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Automatic scaling doesn't work very well. You can find numerous design blogs showing you in great detail why it looks slightly shoddy if you scale from 512x512 down to 128x128 or 64x64, and how below 64x64 you just get into illegibility. For your app to look great you need hand tweaked assets for most resolutions. http://mrgan.tumblr.com/post/708404794/ios-app-icon-sizes http://bjango.com/articles/designingforretina2/

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No, you don't understand. Of course, automatic scaling doesn't work.

Prepare two images - 512x512 and 32x32. Scale first one down to 32x32, subtract it from the second one and this will yield a arithmetic, per-pixel difference. Compress it. Now store 512x512 image and the compressed diff with an app. With these two, you will then be able to recreate original 32x32 (by scaling down 512x512 and applying the diff). And I am making an (educated) guess here that the compressed diff will take less space than the actual 32x32 image.

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