Electronic Design

System Blocks Unwanted Video And Photos

Researchers at the Georgia Institute of Technology have completed a prototype device that can block digital-camera functions in a given area. Commercial versions of the technology could be used to stop unwanted use of video or still cameras.

The prototype device uses off-the-shelf equipment—camera-mounted sensors, lighting equipment, a projector, and a computer—to scan for, find, and neutralize digital cameras. The system works by looking for the reflectivity and shape of the image-producing sensors used in digital cameras.

Gregory Abowd, an associate professor leading the project, says the new camera-neutralizing technology shows commercial promise in two principal fields: protecting limited areas against clandestine photography or stopping video copying in larger areas such as theaters.

Abowd said the small-area product could prevent espionage photography in government buildings, industrial settings, or trade shows. Preventing movie copying could be a major application for the camera-blocking technology. Movie theaters are ideal for camera-blocking technology.

A camera’s image sensor (CCD) is “retroreflective,” which means it sends light back directly to its origin rather than scattering it. Retroreflections probably would make it relatively easy to detect and identify video cameras in a darkened theater.

The current prototype uses visible light and two cameras to find CCDs. Commercial systems might use invisible infrared lasers and photo-detecting transistors to scan for contraband cameras. When the system finds a suspicious spot, it would feed information about the reflection’s properties to a computer for a determination to avoid false positives caused by shiny objects.

Once a scanning laser and photodetector locate a video camera, the system would flash a thin beam of visible white light directly at the CCD. This beam, possibly a laser in a commercial version, would overwhelm the target camera with light and render recorded video unusable. Researchers say that energy levels used to neutralize cameras would be low enough to preclude any health risks to the operator.

Still camera neutralization in small areas also shows near-term commercial promise, Abowd said. Despite ambient light levels far higher than the levels in a theater, still cameras at a trade show or a mall should be fairly easy to detect, he said. That’s because image sensors in most cell phones and digital cameras are placed close to the lens, making them easier to spot than the deeper set sensors of video cameras.

The camera-neutralizing technology may never work against single-lens-reflex cameras, which use a folding-mirror viewing system that effectively masks its CCD except when a photo is actually being taken. Moreover, anti-digital techniques don’t work on conventional film cameras because they have no image sensor.

Georgia Institute of Technology
http://gtresearchnews.gatech.edu/

TAGS: Components
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