CCD/CMOS sensor grid with red-green-blue pixel mosaic — standard architecture in all digital cameras. Debayering reconstructs full RGB image.
Bayer Mosaic Pattern Sensor
The sensor in your digital camera is not, as you might intuitively think, paved with millions of complete RGB pixels. Instead, a microscopic grid of individual color filters—red, green, and blue—is arranged on the CCD or CMOS in a pattern developed by Bryce Bayer at Kodak in 1976. Each pixel captures only one color. The intelligence lies in the fact that there are twice as many green filters as red or blue ones, because the human eye perceives green brightness information more strongly than red or blue. This asymmetry is why the sensor works at all.
On set, you won't notice this at first—the camera provides you with a complete raw image. This happens through debayering, an interpolation process that takes place in the camera's firmware or later in color grading. The algorithm reconstructs the missing color channels for each pixel by using neighboring pixels. Good debayering algorithms work adaptively and avoid color fringing. Poor ones create artifacts, especially at sharp contrast edges. That's why the sensor architecture of a RED or ARRI matters—different manufacturers optimize the pattern and interpolation differently.
In practice, this mainly affects you in extreme situations: if you have very fine details in the original image—net structures, thin lines, high-frequency patterns—debayering can lead to moiré or color shift. That's why most sensors have optical low-pass filters in front of them, which slightly attenuate high-frequency information. This is a conscious compromise: fewer artifacts, but minimal loss of sharpness. RAW footage gives you the unfiltered sensor output and control over the debayering method in the edit—one reason why many DoPs shoot RAW when production allows. You then decide for yourself how aggressive or conservative the color reconstruction should be.
Understanding this architecture also helps you with troubleshooting. A green cast in the shadows? Often a debayering artifact. Unexpected color separation at critical transitions? The algorithm is struggling with local contrasts. An experienced colorist can counteract this through targeted debayering setup or grade optimization—but only if you know that the information was originally processed this way.