libpng: libpng (Portable Network Graphics library) libpng: libpng: PNG (Portable Network Graphics) is an extensible file format for the libpng: lossless, portable, well-compressed storage of raster images. PNG libpng: provides a patent-free replacement for GIF and can also replace many libpng: common uses of TIFF. Indexed-color, grayscale, and truecolor images libpng: are supported, plus an optional alpha channel. Sample depths range libpng: from 1 to 16 bits. libpng: libpng: libpng: