1This demonstrates the use of PNG_USER_CONFIG and pngusr.h
 2
 3The makefile builds a minimal write-only encoder with embedded libpng
 4and zlib.
 5
 6Specify the location of the zlib source (1.2.1 or later) as ZLIBSRC
 7on the make command line.
 8
 9If you prefer to use the shared libraries, go to contrib/pngminus
10and build the pnm2png application there.