The Bayer arrangement of color filters, an image sensor.
In most consumer digital cameras today, a Bayer filter mosaic is used in conjunction with an optical filter anti-aliasing to reduce the aliasing due to reduced sampling of the various primary-color images. A demosaicing algorithm is used to interpolate color information to create a full array of image data of RGB. Cameras that use a single-shot 3CCD approach beam-splitter, three-filter multi-shot approach, or Foveon X3 sensor uses no anti-aliasing filters, nor demosaicing.
The firmware on the camera, or software in a raw converter program such as Adobe Camera Raw, interprets the raw sensor information to obtain a complete picture of color, because the RGB color model requires three intensity values for each pixel: one each for red, green, and blue (other color models, when used, also require three or more values per pixel). A single sensor element can not simultaneously record these three intensities, and so a color filter array (CFA) should be used to selectively filter a particular color for each pixel.
The Bayer filter pattern is a repeating pattern of 2 × 2 mosaic of light filters, with green ones at opposite corners and red and blue in the other two positions. The high proportion of green takes advantage of human visual system characteristics, which determines brightness mostly green and is far more sensitive to brightness than to hue or saturation. A standard 4-color filter is sometimes used, often involving two different shades of green. This provides a potentially more accurate color, but requires a slightly more complicated process of interpolation.
The values of color intensity not captured for each pixel can be interpolated (or be guessed) values of adjacent pixels which represent the color being calculated