[QUOTE=Ashley] Comparing the "blade" enemy from Space Blaster, which is a 16 frame animation, it comes out:
144kb PNGCrushed as 16 separate files after export
126kb as a single sprite sheet
So that's a saving of about 12% in filesize. I agree there is a saving to be had, but while we're really stretched for time over loads of important features that don't yet exist at all, I'm not prepared to spend time on this for an "invisible" improvement while there are much-missed features like families. So maybe this can be done some time in future.[/QUOTE]
I got it down to 29kb here in a sprite sheet.
Oh and graphics cards still work in power of two. Just because they are able to load non-power of 2 images doesn't mean that's all it doing. Those blade images are getting padded by the graphics card to 128x128 because that's the next power of 2.
So making HTML5 games which don't have hardware acceleration, it's best to optimize as much as possible.