Foveon X3 sensor

The Foveon X3 sensor as used in digital cameras has a layered sensor so that at each photosite three colours are detected by the photons entering the sensor at deeper layers. The resulting image would have just one pixel for each 3 photosites (unless the image has been interpolated to increase resolution).

Foveon sensors are not as widespread as Bayer sensors. They are only supplied by one company (Foveon, Inc., Santa Clara, CA, USA) and are currently used in two cameras manufactured by Sigma and will be used in a Polaroid digital camera.