Pigments manipulate the incoming light and partially reflect it. These reflected components trigger a colour stimulus in the human eye, which is transformed into a colour by the brain. This manipulation of light is described by physics as the transformation into a colour by physiology. However, we cannot identify how the manipulation really happens. For example, if we mix a red and a yellow pigment to create orange, then this orange may look the same as an orange pigment but the blend's reflectance curve has a typical saddle that lacks the orange pigment. In principle, pigments reflect in the entire ...