When testing on iPod Touch, why are some images appearing huge? [duplicate]

This question already has answers here: Closed 12 y开发者_如何学运维ears ago.

Possible Duplicate:

Running app built in iOS4 on iOS 3.0, why is everything huge?

My images in my app are all 2x (or more) the size that they appear at. But for some reason, some of these images are appearing at their original size on the screen, when testing on a device, and so appear twice as large as they do in Interface Builder and on the simulator. And some are appearing at the size they should be.

Any ideas why this could be? My iPod Touch is 1st generation, so it's on 3.0 software.

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The app probably only includes double resolution images for the Retina Display, and they're not suffixed with "@2x" to indicate that they're double.