I've searched around but I still don't really get which color modes you can and can't use with Cocos2D. The thing is that I have large images with only greyscale. Currently they are in 32bit png, but the quality is ofcourse exactly the same with 8bit greyscale.

Is there some way to use greyscale textures?

I looking for ways to both reduce storage size and texture memory usage. I tried using pvr compression but both 4 and 2 bit create too many artefacts. I also tried increase the texture dimensions and then scale them down on the phone. That went pretty well where 4bit became ok and 2bit somewhat ok. But I would really like better quality.

I haven't found a way to create 16bit png.

What happens when I load an 8bit png? Does it get converted and if so to what 16 or 32bit. I guess there is no true 24bit, correct?

Any suggestions?