1 README for libpng version 1.2.29 - May 8, 2008 (shared library 12.0)
2 See the note about version numbers near the top of png.h
4 See INSTALL for instructions on how to install libpng.
6 Libpng comes in several distribution formats. Get libpng-*.tar.gz,
7 libpng-*.tar.lzma, or libpng-*.tar.bz2 if you want UNIX-style line
8 endings in the text files, or lpng*.7z or lpng*.zip if you want DOS-style
11 Version 0.89 was the first official release of libpng. Don't let the
12 fact that it's the first release fool you. The libpng library has been in
13 extensive use and testing since mid-1995. By late 1997 it had
14 finally gotten to the stage where there hadn't been significant
15 changes to the API in some time, and people have a bad feeling about
16 libraries with versions < 1.0. Version 1.0.0 was released in
20 Note that some of the changes to the png_info structure render this
21 version of the library binary incompatible with libpng-0.89 or
22 earlier versions if you are using a shared library. The type of the
23 "filler" parameter for png_set_filler() has changed from png_byte to
24 png_uint_32, which will affect shared-library applications that use
27 To avoid problems with changes to the internals of png_info_struct,
28 new APIs have been made available in 0.95 to avoid direct application
29 access to info_ptr. These functions are the png_set_<chunk> and
30 png_get_<chunk> functions. These functions should be used when
31 accessing/storing the info_struct data, rather than manipulating it
32 directly, to avoid such problems in the future.
34 It is important to note that the APIs do not make current programs
35 that access the info struct directly incompatible with the new
36 library. However, it is strongly suggested that new programs use
37 the new APIs (as shown in example.c and pngtest.c), and older programs
38 be converted to the new format, to facilitate upgrades in the future.
41 Additions since 0.90 include the ability to compile libpng as a
42 Windows DLL, and new APIs for accessing data in the info struct.
43 Experimental functions include the ability to set weighting and cost
44 factors for row filter selection, direct reads of integers from buffers
45 on big-endian processors that support misaligned data access, faster
46 methods of doing alpha composition, and more accurate 16->8 bit color
49 The additions since 0.89 include the ability to read from a PNG stream
50 which has had some (or all) of the signature bytes read by the calling
51 application. This also allows the reading of embedded PNG streams that
52 do not have the PNG file signature. As well, it is now possible to set
53 the library action on the detection of chunk CRC errors. It is possible
54 to set different actions based on whether the CRC error occurred in a
55 critical or an ancillary chunk.
57 The changes made to the library, and bugs fixed are based on discussions
58 on the PNG-implement mailing list
59 and not on material submitted privately to Guy, Andreas, or Glenn. They will
60 forward any good suggestions to the list.
62 For a detailed description on using libpng, read libpng.txt. For
63 examples of libpng in a program, see example.c and pngtest.c. For usage
64 information and restrictions (what little they are) on libpng, see
65 png.h. For a description on using zlib (the compression library used by
66 libpng) and zlib's restrictions, see zlib.h
68 I have included a general makefile, as well as several machine and
69 compiler specific ones, but you may have to modify one for your own needs.
71 You should use zlib 1.0.4 or later to run this, but it MAY work with
72 versions as old as zlib 0.95. Even so, there are bugs in older zlib
73 versions which can cause the output of invalid compression streams for
74 some images. You will definitely need zlib 1.0.4 or later if you are
75 taking advantage of the MS-DOS "far" structure allocation for the small
76 and medium memory models. You should also note that zlib is a
77 compression library that is useful for more things than just PNG files.
78 You can use zlib as a drop-in replacement for fread() and fwrite() if
81 zlib should be available at the same place that libpng is, or at
82 ftp://ftp.simplesystems.org/pub/png/src/
84 You may also want a copy of the PNG specification. It is available
85 as an RFC, a W3C Recommendation, and an ISO/IEC Standard. You can find
86 these at http://www.libpng.org/pub/png/pngdocs.html
88 This code is currently being archived at libpng.sf.net in the
89 [DOWNLOAD] area, and on CompuServe, Lib 20 (PNG SUPPORT)
90 at GO GRAPHSUP. If you can't find it in any of those places,
91 e-mail me, and I'll help you find it.
93 If you have any code changes, requests, problems, etc., please e-mail
94 them to me. Also, I'd appreciate any make files or project files,
95 and any modifications you needed to make to get libpng to compile,
96 along with a #define variable to tell what compiler/system you are on.
