Commtouch claims defense against image-based spam.

Of late, spammers have been bundling their spam into images, insulating them from text-based spam filters. In effect, creating captchas to block automated spam filters. The images are even varied slightly to make them harder to detect.

Now, Commtouch, of Mountain View, CA, says they've developed technology which they call Recurrent Pattern Detection which is designed to look for recurring patterns in images which may identify them as spam.

Details on the alogorithm are sketchy, but it sounds like it might be just a basic image-matching algorithm.

For more details, see their press release and Globe Online article Commtouch claims to have beaten image-based spam.