What Comprises The Degree Of Purity Of A Hue?

What Comprises The Degree Of Purity Of A Hue? Saturation: The degree of purity of a hue. Intensity: The brightness or dullness of a hue. One may lower the intensity by adding white or black. What determines hue brightness purity? When discussing spectral “light primaries” (RGB), a pure hue equivalent to full saturation is determined