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Re: Compare images in Cocoa




On Oct 30, 2008, at 11:21 PM, Pierce Freeman wrote:

Hi everyone. I am wondering if there is some way to compare two images in
Cocoa, and then somehow spit out a percent of how similar they are. The only
way I could think of is comparing every pixel, but this seems like it would
take a long time, and even so I have no idea how to go about doing that.


Thanks for your help.

You don't say what you want this number for. Are you trying to tell if two images of faces are of the same person? Two images of buildings are of the same building? Two images have similar colors in them?


FWIW, iterating over all the pixels in an image and doing some kind of simple math on the pixel values will not be very time-consuming. There are lots of Photoshop filters that do this and are very fast.

One thought that comes to mind is to calculate the histogram for the two images and compare them. This could give a kind of simplistic % difference.


-- Brian Stern email@hidden



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 >Compare images in Cocoa (From: Pierce Freeman <email@hidden>)



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