"It stands to reason, therefore, that Facebook’s algorithm could scan any photo from any of its 800 million members, and recognize you if you’re in it. So, let

"It stands to reason, therefore, that Facebook’s algorithm could scan any photo from any of its 800 million members, and recognize you if you’re in it. So, let’s take that one logical step further. Imagine you take a photo of someone and upload it to Facebook’s servers. Facebook can analyze the photo and tag that person’s face." This could work for a mutual friend at a party. But if the face recognizer is given a low-quality subway photo and has 7 million people to choose from (NYC residents) of equal probability, the chance of current technology getting an accurate match is nil. The author may be a bit confused how Facebook's technology works. Yes, it recognizes faces, but it also eliminates ~99.9999% of members as possibilties by leveraging the social graph.