On 12/5/06, Alphax (Wikipedia email) alphasigmax@gmail.com wrote:
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/?
The subject you really want to search is "image indexing" and it's a surprisingly immature area.
A simple exact match hash will be kept by the later image storage system. It would be useful for some thing (detecting exact digital duplicates), but wouldn't have helped with my image (which was a copy of the image page thumbnail).