Method and apparatus for noise reduction

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36472401, 364825, 358340, 348607, 333166, H04B 1500

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active

054900948

ABSTRACT:
A noisy input signal x is filtered with a restoration filter of median type to generate a filtered input signal y. The sum of the absolute differences between filtered and unfiltered signal is calculated for each position of a sliding window within the input signal representing a local estimate of the noise, and is combined with a global measure of the input signal noise to compute two coefficients a and b which are respectively applied to the unfiltered and filtered signal to generate the output signal z=a*x+b*y which is both globally and locally adapted to the structure of displayed images. Advantageously different kinds of filters operate in parallel, whereby the kind of filter elected is locally adapted to the picture activity.

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