Cameras that use a beam-splitter single-shot 3CCD approach, three-filter multi-shot approach, Color co-site sampling or Foveon X3 sensor do not use anti-aliasing filters, nor demosaicing.

The Foveon X3 sensor is a CMOS

The development of the Foveon X3 technology is the subject of the 2005 book The Silicon Eye by George Gilder.

Color absorption in silicon and the Foveon X3 sensor.

On the right, a Foveon X3 layered sensor stack in the silicon wafer for each output pixel is shown depicting the colors it detects at each absorption level.

Because the depth in the silicon wafer of each of the three layer Foveon X3 sensors is less than five micrometres, it has negligible effect on focusing or chromatic aberration.

The first digital camera to use a Foveon X3 sensor was the Sigma SD9, a digital SLR launched in 2002.

Foveon X3 sensors were also used in the Hanvision HVDUO-5M and HVDUO-10M, a pair of digital cameras aimed at the scientific and industrial markets.

The operation of the Foveon X3 sensor is quite different from that of the Bayer filter image sensor more commonly used in digital cameras.

Because demosaicing is not required for the Foveon X3 sensor to produce a full-color image, the color artifacts (" colored jaggies ") associated with that process are not seen.

Another difference is that more of the photons entering the camera will be detected by the Foveon X3 photosensor than is possible with a mosaic sensor.

Although the Foveon X3 has greater light gathering ability, the individual layers do not respond as sharply to the respective colours.

This filter is largely unnecessary with the Foveon X3 sensor and is not used.

The earliest camera with a Foveon X3 sensor, the Sigma SD9, showed visible luminance moiré patterns, but not color moiré.

Aliasing from the Foveon X3 sensor is " far less bothersome because it's monochrome " according to Norman Koren.

Therefore, in theory, it is possible for a Foveon X3 sensor with the same number of photodiodes as a Bayer sensor and no separate anti-aliasing filter to attain a higher spatial resolution than that Bayer sensor.

Independent tests indicate that the " 10. 2 MP " array of the Foveon X3 sensor ( in the Sigma SD10 ) has a resolution similar to a 5 MP

With the introduction of the Sigma SD14, the 14 MP ( 4. 7 MP red + 4. 7 MP green + 4. 7 MP blue ) Foveon X3 sensor resolution is being compared favorably by reviewers to that of 10 MP Bayer sensors.

Another article judges the Foveon X3 sensor as roughly equivalent to a 9 MP Bayer sensor.

The Foveon X3 sensor, as used in the Sigma SD10 camera, has been characterized by two independent reviewers as noisier than the sensors in some other DSLRs using the Bayer sensor at higher ISO film speed equivalents,

With regards to the Sigma SD14 which uses a more recent Foveon X3 sensor, one reviewer judged its noise levels as ranging from " very low " at ISO 100 to " Moderate " at ISO 1600 when using the camera's Raw image format.

* Sample gallery of Sigma SD14 with Foveon X3 sensor

* Foveon X3 technology page

* DPReview Foveon X3 prototype preview

image sensor for digital cameras, designed by Foveon, Inc. ( now part of Sigma Corporation ) and manufactured by National Semiconductor

A visual comparison between a 14 MP Foveon sensor and a 12. 3 MP Bayer sensor shows Foveon has crisper details.

Like its predecessor, the SD10 uses a sensor with the unique Foveon X3 sensor technology.

Although the image file is smaller than images from competing 10 megapixel cameras it is made from the same number of measured data values because the Foveon sensor detects full color data ( three values ) at each photosite ; the actual resolution contained in its 3. 4 MP images is about the same as a conventional Bayer / CFA sensor of 7 – 9 MP.

The 14-MP Foveon chip produces 4. 7 MP native-size RGB files ; 14-MP Bayer filter cameras produce a 14 MP native file size by interpolation ( demosaicing ).

Sigma's SD14 site has galleries of full-resolution images showing the color produced by the current state of Foveon technology.

Direct visual comparison of images from 12. 7-MP Bayer sensors and 14. 1 MP Foveon sensors show Bayer images ahead on fine monochrome detail, such as the lines between bricks on a distant building, but the Foveon images are ahead on color resolution.

It was Sigma's first digital camera, and was the first production camera to use the unique Foveon X3 image sensor, which reads full color at each pixel site.

Common values for field of view crop in DSLRs include 1. 3x for some Canon ( APS-H ) sensors, 1. 5x for Sony APS-C sensors used by Nikon, Pentax and Konica Minolta and for Fujifilm sensors, 1. 6 ( APS-C ) for most Canon sensors, ~ 1. 7x for Sigma's Foveon sensors and 2x for Kodak and Panasonic 4 / 3 " sensors currently used by Olympus and Panasonic.

Although DNG supports more sensor configurations than TIFF / EP, ( for example, cameras from Fujifilm using Super CCD sensors ), it still doesn't support all sensor types as raw images, especially those using the Foveon X3 sensor or similar, hence especially Sigma cameras.

Other sensor sizes found in DSLRs include the Four Thirds System sensor at 26 % of full frame, APS-H sensors ( used, for example, in the Canon EOS-1D Mark III ) at around 61 % of full frame, and the Foveon X3 sensor at 33 % of full frame.

Foveon was initially known for their high-end digital portrait camera systems built around a color-separation beam-splitter prism assembly.

Sigma and Foveon count each red, green, and blue sensor as a pixel, and state the camera has 10. 2 million pixels ; similarly, companies selling Bayer sensor cameras also count each single-color sensor element as a pixel.

Faggin also oversaw the successful acquisition of Foveon by the Japanese Sigma Corporation in November 2008.

The current exceptions are the Micro Four Thirds system by Olympus and Panasonic ; the Sigma DP1, which uses a Foveon X3 sensor ; the Leica X1 ; the Canon PowerShot G1 X, which uses a 1. 5 " ( 18. 7 x 14mm ) sensor that is slightly larger than the Four Thirds standard and is 30 % of a fullframe sensor ; and two models from Sony, the RX100 with a 1 "- type ( 13. 2 x 8. 8mm ) sensor with about half the area of Four Thirds and the full-frame Sony RX1.

On 11 November 2008, when Federico Faggin was the CEO, all shares of Foveon stock were acquired by Sigma Corporation.

During his tenure as president and CEO of Foveon, from 2003 to 2008, Faggin revitalized the company and provided a new technological and business direction resulting in image sensors superior in all critical parameters to the best sensors of the competition, while using approximately half the chip size of competing devices.

* " Executive Profile " from Foveon. com

According to Sigma Corporation, " there has been some controversy in how to specify the number of pixels in Foveon sensors.