97 If you needed to add transformations to libpng, or wish libpng would
98 provide the image in a different way, drop me a note (and code, if
99 possible), so I can consider supporting the transformation.
100 Finally, if you get any warning messages when compiling libpng
101 (note: not zlib), and they are easy to fix, I'd appreciate the
102 fix. Please mention "libpng" somewhere in the subject line. Thanks.
104 This release was created and will be supported by myself (of course
105 based in a large way on Guy's and Andreas' earlier work), and the PNG group.
107 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
108 (subscription required; visit
109 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
110 to subscribe) or to glennrp at users.sourceforge.net
112 You can't reach Guy, the original libpng author, at the addresses
113 given in previous versions of this document. He and Andreas will read mail
114 addressed to the png-implement list, however.
116 Please do not send general questions about PNG. Send them to
117 the (png-mng-misc at lists.sourceforge.net, subscription required, visit
118 https://lists.sourceforge.net/lists/listinfo/png-mng-implement to subscribe)
120 please do not send libpng questions to that address, send them to me
121 or to the png-implement list. I'll
122 get them in the end anyway. If you have a question about something
123 in the PNG specification that is related to using libpng, send it
124 to me. Send me any questions that start with "I was using libpng,
125 and ...". If in doubt, send questions to me. I'll bounce them
126 to others, if necessary.
128 Please do not send suggestions on how to change PNG. We have
129 been discussing PNG for twelve years now, and it is official and
130 finished. If you have suggestions for libpng, however, I'll
131 gladly listen. Even if your suggestion is not used immediately,
132 it may be used later.
134 Files in this distribution:
136 ANNOUNCE => Announcement of this version, with recent changes
137 CHANGES => Description of changes between libpng versions
138 KNOWNBUG => List of known bugs and deficiencies
139 LICENSE => License to use and redistribute libpng
141 TODO => Things not implemented in the current library
142 Y2KINFO => Statement of Y2K compliance
143 example.c => Example code for using libpng functions
144 libpng-*-*-diff.txt => Diff from previous release
145 libpng.3 => manual page for libpng (includes libpng.txt)
146 libpng.txt => Description of libpng and its functions
147 libpngpf.3 => manual page for libpng's private functions
148 png.5 => manual page for the PNG format
149 png.c => Basic interface functions common to library
150 png.h => Library function and interface declarations
151 pngconf.h => System specific library configuration
152 pngerror.c => Error/warning message I/O functions
153 pngget.c => Functions for retrieving info from struct
154 pngmem.c => Memory handling functions
155 pngbar.png => PNG logo, 88x31
156 pngnow.png => PNG logo, 98x31
157 pngpread.c => Progressive reading functions
158 pngread.c => Read data/helper high-level functions
159 pngrio.c => Lowest-level data read I/O functions
160 pngrtran.c => Read data transformation functions
161 pngrutil.c => Read data utility functions
162 pngset.c => Functions for storing data into the info_struct
163 pngtest.c => Library test program
164 pngtest.png => Library test sample image
165 pngtrans.c => Common data transformation functions
166 pngwio.c => Lowest-level write I/O functions
167 pngwrite.c => High-level write functions
168 pngwtran.c => Write data transformations
169 pngwutil.c => Write utility functions
170 contrib => Contributions
171 gregbook => source code for PNG reading and writing, from
172 Greg Roelofs' "PNG: The Definitive Guide",
174 msvctest => Builds and runs pngtest using a MSVC workspace
175 pngminus => Simple pnm2png and png2pnm programs
176 pngsuite => Test images
177 visupng => Contains a MSVC workspace for VisualPng
