Image credit & licenceOverview
Bryce Edward Bayer (1929–2012) devised the Bayer filter at Kodak in 1976: a mosaic of red, green and blue filters over a monochrome sensor, with twice as many green cells as red or blue. Essentially every colour digital camera sensor uses it or a derivative.
What You Need
- Lived: 1929–2012, United States
- Anchor year: 1976 — the Bayer filter
- Strand: overlooked — in every digital camera
Steps
The problem as it stood
An image sensor measures light intensity and knows nothing about colour. Getting three colour values per location seemed to need three sensors and a beam splitter — the Technicolor solution, expensive and bulky — or three sequential exposures, useless for moving subjects.
What he actually did
Bayer put a mosaic of colour filters directly over the sensor, one colour per photosite, in a repeating pattern with twice as many green as red or blue. The missing two values at each site are reconstructed from neighbours.
How it worked
Human vision resolves luminance detail far better than colour detail, and luminance perception is dominated by the green part of the spectrum. Weighting the mosaic toward green therefore samples most finely exactly where the eye is most sensitive to detail. The reconstruction — demosaicing — exploits the same asymmetry.
What it made possible
Single-sensor colour cameras: every consumer digital camera, phone, camcorder and most professional cinema cameras. It is why raw files exist as a distinct format, since raw data is the undemosaiced mosaic.
What happened to him
He spent his career at Kodak in imaging science and died in 2012. The pattern carries his name, which is unusually good attribution for this corpus, though very few of the billions of people using it daily know it.
Where the credit landed
Bayer's name survives on the pattern, so attribution held better here than in most of this wave. The idea also rests on the same perceptual asymmetry — luminance detail matters more than chrominance detail — that underlies colour subsampling in video and the chroma handling in JPEG and MPEG. It recurs throughout the corpus because it is a fact about eyes, not about engineering.
Pro Tips
- Twice as many green cells because luminance perception is dominated by green.
- Raw files are the undemosaiced mosaic — that is what makes them raw.
- The same luminance-over-chrominance asymmetry drives chroma subsampling in video.
Knowledge Base
What You'll Learn
One filter pattern, resting on one fact about human vision.
The same asymmetry, everywhere
Human vision resolves brightness detail far better than colour detail. The Bayer pattern samples green most finely for that reason. Video chroma subsampling — 4:2:2 or 4:2:0 — discards colour resolution for the same reason and is why chroma keying against a heavily subsampled source produces ragged edges. JPEG subsamples chroma too. One property of the eye, exploited independently at three different points in the chain.
Where This Fits
This guide covers one specific part of the history of media technology. The wider picture — how each link in the chain from capture through transmission to display was actually built, who built it, and why the credit so often landed somewhere else — is in A History of Broadcast Technology: The Chain From Capture to Screen, which frames the discipline as a whole and links out to the detailed guides underneath it, including this one. If you are starting from scratch rather than solving a specific problem, read that first and come back here.
FAQ
Q: What is a Bayer filter?
A: A mosaic of red, green and blue filters over a monochrome image sensor, with twice as many green cells as red or blue. Each photosite measures one colour, and the other two are reconstructed from neighbours by demosaicing.
Q: Why twice as many green?
A: Because human luminance perception is dominated by the green part of the spectrum, and the eye resolves brightness detail far better than colour detail. Sampling green most finely puts the resolution where it is most visible.