It is not always as easy as the example in Figure 5 to locate a face, because the background may contain skin colors, too.
A variety of distributions of energy quanta of photons can be perceived as the same color. This means that many points
in the color space representing the different physical distributions of photon energy quanta can be mapped onto a single
point in the color space. In other words, the mapping between the physical spectrum and the color space can be many-to-one. It is impossible to locate faces simply from the result of color matching.