Facebook has taken some flak recently for removing photos of women breastfeeding and gay people kissing (it says these were mistakes), but now it's using its passion for weeding out offensive photos for good. Today Facebook announced it's the first site to start using a new technology that can search through databases and locate illegal images, even if they've been cropped an altered.

Microsoft developed the technology, which is called PhotoDNA, in 2009 and donated it to the National Center for Missing & Exploited Children. Facebook is currently using PhotoDNA to find child pornography stored among the 200 million images uploaded by users per day. Ernie Allen, chief executive of the National Center for Missing & Exploited Children, told the New York Times:

"Our hope and belief is that Facebook will be just the first of many companies to use what has proven to be highly effective technology. Online services are going to become a hostile place for child pornographers and pedophiles."

Facebook will focus on searching for images of children under 12, to root out the "worst of the worst." (Supposedly it won't be used to identify adult pornography, just images of minors.) The technology is explained in the Microsoft video above. The company says right now PhotoDNA can search for about 10,000 images provided by the National Center for Missing & Exploited Children. Sadly that's just a tiny fraction of the child pornography floating around the web. Since 2002, the organization has collected 48 million images and videos.

Still, PhotoDNA should help Facebook identify far more of these photos, since previously it relied on user-submitted reports. Law enforcement officials are also interested in using PhotoDNA in cases against pedophiles by matching the physical setting to find evidence of multiple crimes. Presumably in the future the technology will be misused in some way (removing shots of homosexuals kissing just got easier!), but for now it looks like it could make a significant dent in the amount of child pornography being passed around online.

Facebook's New Way To Combat Child Pornography [NYT]