Image comparison using Objective C

i am planning to create an application to com开发者_JS百科pare pill images if they were the same. Is there any source that i could use that detects colors, shape, size of the pill in the picture and compre if that picture is the same with the other picture of the same pill?

Regards, ZaldzBgz

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I know a good library for computer vision, not sure if it can help you. You can look at: OpenCV. It worked with iPhone