Application of directional statistics in vector direction estimation

Vector direction estimation can be very important in applications like hue color component filtering or motion direction estimation from noisy motion vector fields. Vector representation and manipulation in polar coordinates greatly facilitates the accomplishment of the previous task. Based on angular estimators of location, the authors introduce a number of “circular” filters, i.e. filters for angular input data. These filters include circular mean, median and a-trimmed mean filters. Emphasis is given to a circular median filter for which the approximate output pdf as well as other interesting properties are derived. The effectiveness of angular estimators of location in noise filtering is studied in simulations involving color images. Simulation results clearly indicate that circular filters can be used effectively to remove noise when the estimation of color hue is of primary importance