page_title: Foveon X3 sensor
section_title: Operation
hierarchical_section_title: Foveon X3 sensor / Operation
caption_attribution_description: English: Dicklyon &amp; Anoneditor - self created graphic.
context_page_description: The Foveon X3 sensor was a digital camera image sensor designed by Foveon, Inc., and manufactured by Dongbu Electronics.
  It uses an array of photosites that consist of three vertically stacked photodiodes. Each of the three stacked photodiodes has a different spectral sensitivity, allowing it to respond differently to different wavelengths. The signals from the three photodiodes are then processed as additive color data that are transformed to a standard RGB color space.
  The X3 sensor technology was first deployed in 2002 in the Sigma SD9 DSLR camera, and subsequently in the SD10, SD14, SD15, SD1, the compact Sigma DP2 series from 2012, the Sigma dp2 Quattro series from 2014, and the Sigma SD Quattro series from 2016. The development of the Foveon X3 technology is the subject of the 2005 book The Silicon Eye by George Gilder.
context_section_description: The diagram to the right depicts how the Foveon X3 sensor works. The image on the left shows the absorption of colors for each wavelength as it passes through the silicon wafer. The image on the right shows a layered sensor stack depicting the colors it detects at each absorption level for each output pixel. The sensor colors shown are only examples. In practice, the color attributes of each output pixel using this sensor result from the camera's image processing algorithms, which use a matrix process to construct a single RGB color from all the data sensed by the photodiode stack.
  The depth of the silicon wafer in each of the three sensors is less than five micrometers that creates a negligible effect on focusing or chromatic aberration. However, because the collection depth of the deepest sensor layer (red) is comparable to collection depths in other silicon CMOS and CCD sensors, some diffusion of electrons and loss of sharpness in the longer wavelengths occurs.
caption: Wavelength-dependent absorption in silicon and the Foveon X3 sensor. See text for explanation.
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