Whether or not Facebook acquires facial recognition services provider Face.com, as rumors say it will, the persistence of the speculation calls attention to the expanding use of the technology in social applications.
Face.com's first app, Photo Finder, allowed Facebook users to search for photos of themselves that others had uploaded. Photo Tagger, which suggests names for people pictured, launched in November 2009. Just over a year later, Facebook licensed Face.com's technology to begin suggesting friends for users to tag.
If Facebook acquires Face.com, it could be motivated by a desire to own, rather than license Face.com's technology or to "acqui-hire" the app maker's team, industry watchers said. Either way, a purchase would seem to point to increased interest in facial recognition.
The technology is now in a "sweet spot," benefitting from better computer visualization algorithms and expanding numbers of people sharing photographs, according to Brian Blau, an analyst at Gartner.
"That has to do with the capabilities of the devices and the critical mass of people putting their faces online," Blau said.
The so-called "computer vision" technology that empowers computers to recognize faces has only recently gotten good enough that consumer-facing companies like Facebook, Apple and Google can support it, according to Apu Kapadia, a computer scientist at the University of Illinois, whose research includes digital privacy issues.
Google's Picasa began offering facial recognition in 2008, and Google+ also offers the feature. Apple's 2009 version of iPhoto first supported the technology.
Mainstream adoption also means that the technology will improve ever more rapidly.
"The model gets better and better, usually, as you feed more data into it," Kapadia said.
Users upload 300 million photos to Facebook, the company claimed in its pre-IPO paperwork.
Facebook users can choose not to have their name used as a suggested tag. But they can't turn off the facial recognition technology.
Privacy advocates fear that the social network's immense collection of photographs identifying many of its 900 billion users will leave users exposed to unwanted identification by law enforcement groups, identity thieves or even stalkers. Many of these concerns were laid out in comments to the U.S. Federal Trade Commission when the body hosted a workshop on facial recognition last December.
As tagging photos becomes easier and more common, the most immediate effect is a cultural shift in what is private and what isn't. Kapadia said things we may be willing to share in small groups are now often shared with large groups via social networks. And the anonymity individuals once expected in crowds has been eroded.
"The way things are headed, it's going to be easier for people to tag you in photos, so you're going to be less and less anonymous in some ways when you're walking down the street or going to a party," Kapadia said.
Cameron Scott covers search, web services and privacy for The IDG News Service. Follow Cameron on Twitter at CScott_IDG.