APNG

Animated Portable Network Graphics (APNG) is a file format which extends the Portable Network Graphics (PNG) specification to permit animated images that work similarly to animated GIF files, while supporting images with a higher color depth and full alpha transparency not available for GIFs. It also retains backward compatibility with non-animated PNG files. It was developed by the Mozilla Foundation in 2004. The first frame of an APNG file is stored as a normal PNG stream, so most standard PNG decoders are able to display the first frame of an APNG file. The frame speed data and all of the subsequent frames are stored in extra chunks (as provided for by the original PNG specification). APNG competed with Multiple-image Network Graphics (MNG), a comprehensive format for bitmapped animations which was created in 2001 by the same team as PNG, which is now obsolete. APNG's advantages over MNG are its smaller library size and its compatibility with older PNG implementations.