MENLO PARK, Calif. (AP) — When Matt King first got on Facebook eight years ago, the blind engineer had to weigh whether it was worth spending an entire Saturday morning checking whether a friend of his was actually in his friend list. Such were the tools at the time for the visually impaired — almost nonexistent.

Today, thanks to text-to-audio software, it just takes a few seconds for him to accomplish the same task. And because of a new face recognition service the social network is rolling out Tuesday, he can now learn which friends are in photos, even those who haven't been tagged by anothe...