I'm looking for some Free (preferably LGPL'd) image analysis/comparison libraries. The most important thing they should be able to do, is compare two different images and say if they're similar, with adjustable sensibility (i.e the higher the sensibility the more they have to look like each other to get a positive result) I'm thinking either C/++/# or eventually Python. So far the only solution I've come across is OpenCV, which is under the BSD license. I have yet to study how much of what I need is already implemented in the library, and what I may need to write myself, but I would really like to hear some other options before I start work on my project, so any opinions are welcome.
Comparing if two images are "similar" is an extremely hard, research-class problem. The approach you'd use will depend heavily on the types of similarities/differences that you are expecting between your images.
It will be hard to find something that works off-the-shelf, unless your comparison requirements are very specific.
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