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RYB (Red, Yellow, Blue) 1) is a physical colorspace

With white and black pigments, a larger gamut of color nuances can be created including tints and shades.

Ryb 2)

<MATH> \begin{array}{rrrl} & & yellow & + & blue & = & green \\ & & blue & + & red & = & magenta / purple \\ & & red & + & yellow & = & orange \\ red & + & yellow & + & blue & = & brown \\ \end{array} </MATH>

Wheel

A wheel (star) staring:

Subtractive Color Wheel 3)