Fig. 8.

As a 50- $\mu$ m-thick vascular plexus with 5% blood content is moved further from the skin surface, the skin color changes from slightly orange to slightly pink. Above the plexus, the dermis is relatively blood free with only thin capillaries circulating red blood cells. Blue light is partially reflected from this superficial layer before it can reach the blood in the plexus and be absorbed, hence blue reflectance increases. This simple model only approximates true skin structure to illustrate the effect.