Subtractive color mixer

Digital colour tools almost always mix light: red and blue become magenta because channels add in RGB. Painters and designers who think in pigment expect something else—red and blue should muddy toward purple-brown, yellow and blue should pull toward green, and equal mixes of complementary paints should dull rather than brighten. This subtractive color mixer takes two hex colours and a ratio, converts them into RYB pigment coordinates, blends those coordinates as if you mixed wet paint, and returns the resulting sRGB hex and channels. Use it when you need intuitive pigment blends for illustration, craft tutorials, educational demos of subtractive colour theory, or design systems that should not pretend paint behaves like screen light.

How subtractive RYB mixing differs from RGB light blending

Additive mixing models how coloured lights combine on a display: red light plus green light yields yellow, and more light generally means a brighter result. Subtractive mixing models pigments and dyes: each pigment absorbs some wavelengths, and combining pigments absorbs more, so mixes tend toward darker, duller results rather than pure secondary light. This capability implements a classic paint-inspired path.

First each input hex is parsed into sRGB channel values from zero to two hundred fifty-five. Those channels are mapped into red-yellow-blue pigment space with a redistribution that extracts yellow from red-plus-green and folds residual green into yellow and blue, following the paint-inspired conversion popularized in visualization research. Compared with a pure RGB lerp, red mixed with blue at fifty percent is no longer a clean mid-magenta; the pigment path yields a more brownish or purple-mud result that matches how learners describe mixing paint.

Yellow and cyan-ish blues pull toward greens. Complementary pairs dull. That is the intentional product difference from the existing RGB color mixer in the catalog, which remains the right tool when you want screen-light interpolation.

Where a subtractive pigment mixer earns its place

Art education sites and STEAM lesson builders need a live demo that answers “what happens if I mix this red with that blue like paint?” without shipping a full colour-management stack. Craft and DIY generators that suggest yarn, resin tint, or watercolour combinations should not use light-add math if the user is thinking in tubes of pigment.

Keep requests tiny, store the returned hex for reproducible design tokens, and treat invalid hex as client errors rather than retries. If you need linear RGB blends for UI theming, use the additive color mixer instead; if you need paint intuition, this is the dedicated path.