George Koller on thu 30 aug 07
Now that I'm thinking about this::....
Just went back into my bookmarks and found this site with a list and feature list of different software involved with building images from images, here it is:
(caution:: the table is somewhat old and was probably constructed by one of the companies with a product to sell, but then you can also relax because at least several of the companies have free demo versions)
I know from first hand testing that several of the packages work just fine and gave me fascinating / brain teasing results... comparing billions of bits for color matches is great work for the many many under-employed processors out there otherwise idling away their day waiting to spend 1% of their power to process an email.