Are there any open source sprite format?

PNG just plainly sucks. I has no support for animations, timing or delta compression and sequence names. Also, PNG is slow at random access (you have to decompress image before use). Proprietary formats (like Diablo 2 DCC) are much better, but highly specialized for their games: some have no true color, other have no directions.

>>68
PNG is glorious open source grade
That explains why it sucks and uses primitive LZ77 (developed by two stupid jews), instead of much cooler LZW.