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The Digital Rainbow
The Bayer pattern, on the left end, is the most used arrangement of red, blue, and green pixels for
capturing images on a microchip. But it’s not the only way to arrange your pixels. In fact, red, blue, and
green aren’t the only colors you’ll find lurking in a color filter array (CFA). Second is a Bayer pattern
substituting the subtractive primary colors, as found in Kodak DCS620x. Third is a red/green/blue array to
which Sony’s DCS F828 adds an emerald filter. The fourth pattern sports cyan, magenta, yellow, and green
pixels, used by some video cameras to create a compromise between maximum light sensitivity and high
color quality. On the right end, an unfiltered photoreceptor is nestled in an array of photocells filtered
yellow, cyan, and green, a scheme that Hitachi created and that JVC uses in some video cameras.The Foveon X3
image sensors found in
some Sigma and Polaroid
cameras attack the deficiencies of
Bayer matrix sensors by eliminating the
matrix. They use a natural property of silicon
that makes it absorb different colors of light at
different depths in the silicon. Blue light is absorbed
near the surface, green farther down, and red deeper still.3
In the Foveon photodetectors, each of the three levels converts the energy from the three colors of light into three
separate electrical signals that are used to represent a single color pixel. In contrast with the Bayer matrix photo-
detectors below, no light is lost to filters absorbing two of the three colors and less surface area is lost to the layout
of the separate receptors for each color.4
CHAPTER 7 HOW LIGHT BECOMES DATA