** PNMTOPNG / PNGTOPNM
** version 2.39 - 12 November 2005
-- [start of Greg Roelofs commentary] --
This is another in a set of "official" bug-fix/enhancement releases. I sort of took over maintenance of this package while Willem was on an extended bike trip several years ago, and for now I'm continuing with periodic, small updates. (The code really should be rewritten to avoid directly messing with libpng's internal structures, but I haven't yet found time to do that.)
Brief changelog:
2.39 - fixed alphas_of_color[] buffer-overrun bug; incorporated Makefile
patch from Martin Mokrejs and updated or removed other makefiles;
incorporated zlib-strategy patch from Cosmin Truta; incorporated
significant-bits patch from Sascha Demetrio; cleaned up read_text()
function and fixed memleak; fixed several potential allocation-
overflow bugs (based on Debian/Alan Cox security patch); updated
man pages
2.38 - forced explicit binary mode on stdin/stdout for DOS-like OSes;
added same (optional) support for warning-level return codes to
pngtopnm (see 2.37.5 above); plugged some memory leaks; documented
palette-remapping code better; added support for custom (ordered)
palette (new -palette option); added some checks for malloc()
failure; extended syntax of text-comment files by allowing blank
lines and keywords on separate lines from main text (tenthumbs at
cybernex.net); abandoned silly "ultra-minor" version number
2.37.6 - fixed a bug in -background handling for low-bit-depth grayscale
images; renamed version.h to pnmtopng_version.h
2.37.5 - fixed a bug in -transparent handling (pnmtopng no longer chooses
an approximate color if the specified one isn't present); quieted
a gcc warning in the non-16-bit version; added optional support
for warning-level return codes (define PNMTOPNG_WARNING_LEVEL 2
to enable) to pnmtopng
2.37.4 - fixed a bug that caused 16-shade grayscale images to be written
as 8-bit grayscale instead of (smaller) 4-bit colormapped images
(bug report, analysis and fix by Rafal Rzeczkowski); added support
for the new/upcoming pbmplus release (based on 1999-11-28 beta).
2.37.3 - fixed a minor bug with respect to error exits; generally cleaner
error exits (close files, etc.)
2.37.2 - fixed gcc "clobber" warnings; under Solaris, they resulted in
stack corruption even when there was no error in the image files
or libraries
2.37.1 - fixed rescaling bug with grayscale palettes; cleaned up Linux
makefile; cleaned up uninitialized-variable warnings
2.37 - (March 1998) never publicly released, partly because Willem had
hoped to quiet gcc's "<var> might be clobbered by `longjmp'"
-- [end of Greg Roelofs commentary] --
The utilities pnmtopng and pngtopnm are based on other pbm tools and require the libraries included in the pbmplus/netpbm package. Also required are the png library and the zlib compression library.
These can be found at:
ftp://ftp.simplesystems.org/pub/libpng/png/src/libpng-*
ftp://ftp.simplesystems.org/pub/libpng/png/src/zlib-*
ftp://ftp.x.org/contrib/utilities/netpbm-1mar1994*
or see
http://www.libpng.org/pub/png/apps/pnmtopng.html
http://www.libpng.org/pub/png/libpng.html
http://zlib.net/
http://netpbm.sourceforge.net/
http://www.acme.com/software/pbmplus/ [update coming someday?]
To compile and install, a makefile is provided. Do check the directories where you have put the required libraries. Then either accommodate the makefile or make links from generic names (e.g., zlib) to version-specific directories (e.g., zlib-1.2.3), which is the recommended way.
For testing purposes, have a look at the test-set PngSuite.tar.gz, which contains a small test-image for every PNG color type and for most PNG chunk types. It can be found at:
http://www.schaik.com/pngsuite/pngsuite.html
ftp://ftp.simplesystems.org/pub/libpng/png/images/suite/
Other web pages with PNG images are at:
http://www.libpng.org/pub/png/png-textures.html
http://www.libpng.org/pub/png/pngs-img.html
http://www.libpng.org/pub/png/png-rgba32.html
http://www.libpng.org/pub/png/pngpic2.html
http://www.libpng.org/pub/png/png-gammatest.html
http://www.libpng.org/pub/png/png-colortest.html
http://www.libpng.org/pub/png/pngmisc.html#images
Alexander Lehmann <lehmann|usa.net>
Willem van Schaik <willem|schaik.com>
Greg Roelofs <newt|pobox.com>