Improvements in or relating to filters

Abstract

Described herein is method for applying noise reduction to multi-dimensional input data by applying a multi-dimensional approximation function to each point in the input data whilst maintaining definition for each discontinuity (620) present in the input data. A control lattice including a plurality of control points (630) is superposed on the input data such that, for each data point, a number of control points surround the data point (640). For each control point (630), a value which is a function of neighbouring data points is computed, and from, at least values of the neighbouring control points, determining an approximation function, which when applied to the input data provides filtered output data. Weighting is applied to at least control point associated with a data point in the vicinity of a discontinuity to maintain the sharpness of the discontinuity during the noise reduction process.

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