HELLO MY Die-Hard Fanbase of radical RGB Photophiles! This is taken from a very excellent and fair review of the Sigma DP1, the camera that drove me insane.
ReAd ThE wHoLe ReViEw ViA clickyclicks
Foveon X3 sensor background
Terminology
- Photodetector - A physical device used to capture a single color value (for a Bayer camera there is one of these per pixel location, the X3 sensor has three per pixel location)
- Pixel location - A location on the final image which contains full RGB color information
What's so good about the Foveon X3 sensor?
In the example below we are simplifying things by using a 130 x 130 sensor, thus a total of 16,900 pixel locations in the output image. Obviously the same rules apply no matter many pixel locations the final image has.
Traditional "Mosaic" sensors
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Digital cameras have for years used what is essentially a monochromatic (b&w) image sensor with individual color filters over each photodetector (known as the Bayer pattern and normally in a GRGB pattern). This means that each photodetector can only detect one of either red, green or blue light. Note that the green channel has twice the number of photodetectors as red or blue (this is because the majority of luminance information is carried in the green channel). A demosaic algorithm then combines the color of neighboring pixels to reproduce the scene color at that pixel location.
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| Red 4,225 photodetectors | Green 8,450 photodetectors | Blue 4,225 photodetectors | Output 16,900 pixel locations |
Foveon's X3 sensor
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