Where
colours
meet.
One mixture gives us light. Another takes it away. The difference is everything.
↓Explore the experimentAddition. Subtraction. Revelation.
A screen emits light. A coloured material absorbs some wavelengths and returns or transmits others. These are different physical processes, so the same mixing intuition cannot serve both.
Here, RGB lights combine on black; ideal cyan, magenta and yellow filters overlap on white. Try two channels first, then all three. The intersections tell the story.
Make light. Take light away.
Switch between emitted light and ideal filters. Toggle the three channels and inspect their intersections.
Three lights overlap to make white.
How this model works +
Pure RGB circles use screen compositing on black. Ideal CMY filters use multiply compositing on white. With these binary primary values, the intersections illustrate addition and subtraction. This is not a spectral simulation of paint: real pigments also scatter light and have material-specific absorption. Cyan plus yellow here gives green; actual paint mixtures depend on the paints.
Ask what the colour is made of.
A luminous display and a painted surface are different instruments. Understand the medium before choosing the mixture.
Follow the
colour further.
The ideas behind this volume.