So I want to incorporate GameCenter achievements in my game, but I have to supply images for each achievement for display in the GameCenter app. Apple isn't really clear about the required size. I've read online that they demand 512px images, but then they scale them down to something like 32px which makes it all blurry and/or pixelated.

There must be a better method. I've seen several apps now with crisp, clear achievement images. How do they do this? Thanks.