EURASIP Journal on Applied Signal Processing 
Volume 2003 (2003), Issue 9, Pages 914-921
doi:10.1155/S1110865703303099

The PLSI Method of Stabilizing Two-Dimensional Nonsymmetric Half-Plane Recursive Digital Filters

N. Gangatharan and P. S. Reddy

 Faculty of Engineering, Multimedia University, Jalan Multimedia, Cyberjaya 63100, Selangor, Malaysia
Received 19 April 2002; Revised 19 February 2003

Abstract

Two-dimensional (2D) recursive digital filters find applications in image processing as in medical X-ray processing. Nonsymmetric half-plane (NSHP) filters have definitely positive magnitude characteristics as opposed to quarter-plane (QP) filters. In this paper, we provide methods for stabilizing the given 2D NSHP polynomial by the planar least squares inverse (PLSI) method. We have proved in this paper that if the given 2D unstable NSHP polynomial and its PLSI are of the same degree, the PLSI polynomial is always stable, irrespective of whether the coefficients of the given polynomial have relationship among its coefficients or not. Examples are given for 2D first-order and second-order cases to prove our results. The generalization is done for the Nth order polynomial.