Illumination-robust Pattern Matching Using Distorted Color Histograms

It is argued that global illumination should be modeled separately from other incidents that change the appearance of objects. The effects of intensity variations of the global illumination are discussed and constraints deduced that restrict the shape of a function that maps the histogram of a template to the histogram of an image location. This approach is illustrated for simple pattern matching and for a combination with a PCA (\emph{Eigenface}) model of the grey-level appearance.