libpng's the official Portable Network Graphics (PNG) reference library (originally called pnglib). It's a platform-independent library that contains C functions for handling PNG images. It's developed by Guy Eric Schalnat, Andreas Dilger, Glenn Randers-Pehrson and others. libpng's dependent on zlib. The first version of the library was released on May 1, 1995. Released under the permissive free software licence used by zlib, libpng's free software.… (More on Libpng)