** PNMTOPNG / PNGTOPNM
** version 2.37.5 - 24 October 2000

[This is a semi-official bug-fix and enhancement release; I sort of took over
 maintenance of this package while Willem was on an extended bike trip, and
 for now I'm continuing with periodic, small updates.  Version 2.37 (March
 1998) was never publicly released, partly because Willem had hoped to quiet
 gcc's "<var> might be clobbered by `longjmp'" warnings.  Those are fixed in
 2.37.2; under Solaris, they resulted in stack corruption even when there was
 no error in the image files or libraries.  Version 2.37.3 fixes a minor bug
 w.r.t. error exits and generally does cleaner error exits (close files, etc.)
 Version 2.37.4 fixes 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), and it supports the new/upcoming
 pbmplus release.  Version 2.37.5 fixes a bug in -transparent handling (pnmtopng
 no longer chooses an approximate color if the specified one isn't present) and
 quiets a gcc warning in the non-16-bit version.
 --Greg Roelofs]

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://swrinde.nde.swri.edu/pub/png/src/libpng-*
	ftp://swrinde.nde.swri.edu/pub/png/src/zlib-*
	ftp://ftp.x.org/contrib/utilities/netpbm-1mar1994*
or see
	http://www.libpng.org/pub/png/apps/pnmtopng.html
	http://netpbm.sourceforge.net/
	http://www.acme.com/software/pbmplus/		[update coming soon?]

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-1.1.3), 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://swrinde.nde.swri.edu/pub/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/pngpic2.html
	http://www.libpng.org/pub/png/colorcube/
	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>
