RGB vs RYB vs CMY for paint

RGB is an additive model for light

A display starts dark and adds red, green, and blue light. Red plus green light can appear yellow; all three channels at high output can appear white. A HEX code is simply a compact instruction for those three display channels.

Paint does not emit those channels. It sits in incoming light, absorbs some wavelengths, scatters others, and sends the remainder toward the eye. Averaging two HEX codes therefore does not simulate the physical mixture of the corresponding paints.

CMY is a cleaner subtractive abstraction

Cyan, magenta, and yellow are complements of the RGB light primaries. In an ideal subtractive system, cyan removes red, magenta removes green, and yellow removes blue. Printing builds on this logic, usually adding black because real inks and paper do not create an efficient neutral dark.

CMY can be a helpful mental model for transparent colorants, but artist paint is not ideal ink. Particle scattering, opacity, binder, film thickness, and pigment-specific absorption alter the result.

RYB remains practical, but it is not a uniform standard

The red-yellow-blue wheel reflects a long studio tradition and gives intuitive names to orange, green, and violet mixtures. Its weakness is that “red” and “blue” cover broad pigment families. A warm cadmium red and cool magenta behave differently; ultramarine and phthalo blue open different portions of the mixing gamut.

A split-primary RYB palette solves much of that ambiguity by keeping two versions of each primary. It is a workflow choice, not proof that those paints are mathematically pure primaries.

Spectral mixing describes the material more directly

A reflectance spectrum records how much light a sample returns at many wavelengths. A physical mixture model combines wavelength-dependent absorption and scattering rather than only three display values. Mixora uses 36 bands and a Kubelka–Munk model to rank candidate recipes, then converts the predicted reflectance to CIELAB for comparison.

Choose the model for the question

• Use RGB and HEX to identify a digital target consistently.
• Use CIELAB and Delta E to compare perceived digital differences.
• Use RYB language to plan familiar studio hue moves.
• Use CMY ideas to understand subtractive complements and transparent color.
• Use spectral data when you need a more physical mixture prediction.
• Use a dried swatch to decide whether the final material match succeeds.

A practical translation sequence

Capture the target as a controlled digital reference, choose compatible paints, let the calculation find a short candidate recipe, and mix measured parts. Apply the paint on the intended ground, allow it to dry, then correct value, hue, and chroma in that order. The models organize the search; the swatch supplies the evidence.