Additive light mixing yields white; subtractive pigment mixing yields gray-black

Newton demonstrated that prismatic colors summed back to white light — additive mixing. Pigments work oppositely: each absorbs (subtracts) certain wavelengths, and mixing pigments combines their absorption, driving toward black. Complementary color pairs illustrate the split: in light, two complementaries sum to white; in pigment, they mix to gray-black. This means the same visual ‘complementary’ relationship behaves differently on screen (additive RGB) versus on canvas (subtractive pigment). For shader / generative visual artists, everything on screen is additive (RGB values add toward white 1,1,1); for print or physical media it is subtractive. Confusion between the two systems causes color prediction errors — a common misconception for artists moving between media.

Examples

GLSL: color = colorA + colorB is additive; two complementaries in GLSL at full intensity give white (1,1,1). Painter mixing cyan + red pigment gets dark muddy gray, not white.

Assessment

Explain why mixing red and green light gives yellow but mixing red and green paint gives dark gray. Predict what happens when three complementary pairs of pigments are all mixed together.