Overview
Louis Ducos du Hauron (1837–1920) published the theory of subtractive three-colour photography in 1869: record three separation negatives through red, green and blue filters, then print them in the complementary dyes — cyan, magenta and yellow — superimposed. Technicolor, Kodachrome, colour negative film and every inkjet printer are implementations of what he described.
What You Need
- Lived: 1837–1920, France
- Anchor year: 1869 — subtractive three-colour photography
- Strand: overlooked — the theory is his, the industries are not
Steps
The problem as it stood
Photographic emulsions record brightness, not colour. Reproducing colour requires separating the scene into components, recording each, and recombining them — and in 1869 nobody had established which components, or how to recombine them on paper.
What he actually did
Ducos du Hauron published a complete scheme, and made prints to demonstrate it. Photograph the subject three times through red, green and blue filters; make a positive from each in the complementary dye; superimpose them. He also anticipated additive screen processes and the anaglyph.
How it worked
Additive mixing adds coloured lights and starts from black; subtractive mixing removes wavelengths from white light using dyes and starts from white. Paper and film are illuminated by white light, so they must be subtractive — cyan absorbs red, magenta absorbs green, yellow absorbs blue. That distinction is the reason the CMY set is the right one.
What it made possible
All chemical colour photography and cinematography. Technicolor's three-strip process is his scheme mechanised; Kodachrome is his scheme with the dyes formed in a single tripack; colour negative film and every CMYK printing process follow the same logic.
What happened to him
He worked largely alone, patented widely and profited little, and died in poverty in 1920 — more than a decade before Technicolor made his principle commercially enormous.
Where the credit landed
Ducos du Hauron is credited in histories of photography and almost never in histories of film or television, which begin the colour story at Technicolor. Charles Cros published a closely related scheme at essentially the same moment, and the two are usually cited together — Cros appears elsewhere in this corpus for the paleophone. Being sixty years early and dying before the payoff is a recurring shape in this history.
Pro Tips
- Additive starts from black and adds light; subtractive starts from white and removes it.
- Film and paper are viewed by reflected or transmitted white light, so they must be subtractive.
- Technicolor and Kodachrome are both implementations of an 1869 scheme.
Knowledge Base
What You'll Learn
Colour reproduction is a solved problem from 1869 onward; everything after is engineering.
Why three
Human colour vision has three cone types, so any colour a person can see can be matched by an appropriate mixture of three suitably chosen primaries. That is a fact about the eye rather than about light — a spectrophotometer would need far more channels. Every colour system in this corpus, from Technicolor to PAL to a phone screen, exploits the same three-channel limitation of human vision.
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 the difference between additive and subtractive colour?
A: Additive mixing combines coloured lights, starting from darkness — used by screens, with red, green and blue. Subtractive mixing uses dyes to remove wavelengths from white light, starting from white — used by film and print, with cyan, magenta and yellow.
Q: Did Ducos du Hauron make colour photographs?
A: Yes. He produced demonstration prints using his three-negative subtractive method from around 1869, decades before commercial colour photography existed.