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Crave privacy? New tech knocks out digital cameras

With this photo-blocking system, celebrities may never again have to punch out the paparazzi. Photos: The Georgia Tech "photo neutralizer"

Researchers at the Georgia Institute of Technology have come up with an inexpensive way to prevent digital cameras and digital video cameras from capturing that secret shot.

The technology they've devised detects the presence of a digital camera up to 33 feet away and can then shoot a targeted beam of light at the lens, according to Shwetak Patel, a grad student at the university and one of the lead researchers on the project.

click to view photos of prototype

That means that someone trying for a surreptitious snapshot of, say, a product prototype or an amorous couple gets something altogether less useful--a blurry picture (or a video) of what looks like a flashlight beam, seen head on. (A video of how the system works can be viewed here.)

The group has developed a lab prototype--which consists of a digital projector with a modified video camera mounted on top--but will soon design a device that could be manufactured and sold commercially. The group, which presented a paper on its work at Ubicomp (The Seventh International Conference on Ubiquitous Computing) in Tokyo last week, is also in contact with large consumer electronics manufacturers.

Though photo-foiling gadgets are one possibility, the technology might also eventually be incorporated into digital projectors and other devices as a feature.

The Georgia Tech researchers aren't alone in their pursuit. Tech giant Hewlett-Packard, for one, has applied for a patent on technology that could remotely cause blurry pictures in digital cameras, but it requires putting additional circuitry inside the camera. HP and others are also working on projection technology meant to stymie video piracy.

The technology is a stab at ameliorating the privacy problems that have arisen with the advent, quick ubiquity and tiny dimensions of digital cameras. Nearly 85 percent of cell phones in Japan come with built-in digital cameras, and the figure for North America and Western Europe is supposed to rise to 80 percent by the end of next year, according to market researcher Gartner.

"It certainly is a concern, and it has been a concern since cameras have gotten really small," said Steve Baker, an analyst at NPD Group. "It is a lab trick that has some real-world application."

Companies commonly confiscate digital cameras temporarily from visitors coming to their labs or confidential meetings. "But you can't confiscate a phone. Someone might be expecting an important call," Patel said.

Many companies also maintain strict no-photography policies in quasi public places. Someone trying to take pictures inside a Wal-Mart or an electronics boutique will immediately draw a warning, or expulsion. Conferences also have similar rules. Patel himself got in trouble trying to take a picture of a "No Photography" sign to illustrate where the invention could be used.

"If it is a big exhibit hall, it is impossible to confiscate all of the cameras," said Patel.

How it works
The Georgia Tech system essentially exploits the "retroreflective" property of digital camera lenses. When light strikes a retroreflective surface, a portion of the light bounces back to the original source. While eyeglasses, bottles, watches and other glass surfaces are retroreflective, a coating on virtually all digital camera lenses puts cameras in a class of their own.

"The film atop lenses (is) highly reflective," said Patel. "A lot of people probably have known this but they haven't thought about leveraging it."

In this system, a device bathes the region in front of it with infrared light. When an intense retroreflection indicates the presence of a digital camera lens, the device then fires a localized beam of light directly at that point. Thus, the picture gets washed out.

The neutralizing light continues until the camera lens can no longer be detected, which prevents video cameras from capturing clear footage.

For added security, the system emits light beams in a pattern that prevents cameras from compensating for the light. (In the lab prototype, the video camera, with its built-in infrared beam, serves as the camera detector, while the projector is the neutralizer.)

The technology can detect and block multiple cameras and works on cameras with either CCD or CMOS imagers, which are used in the vast majority of digital cameras.

The neutralizing light is also highly focused to minimize distractions. "We only light up pixels where the reflection is coming from," Patel said.

More work lies ahead for the researchers. The current implementation works indoors and only up to certain distances--it's effective at a range of up to 10 meters and covers a 45-degree area. Cameras close to the detector and at a sharp angle can fall into an undetectable dead zone. Fast shutter speeds might also present some challenges, as do filters, though it turns out that the camera detector can spot lenses cloaked with infrared filters.

While the prototype relies on a digital projector for the neutralizing light source, the group believes it can also use a laser pointer and two mirrors to foil photographers.

"That will make it a lot cheaper to do," Patel said.

The prototype is also rather indiscriminate--it knocks out whatever it believes to be a camera. Some companies have released antiphotography tools, but those tools work only if the camera or cell phone has a Bluetooth chip--and then only if the gadgets are preprogrammed to shut down when the chip receives a "no photographs" message.

So the broad nature of the Georgia Tech system is a good thing, Patel said. "It doesn't require cooperation of the camera."