It's interesting to go back to the release of the SD9, before Sigma and\nFoveon attempted to re-define what a pixel actually is!\n\nSigma Press Release\n-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\nThe breakthrough Sigma SD9 camera with Foveon(R) technology has the world's\nfirst image-sensor that features three layers of photodetectors. The layers\nare embedded in silicon to take advantage of the fact that red, green and\nblue light penetrate silicon to different depths allowing full-color to be\nmeasured at every pixel. The layers are positioned to take advantage of the\nfact that silicon absorbs different colors of light at different depths, so\none layer records red, another layer records green and the other layer\nrecords blue. This means that for every pixel on a Foveon(R) X3TM image\nsensor, there's actually a stack of three photodetectors, forming the first\nand only full-color capture system.\n\nFoveon Press Release\n-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\nThe Foveon X3 image sensor in the Sigma SD9 contains over 10.2 million color\nphotodetectors, which are organized in 3 layers within the sensor to form\n3.54 million full-color pixels. By dedicating three color photodetectors for\neach pixel, the SD9 produces images that are sharper, have better color\ndetail and are more immune to color artifacts than currently available six\nmegapixel digital SLR cameras. The Foveon X3 image sensor is the world's\nfirst full-color image sensor that captures red, green and blue light at\nevery pixel in a single exposure. The Foveon X3 technology breakthrough is\naccomplished by embedding three photodetectors in silicon at each pixel.\n\n-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\n\nWow, look at that!\n\nSigma says: "...for every pixel on a Foveon(R) X3TM image sensor, there's\nactually a stack of three photodetectors...\nFoveon says: "The Foveon X3 technology breakthrough is accomplished by\nembedding three photodetectors in silicon at each pixel."\n\nI don't know when the marketing people went crazy.