UNIX makefile
- makefile.knr => Archaic UNIX Makefile that converts files with ansi2knr
- makefile.dec => DEC Alpha UNIX makefile
- makefile.hux => HPUX (10.20 and 11.00) makefile
- makefile.sgi => Silicon Graphics IRIX makefile
- makefile.sun => Sun makefile
- makefile.s2x => Solaris 2.X makefile (gcc, creates libpng.so.2.1.0)
- makefile.lnx => Linux/ELF makefile (gcc, creates libpng.so.2.1.0)
- makefile.mip => MIPS makefile
- makefile.aco => Acorn makefile
- makefile.ama => Amiga makefile
- smakefile.ppc => AMIGA smakefile for SAS C V6.58/7.00 PPC compiler
- (Requires SCOPTIONS, copied from scripts/SCOPTIONS.ppc)
- makefile.atr => Atari makefile
- makefile.bor => Borland makefile
- build.bat => MS-DOS batch file for Borland compiler
- makefile.dj2 => DJGPP 2 makefile
- makefile.msc => Microsoft C makefile
- makefile.w32 => makefile for Microsoft Visual C++ 4.0 and later
- makefile.tc3 => Turbo C 3.0 makefile
- makefile.os2 => OS/2 Makefile (gcc and emx, requires pngos2.def)
- makefile.wat => Watcom 10a+ Makefile, 32-bit flat memory model
- pngos2.def => OS/2 module definition file used by makefile.os2
- makevms.com => VMS build script
- pngdll.mak => To make a png32bd.dll with Borland C++ 4.5
- pngdef.pas => Defines for a png32bd.dll with Borland C++ 4.5
+ (see scripts/README.txt for the list of scripts)
Good luck, and happy coding.
--Glenn Randers-Pehrson
- Internet: randeg@alumni.rpi.edu
- Web: http://www.rpi.edu/~randeg/index.html
+-Glenn Randers-Pehrson (current maintainer, since 1998)
+ Internet: glennrp at users.sourceforge.net
--Andreas Eric Dilger
- Internet: adilger@enel.ucalgary.ca
+-Andreas Eric Dilger (former maintainer, 1996-1997)
+ Internet: adilger at enel.ucalgary.ca
Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/
--Guy Eric Schalnat
+-Guy Eric Schalnat (original author and former maintainer, 1995-1996)
(formerly of Group 42, Inc)
- Internet: gschal@infinet.com
+ Internet: gschal at infinet.com