I began by adding shades of red, purple and green( using the airbrush on color mode) and then decided to stipple the skin, keeping it lighter and less erratic than I did with the man.
I use a relatively heavy foot and stipple deeply at around 4200 strokes per minute.
It's claimed that a round tool cannot produce as dark a stipple as a faceted one, as it's more difficult for light to reflect from a tiny cavity which has flat walls.
The paper researches algorithms about halftone, stipple simulation, paint simulation and pen-and-ink simulation which are in the area of Non-Photorealistic Rending.