178 projects => Contains project files and workspaces for building DLL
179 beos => Contains a Beos workspace for building libpng
180 c5builder => Contains a Borland workspace for building libpng
182 visualc6 => Contains a Microsoft Visual C++ (MSVC) workspace
183 for building libpng and zlib
184 netware.txt => Contains instructions for downloading a set of
185 project files for building libpng and zlib on
187 wince.txt => Contains instructions for downloading a Microsoft
188 Visual C++ (Windows CD Toolkit) workspace for
189 building libpng and zlib on WindowsCE
190 scripts => Directory containing scripts for building libpng:
191 descrip.mms => VMS makefile for MMS or MMK
192 makefile.std => Generic UNIX makefile (cc, creates static libpng.a)
193 makefile.elf => Linux/ELF makefile symbol versioning,
194 gcc, creates libpng12.so.0.1.2.29)
195 makefile.linux => Linux/ELF makefile
196 (gcc, creates libpng12.so.0.1.2.29)
197 makefile.gcmmx => Linux/ELF makefile
198 (gcc, creates libpng12.so.0.1.2.29,
199 uses assembler code tuned for Intel MMX platform)
200 makefile.gcc => Generic makefile (gcc, creates static libpng.a)
201 makefile.knr => Archaic UNIX Makefile that converts files with
202 ansi2knr (Requires ansi2knr.c from
203 ftp://ftp.cs.wisc.edu/ghost)
204 makefile.aix => AIX makefile
205 makefile.cygwin => Cygwin/gcc makefile
206 makefile.darwin => Darwin makefile
207 makefile.dec => DEC Alpha UNIX makefile
208 makefile.freebsd => FreeBSD makefile
209 makefile.hpgcc => HPUX makefile using gcc
210 makefile.hpux => HPUX (10.20 and 11.00) makefile
211 makefile.hp64 => HPUX (10.20 and 11.00) makefile, 64 bit
212 makefile.ibmc => IBM C/C++ version 3.x for Win32 and OS/2 (static)
213 makefile.intel => Intel C/C++ version 4.0 and later
214 libpng.icc => Project file, IBM VisualAge/C++ 4.0 or later
215 makefile.netbsd => NetBSD/cc makefile, PNGGCCRD, makes libpng.so.
216 makefile.ne12bsd => NetBSD/cc makefile, PNGGCCRD, makes libpng12.so
217 makefile.openbsd => OpenBSD makefile
218 makefile.sgi => Silicon Graphics IRIX (cc, creates static lib)
219 makefile.sggcc => Silicon Graphics
220 (gcc, creates libpng12.so.0.1.2.29)
221 makefile.sunos => Sun makefile
222 makefile.solaris => Solaris 2.X makefile
223 (gcc, creates libpng12.so.0.1.2.29)
224 makefile.so9 => Solaris 9 makefile
225 (gcc, creates libpng12.so.0.1.2.29)
226 makefile.32sunu => Sun Ultra 32-bit makefile
227 makefile.64sunu => Sun Ultra 64-bit makefile
228 makefile.sco => For SCO OSr5 ELF and Unixware 7 with Native cc
229 makefile.mips => MIPS makefile
230 makefile.acorn => Acorn makefile
231 makefile.amiga => Amiga makefile
232 smakefile.ppc => AMIGA smakefile for SAS C V6.58/7.00 PPC
233 compiler (Requires SCOPTIONS, copied from
234 scripts/SCOPTIONS.ppc)
235 makefile.atari => Atari makefile
236 makefile.beos => BEOS makefile for X86
237 makefile.bor => Borland makefile (uses bcc)
238 makefile.bc32 => 32-bit Borland C++ (all modules compiled in C mode)
239 makefile.tc3 => Turbo C 3.0 makefile
240 makefile.dj2 => DJGPP 2 makefile
241 makefile.msc => Microsoft C makefile
242 makefile.vcawin32=> makefile for Microsoft Visual C++ 5.0 and
243 later (uses assembler code tuned for Intel MMX
245 makefile.vcwin32 => makefile for Microsoft Visual C++ 4.0 and
246 later (does not use assembler code)
247 makefile.os2 => OS/2 Makefile (gcc and emx, requires pngos2.def)
248 pngos2.def => OS/2 module definition file used by makefile.os2
249 makefile.watcom => Watcom 10a+ Makefile, 32-bit flat memory model
250 makevms.com => VMS build script
251 SCOPTIONS.ppc => Used with smakefile.ppc
253 Good luck, and happy coding.
255 -Glenn Randers-Pehrson (current maintainer)
256 Internet: glennrp at users.sourceforge.net
258 -Andreas Eric Dilger (former maintainer, 1996-1997)
259 Internet: adilger at enel.ucalgary.ca
260 Web: http://members.shaw.ca/adilger/
262 -Guy Eric Schalnat (original author and former maintainer, 1995-1996)
263 (formerly of Group 42, Inc)
264 Internet: gschal at infinet.com
projects / opencv / blob