What is the colorimetric purity of a color when no white light is added to it?

Colorimetric purity refers to the degree to which a color is free from white light, essentially measuring its saturation. When no white light is mixed with a color, it is considered to be fully saturated and is perceived in its most vivid form. This results in a colorimetric purity value of 1, indicating that the color is pure and completely unadulterated by any additive white light.

In contrast, if any white light were added to the color, the purity would decrease. A purity value of 0 would indicate complete desaturation, leading to a shade of gray resulting from the mixture of the color with white light. Values like 0.5 or 1.5 do not represent standard measures for colorimetric purity, as purity is typically expressed within a range of 0 to 1. In summary, the optimal situation for colorimetric purity arises when a defined color stands alone, yielding the highest level of purity represented by the value of 1.