Dr. Rhys Lewis from IBM's Hursley Labs came in to talk about image processing. In plain graphics applications, you are concerned with taking information stored in a database (or wherever) and producing a picture. Digital image processing addresses the reverse situation - you take a picture with a camera and extract information from it.

Given a photograph of an old English town, it is possible to determine where the edges are in the picture (buildings, walls, sidewalks and so forth). The algorithm he used for this was to take the picture and put it out of focus. Then, subtract the original picture from the fuzzy one. The result is a photograph that is mostly lines where edges used to appear in the picture.

Various techniques for image enhancement are used in medicine. He showed us a slide of an x-ray taken of a patient with a collapsed lung. After telling us what to look for, he conceded that he couldn't see a collapsed lung in the x-ray. After applying a series of transforms on the digitized x-ray, a more visible line appeared where the lung separated from the chest cavity. Now ANYBODY could see a collapsed lung in the x-ray. Fascinating stuff.