Magnus Manske wrote:
On 12/5/06, Gregory Maxwell gmaxwell@gmail.com wrote:
Someone came to me with an image they believed they obtained from commons but where unsure of exactly where they found it...
I was eventually able to locate the image, but it took a lot of work.
Had the image been deleted for copyright problems it would have been nearly impossible but it is in exactly that sort of situation which we may need the ability to find the image the most.
I have locally a database of image fingerprints (quantized color histograms) which could be used to locate images... it didn't work for this case because the image was newer than our last image backup (which was last year). It might be useful but it's not a complete solution.
A few hours ago, I wrote about adding an MD5 hash (or the like) to each image entry in the database. That would have helped finding the image in question as well, except if it has been altered.
A Google search for "image hash" gives 878 results (curses, [[Image:Hash function.svg]] shows up several times); surely there's a good one with a free implementation /somewhere/?