Technology takes on the rioters

Face-recognition software, along with more conventional means, is being used to identify suspects.

By PAISLEY DODDS and RAPHAEL, G . SATTER

August 12, 2011 at 3:24AM

LONDON - Facial-recognition technology being considered for London's 2012 Olympic Games is getting a workout to deal with Britain's riots, a senior police official said Thursday, with officers feeding photos of suspects through Scotland Yard's newly updated face-matching program.

Chief Constable Andy Trotter of the British Transport Police said the sophisticated software was being used to help find those suspected of being involved in the worst unrest London has seen in a generation.

But he cautioned that facial recognition makes up only a small fraction of the police force's efforts, saying tips have mostly come from traditional sources, such as still images captured from closed-circuit cameras, pictures gathered by officers, footage shot by police helicopters or images snapped by members of the public. One department was driving around a large video screen displaying images of suspects.

"There's a mass of evidence out there," Trotter said. "The public are so enraged that people who wouldn't normally come forward are helping us -- especially when they see their neighbors are coming back with brand-new TVs."

A press officer with Scotland Yard -- who spoke anonymously, in line with force policy -- confirmed that facial-recognition technology was at the police's disposal, although he gave few details. He said that generally the technology would be used only to help identify those suspected of serious crimes, such as assault, and that in most cases disseminating photographs to the general public remains a far less expensive and more effective way of finding suspects.

The facial-recognition technology used by police treats the human face like a grid, measuring the distance between a person's nose, eyes, lips and other features. It has recently been upgraded, according to an article published last year in Scotland Yard's bimonthly magazine, the Job.

The March 2010 article said that the new program has been shown to work far better than older versions of the technology, with one expert quoted as saying that it had shown promise in identifying people from high-quality, face-on shots taken from surveillance photographs, mobile phones, passports or the Internet.

A law enforcement official said that to use the technology, "you have to have a good picture of a suspect, and it is only useful if you have something to match it against. In other words, the suspect already has to have a previous criminal record."

He spoke on condition of anonymity because he was not authorized to discuss ongoing investigations.

In another effort to identify suspects, police have released two dozen photos and videos to the picture-sharing website Flickr, where they've already gathered more than 400,000 hits. Some of those photographs have also been published by Britain's brash tabloid press.

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PAISLEY DODDS and RAPHAEL, G . SATTER