Multilevel median filters: properties and efficacy

The authors discuss detail-preserving, ranked-order based filtering algorithms. These filters fall, roughly, into one of two categories: adaptive and non-adaptive. The main advantage of non-adaptive filters is that neither a-priori information of the image is required, nor does one need to compute local statistics inside the filters window. The authors consider non-adaptive, structure preserving filters only. In particular, they analyze the class of multilevel median filters, and compare their efficiency with that of other detail-preserving filters including multilevel FIR-median hybrid and morphological filters. For completeness, they also include results for the square median filter