TODO - list of things to do for libpng
add "grayscale->palette" transformation and "palette->grayscale" detection
improved dithering
multi-lingual error and warning message support
sPLT chunk handling
cHRM transformation
complete sRGB transformation (presently it simply uses gamma=0.45)
man pages for function calls
high-level API for reading images
final bug fixes
better documentation
better filter selection
(counting huffman bits/precompression? filter inertia? filter costs?)
optional palette creation
histogram creation
support for application-defined chunk handlers
keep up with public chunks
better C++ wrapper/full C++ implementation?
text conversion between different code pages (Latin-1 -> Mac and DOS)
