?? normnoise.m
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function [y,coef] = NormNoise(x,qmf)
% NormNoise -- Estimates noise level, Normalize signal to noise level 1
% Usage
% [y,coef] = NormNoise(x,qmf)
% Inputs
% x 1-d signal
% qmf quadrature mirror filter
% Outputs
% y 1-d signal, scaled so wavelet coefficients
% at finest level have median absolute deviation 1.
% coef estimation of 1/sigma
%
% Description
% This is required pre-processing to use any of the DeNoising
% tools on naturally-occurring data.
%
% See Also
% WaveShrink, CPDeNoise,WPDeNoise
%
u = DownDyadHi(x,qmf);
s = median(abs(u));
if s ~= 0
y = .6745 .* x ./s;
coef = .6745 /s;
else
y = x;
coef = 1;
end
%
% Copyright (c) 1993-5. Jonathan Buckheit, David Donoho and Iain Johnstone
%
% Modified by Maureen Clerc and Jerome Kalifa, 1997
% clerc@cmapx.polytechnique.fr, kalifa@cmapx.polytechnique.fr
%
%
% 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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