I've been reading this article from EPFL, about a new kind of imaging sensor. Each pixel, or photodetector, measures the light by producing a binary value of either 0 or 1. So, each pixel is, loosely speaking, a photon counter. The advantage of this sensor is that it has the potential to be really fast (high frame rate). Once such binary data is collected, a grayscale image can be obtained from it by applying image processing techniques. This is similar to what the eye does when it sees the spatial dithering in newspaper halftones.
