Performance measures for rank order filters

When evaluating the quality of rank order filtered images, quantitative measures like the mean absolute error (MAE) criterion have been used only with caution because they do not always agree with the results of subjective tests. In general, a large part of the error in a median filtered image falls into one of two categories: remaining impulses or edge smearing. It is known that the human eye responds differently to these two components, whereas measures like the MAE do not distinguish between them. The authors have decomposed the error components, and by computing the MAE separately for each, have found a pair of perceptually significant error measures