Lights, Camera -- Jamming

A prototype device seeks out cameras and blocks them from taking pictures and video.

As the bootlegging of first-run movies increases, with the availability of inexpensive digital cameras, there should be a way to thwart them, says Gregory Abowd, associate professor in the College of Computing at Georgia Tech. To do this, he and his team have developed a device that can detect the presence of a digital camera or camcorder -- and keep it from capturing usable images.

Two researchers at Georgia Tech with a prototype device that can detect digital cameras and camcorders and prevent them from taking useful images. (Courtesy of Gary Meek.)

Researchers have been trying to develop effective ways to jam a camera for years, says Edward Delp, professor of electrical and computer engineering at Purdue University. A number of companies, including Philips, Thomson, and Apogen Technologies, as well as a handful of universities, have been working on projects and prototypes. The Georgia Tech approach, which combines methods of detecting a camera and the means to automatically prevent it from taking pictures is "a nice technology," says Delp, that achieves these two goals in one device, while also using infrared light to spot cameras, in contrast to some other combination systems.

To locate a camera, the researchers exploited a component of many digital cameras and camcorders: the charge-coupled device (CCD) that converts light collected by a camera's lens into an image stored in its memory. Because of its shape, a CCD is retro-reflective, meaning it reflects incoming light back out at the same angle. Taking advantage of this, the Georgia Tech device shines infrared LED light, which is invisible to the human eye, at a distance of about 20 feet, then collects video of these reflections with a camcorder, Abowd explains. Then the video of the reflections is transferred to a computer, where it's sent through image-processing algorithms that pick out infrared light bouncing back. And to decrease the chances of false positives -- infrared light reflecting off other objects, such as eyeglasses and earrings -- the researchers added image-processing algorithms that account for the specific shape of the CCD reflections and those of other objects.

In the second step, to block the camera from taking pictures, the device uses a projector that emits a narrow beam of white light directly at a CCD. The beam saturates the CCD with varying intensities of light, Abowd says, forcing the camera's electronics to constantly adjust, and ultimately producing large white splotches that cover about one-third of the recorded scene. The result: a low-quality, if not worthless, recording or photograph.