Application of Order Statistics Filters to Cardiac Boundary Determination in Ultrasound Images

Abstract

Nonlinear order statistics filters are useful for impulsive noise removal and edge preservation. Speckle is a source of impulsive noise in ultrasound images. Edge preservation is important for determination of cardiac boundaries in echocardiographic images. Additionally, order statistics filters also suppress Gaussian noise which is often present in echocardiograms. Pitas and Venetsanopoulos reviewed order statistics filters² and described a class of edge detectors¹ based on nonlinear means and medians. They showed that a linear combination of these filters, resulting in a ranked-order filter (that operates with a selected range of ordered maximum and minimum gray level values), will further improve the noise removal capabilities.