AC_ARG_WITH(system-pnglib,
	[  --with-system-pnglib       use installed pnglib library])

AC_ARG_WITH(pnglib_libdir,
[  --with-pnglib-libdir=DIR
                          Specify directory where the png library (libpng.a) resides.])

AC_ARG_WITH(pnglib_include,
[  --with-pnglib-include=DIR
                          Specify the pnglib header files location.])
