PurePNG allows PNG image files to be read and written using pure Python. PurePNG can read and write all PNG formats. PNG supports a generous variety of image formats: RGB or greyscale, with or without an alpha channel; and a choice of bit depths from 1, 2 or 4 (as long as you want greyscale or a pallete), 8, and 16 (but 16 bits is not allowed for palettes). A pixel can vary in size from 1 to 64 bits: 1/2/4/8/16/24/32/48/64. In addition a PNG file can be interlaced or not. An interlaced file allows an incrementally refined display of images being downloaded over slow links (yet it's not implemented in PurePNG for now).

PurePNG is written in pure Python(that's why it's called Pure).