Image Analysis?

Sup /prog/

I have a problem whereby I need to identify (with any degree of accuracy) whether or not an image is a resized version of another image. ``Resize'' is defined as a constant aspect-ratio downscale with (hopefully) a cubic sampling. I haven't been able to turn up any reasonable material on image analysis, which means I'm left to my own devices.

I think one viable option might be to consider the proportions of colors within the image. A ``color'', for my purposes, is defined as a set of three ranges (one range for each RGB channel). The algorithm would essentially go through each pixel, keeping a tally of how many of each color there are, then sort by occurance. Two images with similar proportions of the top 5 colors or so are flagged as identical.

The colors would necessarily be ranges because of the cubic sampling -- since one of the images is a downscaled version of another, the set of colors from the two images won't be the same. A pathological example: a large image consisting of alternating white and black pixels gets downscaled, the resultant image has gray -- a color which was not present in the original image.

I had some other weird ideas, like taking the diagonals, downscale one at runtime to fit the other, then compare the deltas.

I dunno. Anyone have ideas/suggestions/links?

>>43
Meh, I think there's plenty of intelligent people on /prog/ who can and will talk about programming-related subjects. The problem is that people rarely start intelligence-provoking threads; the majority of the threads are just shit. And shit breeds shit.

I've always felt that, if a question is phrased in a thought-provoking manner or is a new, interesting question, /prog/ will respond accordingly. If you look at it empirically, most people who ask questions in the OP get their questions answered, albeit with a lot of extra noise mixed in.

Anyway, I don't know what the fuck I'm blabbering about. hax my anus.