The Foveon X3 Direct Image Sensor featured in Sigma digital cameras uses three layers of photodiodes to gather the entire red, green and blue color information of light, forming the world’s one and only full color capture system. Downstream processing of color and luminance information is minimized to preserve the most delicate nuances of texture in this pioneering format.
Taking advantage of the characteristics of silicon, this image sensor absorbs different light wavelengths at different levels, using a structure similar to color film. Full RGB light information is captured at each pixel location. This ideal system lets Sigma cameras faithfully record the actual color image coming through the lens.
Beginning with our first digital camera in 2002, all Sigma cameras have used this same sensor format. The name “Foveon” is taken from the fovea centralis, the central portion of the human retina that has the most acute vision, reflecting our pursuit of the ideal visual experience.
The Sigma DP1 Merrill’s Foveon X3 Direct Image Sensor utilizes the characteristics of silicon to absorb shorter wavelengths (blue) near its surface and longer wavelengths (green, then red) at deeper levels. This three-layer full color capture system can record the full color information at each pixel location, enabling richly detailed, vividly colorful images, without the compromises of color interpolation required by conventional sensors.
The image sensor in most conventional digital cameras uses an RGB color filter array (CFA) over a monochrome sensor. Each photosite receives just one of the RGB colors, so downstream interpolation processing is required to create a full-color image.
False colors (moiré) appear in this conventional system because of interference between details in the subject. An optical low-pass filter is therefore required to clean up the image, but at the expense of apparent sharpness.
In contrast, Sigma’s sensor technology needs no color filter, so it doesn't sacrifice fine detail. The resulting high-definition image captures the full information focused by the lens on the sensor.
People are amazed at the almost uncanny atmospheric detail preserved by the high resolution of Sigma cameras. The secret is simply that our unique system neither adds anything to the image nor takes anything away.