Some representation properties of stack filters

Stack filters, a class of nonlinear filters which are based on positive Boolean functions as the window operators, are considered. The representations of these window operations are presented via the structures of on-set and off-set of the positive Boolean functions, which can be expressed as a Boolean expression containing no complements of the input variables. A fast algorithm for finding the representation of stack filters is designed. This algorithm can be easily extended to find the representation of morphological filters mentioned by P. Maragos (1989)