Image::PNG::Libpng is a Perl library for accessing the contents of PNG
 (Portable Network Graphics) images. Image::PNG::Libpng enables Perl to use the
 "libpng" library to read and write files in PNG format.
 .
 Image::PNG::Libpng consists of Perl subroutines which mirror the C functions in
 libpng, plus helper subroutines to make it easier to read and write PNG data in
 Perl.