3.2 Nonparametric skin distribution modelling
The key idea of the non-parametric skin modelling methods is to estimate
skin color distribution from the training data without deriving
an explicit model of the skin color. The result of these methods
sometimes is referred to as construction of Skin Probability Map
(SPM) [Brand and Mason 2000], [Gomez 2000] - assigning a probability
value to each point of a discretized colorspace.