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arm/12-Mar-20154 KiB

autogen.sh12-Mar-20157.8 KiB

CHANGES12-Mar-2015240.6 KiB

CleanSpec.mk12-Mar-20152.2 KiB

CMakeLists.txt12-Mar-201512.8 KiB

compile12-Mar-20157.2 KiB

config.guess12-Mar-201544.7 KiB

config.h.in12-Mar-20153 KiB

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configure12-Mar-2015447.2 KiB

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example.c12-Mar-201539.3 KiB

INSTALL12-Mar-20156 KiB

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libpng-config.in12-Mar-20152.3 KiB

libpng-manual.txt12-Mar-2015227.3 KiB

libpng.312-Mar-2015273.4 KiB



LICENSE12-Mar-20154.1 KiB

ltmain.sh12-Mar-2015276.8 KiB

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Makefile.in12-Mar-201587 KiB

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png.512-Mar-20152.4 KiB

png.c12-Mar-2015145.9 KiB

png.h12-Mar-2015142.5 KiB

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pngconf.h12-Mar-201522.8 KiB

pngdebug.h12-Mar-20155.2 KiB

pngerror.c12-Mar-201528.4 KiB

pngget.c12-Mar-201532 KiB

pnginfo.h12-Mar-201512.1 KiB

pnglibconf.h12-Mar-20157.1 KiB

pngmem.c12-Mar-20158.1 KiB

pngnow.png12-Mar-20152 KiB

pngpread.c12-Mar-201535.5 KiB

pngpriv.h12-Mar-201579.7 KiB

pngread.c12-Mar-2015139.2 KiB

pngrio.c12-Mar-20154.4 KiB

pngrtran.c12-Mar-2015163.8 KiB

pngrutil.c12-Mar-2015139.5 KiB

pngset.c12-Mar-201545.6 KiB

pngstruct.h12-Mar-201521.4 KiB

pngtest.c12-Mar-201556.8 KiB

pngtest.png12-Mar-20158.5 KiB

pngtrans.c12-Mar-201524.4 KiB



pngwio.c12-Mar-20155.5 KiB

pngwrite.c12-Mar-201575.8 KiB

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pngwutil.c12-Mar-201586.9 KiB

