Bill’s back! I am pleased beyond measure to present the first video in Engineer Guy Series #4, in which Bill Hammack and his Engineer Guy production team at the University of Illinois unravel the key technology of digital photography: the charge-coupled device. Most of you will probably have a sense of the CCD as a grid of very many, very tiny semiconductor sensors, each of which corresponds to a single pixel in a raster digital photograph. That’s essentially correct. But my intuition, at least, of the more subtle engineering aspects—How does the camera read information off the grid? How does it detect color?—turned out to be dead wrong on both counts. Watch the video, now, and you too may be delightfully surprised, and in any case delighted. Bill’s work is always a pleasure to behold, even if you already know this stuff. Or think you do. [Thanks, Bill!]