Abstract

A new two-parameter family of median type filter (MF), termed the vector median filter (VMF).that outputs at each pass a set of numbers, is described. Here, the order of the sort depends on the sign of the first derivative of the signal in the data window. If the sign is positive (negative), the sort is in increasing (decreasing) order. The VMF preserves edges while it filters out impulses. Because of its two design parameters, the VMF offers a wider range of filtering possibilities. For example, one can adaptively adjust the subwindow according to the results of the derivative test. While computationally the VMF is slightly more complex than the MF, it is significantly faster in numerical implementation. Computer simulations, on both signals and images, indicate that in many cases the outputs of the VMF and the MF are identical. Both statistical and deterministic properties of the VMF are also examined.

© 1985 Optical Society of America