“Automating the hunt for child pornographers”

New Scientist, April 6, 2011

“More recently, Microsoft teamed up with Hany Farid, a specialist in digital imagery at Dartmouth College in Hanover, New Hampshire, to develop a system called PhotoDNA. This can scan through millions of images being stored and viewed online, flagging those that match images held in NCMEC’s database. That’s useful because child pornographers repeatedly circulate old images as well as new ones. The idea is that PhotoDNA will help companies that unknowingly host illegal material to detect and purge it - and pass information to the police for investigation.”