Detecting image equality at different resolutions

Question

I\'m trying to build a script to go through my original, high-res photos and replace the old, low-res ones I uploaded to Flickr before I had a pro account.

For many of t

Answer 1

Compute the normalized color histogram of both images and compare them using some method (histogram intersection, for example - see the link above). Note the normalized histogram is needed because the images present different resolutions. If the images are so dissimilar, they are not the same picture. But if they are similar, you have one of these two cases: (i) they are the same picture or (ii) they are different pictures but present similar global color distributions.

For case (ii), split the images and rectangular tiles and repeat the process, comparing correspondent tiles. You are trying to account for local properties of the image. Rank the results and pick the best match.