The single-pixel digital camera

The rule of thumb for signal processing is that the captured signal must be sampled at a rate at least twice its highest usable frequency in order to be reproduced without error. (For example, a CD stores music sampled at roughly 44KHz, whereas the highest frequency most people can hear is around 22KHz.) However, with digital cameras, the signal is often compressed soon after being captured, trading image accuracy in favour of smaller file sizes and some error (consider JPEG image compression, for example).
Clearly, this is wasteful of valuable sensing resources. Over the past year, a new theory of "compressed sensing" has begun to emerge, in which the signal is sampled and compressed simultaneously at a greatly reduced rate.

Using this theory, researchers have created a camera capable of capturing high(ish) resolution images using a single photo diode. Their approach is based on a digital still or video camera that directly acquires random projections of the image and later reconstructs it into an image.

The camera uses a digital micromirror array to help separate a linear signal into almost random binary patterns, which can be converted into a usable image.