Foveon sensor
From The Glossary of Digital Photography
A new type of digital image sensor. Most image sensors have pixels that are sensitive to only one color. They are grouped together in an array known as a Bayer array. The camera's processor combines these pixels to produce a full-color image. In a Foveon sensor, all of the pixels are sensitive to all three RGB (red, green, and blue) colors because there are three photo sensors, set in layers, at each location. No demosaicing is necessary for Foveon sensors because they do not use a Bayer array. Thus a processing step and a potential source of image degrading are eliminated. So far, Foveon sensors have not become popular with the major camera manufacturers. See also demosaicing
