libpng

libpng is the official PNG reference library. It supports almost all PNG features, is extensible, and has been extensively tested for over 12 years.

libpng is available as ANSI C source code and requires zlib 1.0.4 or later (1.2.3 or 1.1.4 recommended due to potential security vulnerabilities in earlier versions). In addition to the main library sources, libpng includes the rpng, rpng2 and wpng demo programs, the pngminus demo program, a subset of Willem van Schaik's PngSuite test images, Willem's VisualPng demo program, and Intel's MMX-optimized routines for faster decoding on x86-class CPUs (currently for Microsoft Visual C++ and GNU C only; the two versions are equivalent aside from a thread-safety issue in the latter port).