TODO - list of things to do for libpng:

Final bug fixes.
Fix problem with C++ and EXTERN "C".
Better C++ wrapper/full C++ implementation?
Keep up with public chunks.
cHRM transformation.
Support for application-defined chunk handlers.
Improve setjmp/longjmp usage or remove it in favor of returning error codes.
High-level API for reading images.
Add "grayscale->palette" transformation and "palette->grayscale" detection.
Improved dithering.
Multi-lingual error and warning message support.
Complete sRGB transformation (presently it simply uses gamma=0.45455).
Man pages for function calls.
Better documentation.
Better filter selection
   (counting huffman bits/precompression?  filter inertia?  filter costs?).
Histogram creation.
Text conversion between different code pages (Latin-1 -> Mac and DOS).
Improve API by hiding the info_ptr.
Make a no-floating-point version.