Sizes For iPhone AddressBook Pictures?

I would like to programmatically generate contact pictures - something like what Gravatar does, although not ex开发者_StackOverflow中文版actly.

Are there size requirements on the generated images such that the contact picture will be full-screen when the user calls? Are there differences for these size requirements between iPhone 3/GS and iPhone 4?

I presume setting the pictures using the ABAddressBook API will provide no hurdles.

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In both cases - for iPhone 3 and iPhone 4 (with retina display) I wound up setting the image size to 640 x 960. When I set the profile picture to 320 x 480 for iPhone 3, the image didn't scale to fit the full screen.

So there you go!