Single Pixel Camera

Using some new mathematics and a silicon chip covered with hundreds of thousands of mirrors the size of a single bacterium, engineers at Rice University have come up with a more efficient design. Unlike a one mega pixel camera that captures one million points of light for every frame, Rice's camera creates an image by capturing just one point of light, or pixel, several thousands of times in rapid succession. New mathematics comes into play in assembling the high-resolution image – equal in quality to the one-mega pixel image – from the thousands of single-pixel snapshots.

"White noise is the key," said Richard Baraniuk, the Victor E. Cameron Professor of Electrical and Computer Engineering. "Thanks to some deep new mathematics developed just a couple of years ago, we are able to get a useful, coherent image out of the randomly scattered measurements."

Baraniuk's collaborator Kevin Kelly, assistant professor of electrical and computer engineering, built a working prototype camera using a digital micro mirror device, or DMD, and a single photodiode, which turns light into electrical signals. Today's typical retail digital camera has millions of photodiodes, or mega pixels, on a single chip.

In a regular camera, a lens focuses light, for a brief instant, onto a piece of film or a photodiode array called a CCD. But in the single-pixel camera, the image from the lens is shined onto the DMD and bounced from there though a second lens that focuses the light reflected by the DMD onto a single photodiode. The mirrors on the DMD are shuffled at random for each new sample. Each time the mirrors shift, a new pixel value is recorded by the photodiode. In effect, the lens and DMD do what the microchip in the digital camera usually does; they compress the data from the larger picture into a more compact form.; Source: Rice University