GRBG

GRBG is a Bayer color filter array (CFA) pattern used in digital image sensors. It defines the arrangement of color filters in a repeating 2x2 tile: top-left is green, top-right is red, bottom-left is blue, bottom-right is green.

This two-green-per-tile design provides higher sampling density for luminance and supports the human eye's sensitivity to green. Each photosite (pixel) records the intensity of its filter color, while the other two colors are estimated during demosaicing, the process by which a full-color image is reconstructed from the incomplete color data captured by the sensor.

GRBG is one of several Bayer CFA variants; others include RGGB, GBRG, and BGGR. The choice of arrangement can influence the direction of interpolation artifacts and the complexity of demosaicing algorithms, but all rely on the same underlying principle of interpolating missing color channels from neighboring samples.

Historically, the Bayer pattern was introduced by Bryce Bayer at Kodak in 1976 and has become the dominant CFA in consumer and professional digital cameras. In practice, GRBG patterns are implemented in silicon as part of the mosaic atop the photodiode array, and software demosaicers convert the mosaic into standard RGB images.

Because many cameras and image pipelines allow selecting or detecting the CFA pattern, software may assume standard GRBG, RGGB, etc., with calibration to ensure accurate color reproduction. See also Bayer filter, demosaicing, RGGB, BGGR.