Some statistical properties of alpha-trimmed mean and standard type M filters

The statistical properties of two classes of filters generalizing the median filter are considered. The two classes are the alpha-trimmed mean (α-TM) filter and the standard type M(STM) filter, both of which are special cases of the L filter. Results are developed to quantify the white-noise suppression and edge-preservation characteristics of the filters by considering their output sequence error statistics. It is shown that the α-TM and STM filters perform better than the running mean and median filters in white noise suppression, while they can be designed to be comparable to the median filter in edge preservation in the presence of noise