Messagelabs made a big deal of their option of using First 4 Internet's Image Composition Analysis tool to detect pornographic images. Is anyone in the open source world working on something similar.
Not that I'm aware of. Nor am I particularly impressed with the First 4 tool. It seems to operate mostly by detecting what percentage of an image is "skintone", leading to FPs on things like pictures of babies.
http://www.computerworld.com/securitytopics/security/story/0,10801,80431p2,00.html
The reviewer felt that a out of 100 hits, 9 FPs was acceptable.. In SA terms that's an S/O of 0.91.. While that's not bad, it's not exactly impressive either, particularly for something that's likely to be CPU intensive. The article doesn't describe in detail what the FN rate is, only uses vague terms.. but it doesn't sound very good either.
They also excused FN's on messages containing images made out of several small images. So right out of the box there's an evasion technique that spammers can use to avoid this tool with ease.
Really, if you're not using razor, you should. It's a better general-purpose solution for this problem, and likely to run at about the same speed.
Razor is able to spam-classify individual mime sections of messages based on reported SHA hashes. This way if a spam with that image is reported any other spam with that same mime section will hit.
This will also help with the image-based pill spams too, not just the porn ones.
