pngcheck version 2.0.0 of 17 July 2005

I believe this is the fifth or sixth major release since version 1.98,
which is when I took over maintenance of pngcheck from Alexander Lehmann
and Andreas Dilger.  Enhancements since 1.98 include:  zlib capability
(to test the compressed stream and, optionally, to print out the image's
row filters); support for all known PNG chunks; support for JNG images
conforming to Draft 70 or later (or maybe the 1.0 spec?); partial support
for MNG streams conforming to the 1.0 specification; extended support for
printing palettes (includes transparency info and histograms now); info
on the compression factor of the image (expressed as a percentage, where
0% is no compression and 100% would be total compression--note that this
can be negative since it counts PNG's chunk overhead against the compression
factor); and support for MSVC compilation under Win32.  It also contains
many fixes, including ones from Tom Lane, Glenn Randers-Pehrson, Tom Zerucha,
Paul Matzke, Darren Salt, John Bowler, and others.

The README for 1.99.3 said this:

   Improved ("finished") support for MNG is coming relatively soon, at
   which point the version number will finally reach 2.0, but I won't
   make any promises as to when.  Support for EBCDIC-based systems will
   show up someday, too.  DOS/Win32 wildcards should already be supported,
   at least in the distributed binaries.

Then five years passed...  (I blame the kids.)  Good thing there were no
promises, eh?  Anyway, here's version 2.0.  MNG support is better but
still incomplete, contrary to the claim above, and there are still no
promises as to when it will be finished (though it will happen eventually
...probably).  No, the version got bumped because (1) zlib checking is now
turned on regardless of verbosity level, which makes pngcheck slower but
far more useful as an integrity-tester, and (2) who takes bugfix/patchlevel
version-increments seriously?  (OK, there's the Linux kernel, but that's
another matter entirely...)

And as for finishing MNG support, note that sample MNGs with not-yet-supported
chunks in them tend to be a good motivator.  (Thank GraalOnline's emoticons
for TERM support and Bob Friesenhahn's test stream for fixed SAVE support,
for example.)

As always, see http://www.libpng.org/pub/png/apps/pngcheck.html for updates.

Greg Roelofs
http://pobox.com/~newt/greg_contact.html
