FOUR PIGMENTS. ONE COLOUR THAT ISN’T THERE.
A grey cloak. A room full of amber light.
What colour does your eye make of it?
An experiment in colour context.
No blue pigment required.
Look first. Then take the surroundings away.
Aim the pinhole at the broad middle fold, below the face. Compare it with the full room.
A small palette. A surprisingly wide world.
THE FOUR-COLOUR PALETTE
Start with black and white. Keep the mix quiet, then lay it against the warm ground.
Parts are relative, like scoops of paint. This illustrative ivory black has a cool cast; its mixes are not exactly neutral like the study cloak.
Drag to paint, or use the patch button. Switch to grey to inspect the very same marks.
THREE SMALL EXERCISES
WHAT’S HAPPENING UNDERNEATH?
Colour appearance depends on nearby colours and on the light we infer. Warm surrounds can make an unchanged grey feel cooler. This is a simultaneous contrast demonstration, related to the broader problem of colour constancy studied by Retinex theory. No Retinex filter is running here.
Read about Retinex ↗The mixer combines absorption and scattering across 31 wavelength samples using an opaque-layer Kubelka–Munk model. It does not average RGB colours. Its pigment spectra are illustrative estimates, not measured tube paints: treat the recipes as digital experiments, not studio predictions.
Read about the model ↗Black, white, red and yellow ochre are often called the Zorn palette. That does not mean Anders Zorn never used blue. Technical analysis has identified cobalt blue and chrome green in his work. These are original digital studies, not reproductions of his paintings.
The conservation research ↗Don’t see blue? That’s a valid observation. The effect varies with the picture, your vision, display settings and room light. Compare the surroundings; there is no perception test to pass.