WASHINGTON - Imagine arriving at a hotel to be greeted by name, because a computer has analyzed your appearance as you approached the front door.

Or a salesman who IDs you and uses a psychological profile to nudge you to pay more for a car.

The day is coming when businesses, and others, will have those kinds of capabilities, says Alessandro Acquisti, a professor at Carnegie Mellon University who studies the positive and negative implications of facial recognition technology.

"Your phone -- or in some years your glasses and, in a few more, your contact lenses -- will tell you the name of that person at the party whose name you always forget," Acquisti said. "Or it will tell the stalker in the bar the address where you live."

However it is used, facial recognition is becoming a big business, with the potential to move far beyond such early applications as picking out Facebook friends in photos or helping cops nab crooks and terrorists.

In 2010, Maplewood-based 3M Co. paid nearly $1 billion for the California company Cogent, which develops a variety of identification systems, including iris and facial recognition technology. Another company, MorphoTrust USA, has a 150-person biometric facility in Bloomington.

"The next step in applications will be face-in-the-crowd -- identifying people at long distance," 3M Cogent marketing director Teresa Wu said. "That depends on the resolution of the cameras."

In 1990s pop culture trivia, Cheers was the bar where "everybody knows your name." In 21st-century America, with its social media, photo sharing and myriad cameras, you increasingly need only to appear in public to be recognized, even if you don't want to be.

Researchers say facial recognition technology is well on its way to supplanting fingerprints as the biometric identifier of choice. Eye and facial recognition technology are predicted to account for nearly $4 billion of the biometric industry's $11 billion in annual revenues by 2017. That same year, the number of cellphones and tablets equipped with facial recognition features is expected to swell to 665 million.

With recognition rates of 99.7 percent for well-lit, frontal photos, research and development has moved to identifying people without their knowledge -- whether in crowds or shadows or not looking directly at the camera.

The Orwellian potential of facial recognition has attracted the attention of lawmakers. When U.S. Sen. Al Franken of Minnesota looked at an explanation of how the FBI plans to use facial recognition technology to identify criminal suspects, he was surprised to find photos of political rallies.

"The FBI's own presentation of this technology shows it being used to identify people at a political rally," Franken told a deputy assistant FBI director at a recent congressional hearing. "It might be sending the wrong message, don't you think?"

In an interview last week, Franken, a Democrat, said he understands the need to thwart crime and terrorism. "The point I was making with the humor of understatement is that they were a little tone-deaf in the FBI showing what a magnificent tool this is."

The FBI says it has strict rules about how it uses facial recognition. It can only match photos of strangers against a national database of criminal mug shots. If the photos match the database, the FBI can only suggest a lead for local, state and federal investigators to follow. It cannot offer a positive identification.

Still, some see potential for abuse.

"The FBI shouldn't be in the business of monitoring demonstrations unless it has a cause, a tip, a reason," said Gregory Nojeim, senior counsel at the Center for Democracy and Technology. "Speech is easily chilled by that."

Policy debate

As chairman of the Senate Subcommittee on Privacy, Technology and the Law, Franken finds himself at the center of a larger national debate that increasingly pits information and technology against privacy and free speech.

On one side, you have people like Calhoun County, Ala., Sheriff Larry Amerson, who recently told Franken's subcommittee that "some advanced facial recognition in use today ... is as accurate as fingerprints, but results are obtained in seconds not hours."

On the other, you have people like Acquisti, who makes sure people understand how good technology can be put to bad uses. With fellow researchers Ralph Gross and Fred Stutzman, Acquisti proved you could take photos of anonymous students and use the Internet and over-the-counter facial recognition software to identify 30 percent of them before they finished filling out a three-page survey.

The researchers designed mathematical algorithms to extract sensitive personal data associated with the names of those identified. They also tested a cellphone face-recognition app that placed a name to a face in real time.

Meanwhile, Facebook uses facial recognition technology to support its popular tag suggestions feature, building a library of so-called "face prints" that privacy advocates say approaches a billion images and is second only to law enforcement.

Franken voiced concerns about how the social network might use those face prints besides as a tagging tool.

At a recent hearing, Franken asked Facebook's manager of privacy and public policy, Rob Sherman, if the company would rule out sharing its face print library with a third party. Sherman would not rule it out. A newly finalized settlement between Facebook and the Federal Trade Commission may or may not require Facebook to obtain permission before doing so.

Rapid advances

Still, roadblocks may be futile in slowing the spread of the technology.

At 3M Cogent, facial recognition is an expanding part of the business. Wu said the company's main customers work in law enforcement and national security.

"Technology is not depriving you of your privacy," she said. "It's how they use it."

Brian Martin, director of biometric research at MorphoTrust USA, said facial recognition is getting more accurate partly because cameras routinely come with higher and higher resolution, and the computers that process their images are getting stronger and faster.

"As all this comes together, I think you're going to see the error rates [for long-range, low light and obscured face recognition] cut in half," Martin said,

Legal experts don't believe photographing people in public places violates their constitutional rights. Nor does matching names to faces or storing and selling face prints.

And stringing together personal data from the connection of names to faces doesn't appear to violate the law, unless you steal someone's identity.

Up next in the commercial sphere could be digital signs with cameras attached that change advertisements as passersby and their personal shopping preferences are instantly identified.

In all of these scenarios, the concept of anonymity -- being a mere face in the crowd -- disintegrates.

Given time, Acquisti said, "there is no insurmountable technical challenge here." The challenge, he said, is finding the right balance between society's need for convenience and security and a person's need for privacy.

Jim Spencer • 202-383-6123