OpenCV / SURF How to generate a image hash / fingerprint / signature out of the descriptors?

Question

There are some topics here that are very helpful on how to find similar pictures.

What I want to do is to get a fingerprint of a picture and find the same picture on

Answer 1

It seems like GIST might be a more appropriate thing to use.

http://people.csail.mit.edu/torralba/code/spatialenvelope/ has MATLAB code.