Technology can be creepy. Remember that scene from the 2002 film "Minority Report"? John Anderton, played by Tom Cruise, walks through a hallway of digital screens that recognize him and shout advertisements: "John Anderton! You could use a Guinness right about now."

Something like that may not be too far off as digital billboards become more popular with advertisers. Research firm PQ Media predicted today that the market for digital out-of-home media in the U.S. would grow 11.2% to $2.43 billion this year. Globally, it's expected to expand 14.5% from 2007 to 2012. That makes digital billboards one of the fastest-growing advertising mediums around.

Companies are jostling to provide ways to make these digital screens even more effective. That includes TruMedia Technologies, a Florida company with research offices in Israel (company motto: "Every Face Counts"). TruMedia provides cameras and software for retail locations so the stores can show different on-screen ads depending on the gender and age of the person watching. The company says it soon will be able to also play different ads based on the race of the person watching.

Dr. Vicki Rabenou, chief measurement officer at TruMedia, presented the technology at the WebbyConnect conference in Dana Point on Friday. Here's how she says it works:

A device placed on, say, a supermarket shelf scans the face of the person standing in front of it. It determines whether the person is a man or a woman and sends that information to a digital screen nearby. The screen will play an ad for women's razors if a woman is watching, Jeeps if a man is watching, or Gap if both a man and woman are watching. "People are not even aware that they are being watched and monitored," Rabenou said.

The video analytics software to do this was developed for the Israeli homeland security department. It can determine, by facial clues, the gender and age of the faces it scans. By next year, the company says, the software will be able to ascertain ethnicity as well.

The device can also track how long people stand in front of a retail display, determining whether the display is clear. In an Israeli trial, it helped advertisers realize that a lot of men were buying Pampers on Thursday nights, so the company started a promotion that gave free razors to shoppers who bought two packs of Pampers. Rabenou said sales skyrocketed after the promotion. "Advertisers will use our systems as a real-life focus group," she said.

Of course, this may make some people a little concerned about the world turning into "Minority Report." Rabenou assured the crowd at WebbyConnect that TruMedia was "fully respectful of audience privacy," and added that "Big Brother is not watching."

The company doesn't track who specifically is watching the screens or standing in front of the displays, she said, just a person's gender and, as the technology develops, race and age. Besides, she said, retailers don't want to be perceived as spying on their customers, so they'll be careful how they use the technology.

Still, the parallels with "Minority Report" weren't lost on one audience member, who referenced the movie in a spiel protesting the technology. "I'm horrified by what you're offering," he said.

-- Alana Semuels

Photo: A woman watching a screen equipped with a TruMedia device will see ads targeted at women. Credit: TruMedia