>>galley+(OP)
Hash yes, fingerprint maybe no. Maybe I'm using the term incorrectly here, but I think of fingerprint like a lossy hash. Like one way of doing this would be to resize the image to, say, 8 by 8, and quantize it to say, 16 colors. So the fingerprint size is 8
84 bits=32 bytes. Tiny changes aren't likely to change the fingerprint. You'd probably have to do something a little more clever so as not to get too many false positives though. Or once you get a hit, do a deeper comparison.