Also called three primary colors; they are red, yellow and blue.
Color difference
The light has a different refractive index due to its different wavelengths, resulting in a hue deviation called chromatism. Also refers to the difference between a known color and a color standard.
Toning chart
Based on the red, yellow, and blue colors, two of the primary colors are mixed to obtain a color; adding another primary color to the intermediate color results in a complex color, so that a variety of hue can be obtained. In order to achieve the desired effect, the tone is adjusted. The coloring of the chemin dye is to adjust the color and avoid darkness or lightness.