Facial recognition is an Internet feature which is growing in popularity. But while Facebook and Google (News - Alert) are expanding facial recognition options – researchers from Carnegie Mellon University are warning about the dangers it poses to privacy.

Several Carnegie Mellon researchers were able to ID some one-third of the subjects they tested, using a photo and facial-recognition technology from Google.

Alarmingly, one of lead researchers, Alessandro Acquisti, said that 27% of the time, using data from the subjects’ Facebook (News - Alert) profiles, they could correctly identify the first five digits of the subject’s Social Security numbers, according to a report from The Wall Street Journal.

“Two experiments demonstrated the ability of identifying strangers online (on a dating site where individuals protect their identities by using pseudonyms) and offline (in a public space), based on photos made publicly available on a social network site,” Acquisti wrote on his website. “A third … experiment illustrated the ability of inferring strangers' personal or sensitive information (their interests and Social Security numbers) from their faces, by combining face recognition, data mining algorithms, and statistical re-identification techniques.”

The results of the study raise many issues on “the future of privacy in an ‘augmented’ reality world in which online and offline data will seamlessly blend,” he said.

Their study also looked at the “convergence” of facial recognition, cloud computing and online social networks. They also came up with a mobile phone app “to recognize and then predict someone's sensitive personal data directly from their face in real time,” Acquisti said.

In addition, the researchers took images of college students using a webcam and compared the photos to images from Facebook profiles. The researchers were able to re-identify about one third of the students.

“Considering the technological trends in cloud computing, face recognition accuracy, and online self-disclosures, it is hard not to conclude that what today we presented as a proof-of-concept in our study, tomorrow may become as common as everyday's text-based search engine queries,” Acquisti predicts.

Earlier this year, Facebook implemented a facial recognition solution to help users better “tag (News - Alert)” photographs, according to TMCnet. The application can automatically recognize who is in the photo and tag them automatically, TMCnet explains.

As this study was being done, Google recently acquired Neven Vision, Riya, and PittPatt, Acquisti said. Google also deployed facial recognition into Picasa, Acquisti adds.

In addition, Apple (News - Alert) recently acquired Polar Rose, and deployed facial recognition into iPhoto, Acquisti said.

And Facebook has licensed Face.com to allow for automated tagging, according to Acquisti.