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03 Oct 2005
A video camcorder equipped with infrared LEDs helps prevent unauthorized photography with cell phones.
An optical security system that can prevent camera phone users from snapping pictures in restricted areas has been developed by researchers in the US. Its inventors from Georgia Institute of Technology unveiled the scheme at the Ubiquitous Computing conference (UbiComp 2005) in Tokyo last month.
The computer-controlled prototype consists of an off-the-shelf projector and a video camera retro-fitted with a ring of infrared (IR) LEDs and an IR filter. The LEDs bathe the area with IR light and the video camera searches for a telltale reflection from the CMOS or CCD chip of a cell phone camera.
When a camera is spotted, the projector flashes a beam of intense light that overwhelms the camera’s white-balance algorithms, making its image appear totally washed-out and rendering it impossible to take a picture or video. The projector continues flashing until the camera is undetectable. By mapping the location of every detected camera, the projector can neutralize multiple cameras simultaneously.
To avoid being activated by objects such as spectacles, watches and metallic surfaces that also reflect IR light, the system uses computer algorithms that pick out the unique signature reflection generated by CMOS and CCD imaging chips.
Currently, the system only works indoors and has a range of up to 10m, covering a 45 degree field of view. However, the Georgia Tech team says that a commercial version could make use of inexpensive microcontrollers and laser diodes, to make it more affordable and enhance its performance. The team says that several art galleries and exhibition halls have already expressed interest in the idea.
“The most important aspect of our method is that it does not require the cooperation of the person who owns the camera,” said Jay Summet, one of the Georgia Tech researchers. Previous attempts at blocking camera phones from taking images relied on sending “No Photography” messages over Bluetooth and WiFi to all phones in the area. But their success was conditional to the user being cooperative or the camera being preprogrammed to shut-off upon receipt of such a message.
A video of the project, can be found here.
Author
A.L. Narayan is an electronics engineer and a writer for On Target Media a Singapore-based technology content provider.
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