Question

What are the factors that influence highlight and shadow colours for skin tones? Shepherd Grimley, Switzerland

Answer

Mark replies

The key for painting realistic skin tones is to be aware of the lighting conditions around your character. The original skin colour only appears in the areas unaffected by direct or reflected light. Yet even these areas are affected by light. This reddish or orange-coloured fine glow is called sub-surface scattering, because the light is scattered around in the tissues and illuminates the skin from the inside.

In this example, I’m painting a character for my Dune-inspired series and I want to create a portrait without showing the iconic desert in the background. I imagine the character standing on the sand, but in front of the rocks near his village. Such an environment results in an almost classical lighting set-up with three main light sources: key, fill and rim light.

My first key light source is the sun with its slightly yellowish colour. The second is rim light – the warm, reflected light from the sand. The fill is the desaturated bluegrey colour of the sky. My approach is to break up a character into surfaces facing the different light sources. In this case all the surfaces facing the upper right are lit by the sun, and the surfaces facing downwards or in the opposite direction are affected by the light bouncing up from the sand.

All the planes facing upward are lit by the sky (reflecting back its colour). But we can only see this colour in the shadows, because the light of the sun is much stronger on the lit surfaces. The same thing goes with the colour of the sandstone rocks – this colour also appears only in the shaded surfaces.

Bear in mind that even your shadows are affected by light. Furthermore, the actual colour of the different surfaces are influenced by their surroundings.