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September 19th, 2005 - A group of Gerogia Tech researchers have developed a device that they claim could block digital cameras and cameraphones from taking photos. The device, which uses an Infra-Red light source to blind the camera, is being touted as a way to protect the privacy of products being shown at a trade show before launch.
The camera blocker (which the researchers built as part of a research project to create a "Capture Resistant Environment") detects the camera by using the Infra-Red (IR) light source built into a Sony camcorder fitted with an IR filter: camera lenses reflect this light, creating a distinct hot spot in the camcorder image rather like the bright eyes that you see on animals when shooting in night vision mode. Image processing software running on a connected PC then detects this hot spot and triggers a series of IR LEDs mounted around the camera lens that turn on and off quickly. These IR lights overwhelm the sensor (in the same way that a bright light would) and lead to overexposed pictures that are virtually indiscernible. The rapidly changing lighting (as the LEDs turn on and off) also prevents the sensor from adapting to the changing lighting conditions, and the IR LEDs are invisible to the human eye, so the people watching the demo aren’t affected or aware of the blocking.
However, the device is far from foolproof: as the inventors themselves concede, the device can be blocked by using an IR filter (which blocks the reflection it uses to detect the camera) or by someone taking a picture from outside the field of view of the camera or camcorder that detects the camera.
According to press reports of a presentation that the team made, they are planning to expand the system using a laser and mirrors to more accurately target the offending camera.
There is a 256Kb PDF file that describes how the device works and how they built it. There are also videos and images on their Web site that show the effect the device has on a camcorder or digital camera.
(Images taken from the GA Tech Web site at http://www.cc.gatech.edu/~summetj/cre/index.html