Foveon Image Sensor Technology
The Foveon X3® direct image sensor* featured in the Sigma DP1 can capture all primary RGB colours at each and every pixel, insuring the capture of full and complete colour. Using three silicon-embedded layers of pixel sensors, stacked to take advantage of silicon's ability to absorb red, green, and blue light at different respective depths, it efficiently reproduces colour more accurately, and offers sharper resolution, pixel for pixel, than any conventional image sensor. * Foveon X3 is the registered trademark of Foveon.

Until now, all other image sensors have featured a just single layer of pixels and each pixel captures only one colour of light, which has been filtered through a single colour filter. Since mosaic-based conventional image sensors capture only one-third of the colour, complicated algorithms are required to interpolate the colour they miss. Interpolation leads to colour errors, colour artifacts and a loss of image detail. Low pass filters must then be used to reduce colour artifacts. The use of low pass filters adversely affects sharpness and resolution of the final image captured.

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Pixel Counting Definitions
Prior to the existence of the Foveon X3 direct image sensor, there has been a 1:1 relationship between the number of pixels (photodetectors) and the number of pixel locations for a traditional CCD and CMOS image sensor. Given this relationship, the generic term “pixel” has been commonly used to reference both the pixel (photodetector) and the pixel location. Foveon direct image sensors are a new type of image sensor that incorporates three pixels (photodetectors) at every pixel location on the image sensor. The definition of a pixel as indicated below is consistent with standard industry conventions as applied to CCD image sensors, CMOS image sensors, and the Foveon X3 direct image sensor.

Pixel
A pixel on the image sensor of a digital camera is a light absorbing element (photodetector) that converts light (photons) into electrons. A pixel is also referred to as a pixel sensor when there is a need to distinguish the pixel from its location.

Pixel Location
A pixel location is the X,Y coordinate on the two-dimensional grid of an image sensor at which the pixel is located. A Foveon X3 direct image sensor consists of three layers of pixels. Each pixel detects 1 color sample.