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A. Asano, K. Itoh, and Y. Ichioka,
RONDO: Rank-Order based Nonlinear Differential Operator
Pattern Recognition, 25, 9, 1043-1059 (1992).


A class of new differential filter that is a generalized version of the weighted median filter is proposed. The weighted median filter is a generalization of the median filter that has weight coefficients. In this paper, we propose an extended version of the weighted median filter that has negative weight coefficients. We call it the rank-order based nonlinear differential operator(RONDO). We show that RONDO acts as an effective differential operator. It detects edges in images degraded by impulsive noise effectively. It also has clear selectivity of edge orientation.


Median filters, Weighted Median Filter, Image differentiation, Edge detection, Threshold decomposition, Statistical analysis