www.pudn.com > multiwavelet.rar > thresh_decor1D.m

function transfth=thresh_decor1D(transf,maxlevel,thresh,covname,threshtype) 
%transfth=thresh_decor1D(transf,maxlevel,thresh,covname,threshtype) 
% 
%  This subroutine performs scalar thresholding with decorrelation of  
%  1-dimensional wavelet transform. Scaling coefficients stay untouched.  
%  Wavelet coefficients are decorrelated using diagonal blocks of the  
%  covariance matrix of the transform. After that all obtained coefficients  
%  are thresholded and correlated again.                             
% 
%  Input:                                                        
%    threshtype  string of characters, either 'hard' or 'soft'; 
%                  threshtype='hard' invokes hard thresholding, 
%                  threshtype='soft' invokes soft thresholding; 
%                for details see [DJ] 
%    covname     string of characters, name of covariance matrix used for  
%                decorrelation; for possible names and short descriptions see 
%                coef_dcov1D.m      
%    thresh      real, value of the threshold 
%    maxlevel    integer, number of levels of wavelet decomposition in transf, 
%                maxlevel < 7 
%    transf      r by n real array, wavelet transform of a signal; 
%                r is the number of scaling functions, 
%                n must be of the form integer*2^maxlevel, 
%                for structure of transf see [SW] 
% 
%  Output: 
%    transfth    r by n real array, thresholded wavelet transform 
% 
%  Example of Usage: 
%    transfth=thresh_decor1D(transf,5,0.75,'ghmap','hard') 
 
% Author: Vasily Strela 
% COPYRIGHT 1997,98 by Vasily Strela 
 
n0=length(transf(1,:)); 
D=coef_dcov1D(covname); 
r=length(D(:,1)); 
transfth=transf; 
 
 
for i=1:maxlevel, 
  d=D(:,(i-1)*r+1:i*r); 
  dd=inv(sqrtm(d)); 
  transfth(:,n0-(2^i-1)*n0/2^i+1:n0-(2^(i-1)-1)*n0/2^(i-1))=dd*transfth(:,n0-(2^i-1)*n0/2^i+1:n0-(2^(i-1)-1)*n0/2^(i-1)); 
end 
 
transfth=thresh(transfth,maxlevel,thresh,threshtype); 
 
for i=1:maxlevel, 
  d=D(:,(i-1)*r+1:i*r); 
  dd=sqrtm(d); 
  transfth(:,n0-(2^i-1)*n0/2^i+1:n0-(2^(i-1)-1)*n0/2^(i-1))=dd*transfth(:,n0-(2^i-1)*n0/2^i+1:n0-(2^(i-1)-1)*n0/2^(i-1)); 
end