Package libpng

A library of functions for manipulating PNG image format files

http://www.libpng.org/pub/png/

The libpng package contains a library of functions for creating and
manipulating PNG (Portable Network Graphics) image format files. PNG
is a bit-mapped graphics format similar to the GIF format. PNG was
created to replace the GIF format, since GIF uses a patented data
compression algorithm.

Libpng should be installed if you need to manipulate PNG format image
files.

File Formats (Section 5)
png
PNG (Portable Network Graphics) is an extensible file format for the lossless, portable, well-compressed storage of raster images. PNG provides a patent-free...