Color constancy and dynamic adaptation approaches: Obtaining robust color representations against varied illumination conditions is still a major problem. However, the application of color constancy techniques as a preprocessing step to skin-color modeling proved to improve the performance. The NN-based color constancy techniques are very promising as they do not make any explicit assumptions about the scene content. Dynamic
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adaptation techniques which transform the existing color models so as to adapt to the changing viewing conditions are also available. However, the problem with these approaches is that if we lose track of ground truth, the adaptive model might adapt to non-skin image regions. The problem domain factors such as the characteristics of the data set, the real-time considerations and the skin detection method should lead the choice of one of the illumination adaptation methods.