?? wpdenoise.m
字號:
function [clean,bb,st] = WPDeNoise(x,D,qmf)
% WPDeNoise -- De-Noising in an adaptively chosen WP basis
% Usage
% [clean,bb,st] = WPDeNoise(x,D,qmf)
% Inputs
% x 1-d signal to be de-noised.
% D maximum depth of basis tree
% qmf quadrature mirror filter for frequency splitting
% Outputs
% clean cleaned signal
% bb basis tree naming basis in which de-noising was done
% st stat tree: statistics driving basis search
%
% Description
% 1. Assumes noise level == 1
% 2. Uses Stein Unbiased Estimate of risk to evaluate basis
% 3. Uses Coifman-Wickerhauser Best Basis algorithm to select
% best basis
%
% See Also
% WaveShrink
%
[n,J] = dyadlength(x);
thr = sqrt(2 .* log( n .* J) );
%
% Find Best Basis for De-Noising
%
wp = WPAnalysis(x,D,qmf);
st = CalcStatTree(wp,'SURE',thr);
[bb,vt] = BestBasis(st,D);
%
% Apply thresholding in Best Basis
%
dirtycoef = UnpackBasisCoeff(bb,wp);
cleancoef = HardThresh(dirtycoef,thr);
%
% Transform back to time domain
%
cleanwp = PackBasisCoeff(bb,wp,cleancoef);
clean = WPSynthesis(bb,cleanwp,qmf);
%
% Copyright (c) 1993-5. Jonathan Buckheit, David Donoho and Iain Johnstone
%
%
% Part of WaveLab Version 802
% Built Sunday, October 3, 1999 8:52:27 AM
% This is Copyrighted Material
% For Copying permissions see COPYING.m
% Comments? e-mail wavelab@stat.stanford.edu
%
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