PHILADELPHIA (CBS) - Privacy experts in Philadelphia and elsewhere are warning Facebook users that the social networking site is expanding its use of facial recognition software, and they say users may want to go into their privacy settings to protect their images.

Facebook is using the software to make it easier to “tag” photos — that is, add the names of the people in the photos you post on the site.

A Facebook spokesman says users asked for ways to ease the photo tagging process, and most love it.

But it’s raising an old concern about Facebook.

The site automatically adds the auto-tagging without informing you, and it’s up to you to figure that out and opt out if it’s something you don’t want Facebook doing with your account.

“We don’t want Facebook making that decision for us,” says Rob D’Ovidio, a high-tech surveillance expert in Drexel University’s criminal justice program.

He says there are reasons that people might not want the feature:

“How are we assured that that data is not going to be applied for a totally different purpose, whether that’s a government agency, or a multinational corporation that’s using it for marketing purposes?”

D’Ovidio recommends opting out.

Reported by Pat Loeb, KYW Newsradio 1060