I've been using png for pretty much all my images, but it gets annoying when you start dealing with layered images (such as masks for colour tinting a sprite, or shared colour+normal maps, or images defining level layouts). It'd be nice to start using proper layered images directly and skip an extra export step in my toolchain.
Seems to be supported by Paint.NET, Gimp and Pinta, so that's all the platforms I care about covered too.
Anyone used or is using this? It looks like a nice sane format so I might try and write a little lib to open the files in java. Alternatively, is anyone using any other alternatives for layered, cross platform images?