projects/12-Mar-20154 KiB

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scripts/12-Mar-20154 KiB

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tests/12-Mar-20154 KiB

TODO12-Mar-20151.2 KiB



1README for libpng version 1.6.10 - March 6, 2014 (shared library 16.0)
2See the note about version numbers near the top of png.h
4See INSTALL for instructions on how to install libpng.
6Libpng comes in several distribution formats.  Get libpng-*.tar.gz or
7libpng-*.tar.xz or if you want UNIX-style line endings in the text files,
8or lpng*.7z or lpng*.zip if you want DOS-style line endings.
10Version 0.89 was the first official release of libpng.  Don't let the
11fact that it's the first release fool you.  The libpng library has been in
12extensive use and testing since mid-1995.  By late 1997 it had
13finally gotten to the stage where there hadn't been significant
14changes to the API in some time, and people have a bad feeling about
15libraries with versions < 1.0.  Version 1.0.0 was released in
16March 1998.
19Note that some of the changes to the png_info structure render this
20version of the library binary incompatible with libpng-0.89 or
21earlier versions if you are using a shared library.  The type of the
22"filler" parameter for png_set_filler() has changed from png_byte to
23png_uint_32, which will affect shared-library applications that use
24this function.
26To avoid problems with changes to the internals of png_info_struct,
27new APIs have been made available in 0.95 to avoid direct application
28access to info_ptr.  These functions are the png_set_<chunk> and
29png_get_<chunk> functions.  These functions should be used when
30accessing/storing the info_struct data, rather than manipulating it
31directly, to avoid such problems in the future.
33It is important to note that the APIs do not make current programs
34that access the info struct directly incompatible with the new
35library.  However, it is strongly suggested that new programs use
36the new APIs (as shown in example.c and pngtest.c), and older programs
37be converted to the new format, to facilitate upgrades in the future.
40Additions since 0.90 include the ability to compile libpng as a
41Windows DLL, and new APIs for accessing data in the info struct.
42Experimental functions include the ability to set weighting and cost
43factors for row filter selection, direct reads of integers from buffers
44on big-endian processors that support misaligned data access, faster
45methods of doing alpha composition, and more accurate 16->8 bit color
48The additions since 0.89 include the ability to read from a PNG stream
49which has had some (or all) of the signature bytes read by the calling
50application.  This also allows the reading of embedded PNG streams that
51do not have the PNG file signature.  As well, it is now possible to set
52the library action on the detection of chunk CRC errors.  It is possible
53to set different actions based on whether the CRC error occurred in a
54critical or an ancillary chunk.
56The changes made to the library, and bugs fixed are based on discussions
57on the PNG-implement mailing list and not on material submitted
58privately to Guy, Andreas, or Glenn.  They will forward any good
59suggestions to the list.
61For a detailed description on using libpng, read libpng-manual.txt.  For
62examples of libpng in a program, see example.c and pngtest.c.  For usage
63information and restrictions (what little they are) on libpng, see
64png.h.  For a description on using zlib (the compression library used by
65libpng) and zlib's restrictions, see zlib.h
67I have included a general makefile, as well as several machine and
68compiler specific ones, but you may have to modify one for your own needs.
70You should use zlib 1.0.4 or later to run this, but it MAY work with
71versions as old as zlib 0.95.  Even so, there are bugs in older zlib
72versions which can cause the output of invalid compression streams for
73some images.  You will definitely need zlib 1.0.4 or later if you are
74taking advantage of the MS-DOS "far" structure allocation for the small
75and medium memory models.  You should also note that zlib is a
76compression library that is useful for more things than just PNG files.
77You can use zlib as a drop-in replacement for fread() and fwrite() if
78you are so inclined.
80zlib should be available at the same place that libpng is, or at
82You may also want a copy of the PNG specification.  It is available
83as an RFC, a W3C Recommendation, and an ISO/IEC Standard.  You can find
84these at
86This code is currently being archived at in the
87[DOWNLOAD] area, and at  If you can't find it
88in any of those places, e-mail me, and I'll help you find it.
90If you have any code changes, requests, problems, etc., please e-mail
91them to me.  Also, I'd appreciate any make files or project files,
92and any modifications you needed to make to get libpng to compile,
93along with a #define variable to tell what compiler/system you are on.
94If you needed to add transformations to libpng, or wish libpng would
95provide the image in a different way, drop me a note (and code, if
96possible), so I can consider supporting the transformation.
97Finally, if you get any warning messages when compiling libpng
98(note: not zlib), and they are easy to fix, I'd appreciate the
99fix.  Please mention "libpng" somewhere in the subject line.  Thanks.
101This release was created and will be supported by myself (of course
102based in a large way on Guy's and Andreas' earlier work), and the PNG
103development group.
105Send comments/corrections/commendations to png-mng-implement at (subscription required; visit
108to subscribe) or to glennrp at
110You can't reach Guy, the original libpng author, at the addresses
111given in previous versions of this document.  He and Andreas will
112read mail addressed to the png-implement list, however.
114Please do not send general questions about PNG.  Send them to
115png-mng-misc at (subscription required; visit
116 to
117subscribe).  If you have a question about something
118in the PNG specification that is related to using libpng, send it
119to me.  Send me any questions that start with "I was using libpng,
120and ...".  If in doubt, send questions to me.  I'll bounce them
121to others, if necessary.
123Please do not send suggestions on how to change PNG.  We have
124been discussing PNG for nineteen years now, and it is official and
125finished.  If you have suggestions for libpng, however, I'll
126gladly listen.  Even if your suggestion is not used immediately,
127it may be used later.
129Files in this distribution:
131      ANNOUNCE      =>  Announcement of this version, with recent changes
132      CHANGES       =>  Description of changes between libpng versions
133      KNOWNBUG      =>  List of known bugs and deficiencies
134      LICENSE       =>  License to use and redistribute libpng
135      README        =>  This file
136      TODO          =>  Things not implemented in the current library
137      Y2KINFO       =>  Statement of Y2K compliance
138      example.c     =>  Example code for using libpng functions
139      libpng.3      =>  manual page for libpng (includes libpng-manual.txt)
140      libpng-manual.txt  =>  Description of libpng and its functions
141      libpngpf.3    =>  manual page for libpng's private functions
142      png.5         =>  manual page for the PNG format
143      png.c         =>  Basic interface functions common to library
144      png.h         =>  Library function and interface declarations (public)
145      pngpriv.h     =>  Library function and interface declarations (private)
146      pngconf.h     =>  System specific library configuration (public)
147      pngstruct.h   =>  png_struct declaration (private)
148      pnginfo.h     =>  png_info struct declaration (private)
149      pngdebug.h    =>  debugging macros (private)
150      pngerror.c    =>  Error/warning message I/O functions
151      pngget.c      =>  Functions for retrieving info from struct
152      pngmem.c      =>  Memory handling functions
153      pngbar.png    =>  PNG logo, 88x31
154      pngnow.png    =>  PNG logo, 98x31
155      pngpread.c    =>  Progressive reading functions
156      pngread.c     =>  Read data/helper high-level functions
157      pngrio.c      =>  Lowest-level data read I/O functions
158      pngrtran.c    =>  Read data transformation functions
159      pngrutil.c    =>  Read data utility functions
160      pngset.c      =>  Functions for storing data into the info_struct
161      pngtest.c     =>  Library test program
162      pngtest.png   =>  Library test sample image
163      pngtrans.c    =>  Common data transformation functions
164      pngwio.c      =>  Lowest-level write I/O functions
165      pngwrite.c    =>  High-level write functions
166      pngwtran.c    =>  Write data transformations
167      pngwutil.c    =>  Write utility functions
168      arm           =>  Contains optimized code for the ARM platform
169      contrib       =>  Contributions
170       examples         =>  Example programs
171       gregbook         =>  source code for PNG reading and writing, from
172                            Greg Roelofs' "PNG: The Definitive Guide",
173                            O'Reilly, 1999
174       libtests         =>  Test programs
175       pngminim         =>  Minimal decoder, encoder, and progressive decoder
176                            programs demonstrating use of pngusr.dfa
177       pngminus         =>  Simple pnm2png and png2pnm programs
178       pngsuite         =>  Test images
179       tools            =>  Various tools
180       visupng      =>  Contains a MSVC workspace for VisualPng
181      projects      =>  Contains project files and workspaces for
182                        building a DLL
183       owatcom          =>  Contains a WATCOM project for building libpng
184       visualc71        =>  Contains a Microsoft Visual C++ (MSVC)
185                            workspace for building libpng and zlib
186       vstudio          =>  Contains a Microsoft Visual C++ (MSVC)
187                            workspace for building libpng and zlib
188      scripts       =>  Directory containing scripts for building libpng:
189                            (see scripts/README.txt for the list of scripts)
191Good luck, and happy coding.
193-Glenn Randers-Pehrson (current maintainer, since 1998)
194 Internet: glennrp at
196-Andreas Eric Dilger (former maintainer, 1996-1997)
197 Internet: adilger at
198 Web:
200-Guy Eric Schalnat (original author and former maintainer, 1995-1996)
201 (formerly of Group 42, Inc)
202 Internet: gschal at