www.pudn.com > multiwavelet.rar > dec2D_pe.m

function transf=dec2D_pe(fp,flt,maxlevel) 
%transf=dec2D_pe(fp,flt,maxlevel) 
% 
%  This function computes discrete multiwavelet transform of a preprocessed  
%  2-dimensional signal. Boundaries are handled by periodic extension. 
%  For description of the algorithm see [SW]. 
% 
%  Input:  
%    maxlevel    integer, number of levels of decomposition 
%    flt         string of characters, name of the filter; 
%                for possible names and short descriptions see coef.m 
%    fp          n by n real array, preprocessed input data; 
%                n must be of the form integer*2^maxlevel; 
%                for details of organization of fp see [SW]. 
%                                                    
%  Output:   
%    transf      n by n real array, multiscaling and multiwavelet coefficients; 
%                for details of organization of transf see [SW]  
% 
%  Example of Usage: 
%   transf=dec2D_pe(fp,'bighm2',3)   
 
% Author: Vasily Strela 
% COPYRIGHT 1997,98 by Vasily Strela 
 
[n1,n2]=size(fp); 
 
[L,H]=coef(flt); 
[nf,ns]=size(L); 
 
transf=fp; 
for lv=1:maxlevel 
  nh=n2/nf; 
  aa=zeros(nf,nh); 
  for l=1:n1 
    for j=1:nf 
      aa(j,:)=transf(l,(j-1)*nh+1:j*nh); 
    end 
    aa=dec1D_pe(aa,flt,1); 
    for j=1:nf 
      transf(l,(j-1)*nh/2+1:j*nh/2)=aa(j,1:nh/2); 
      transf(l,n2/2+(j-1)*nh/2+1:n2/2+j*nh/2)=aa(j,nh/2+1:nh);     
    end 
  end 
  nh=n1/nf; 
  aa=zeros(nf,nh); 
  for l=1:n2 
    for j=1:nf 
      aa(j,:)=transf((j-1)*nh+1:j*nh,l)'; 
    end 
    aa=dec1D_pe(aa,flt,1); 
    for j=1:nf 
      transf((j-1)*nh/2+1:j*nh/2,l)=aa(j,1:nh/2)'; 
      transf(n1/2+(j-1)*nh/2+1:n1/2+j*nh/2,l)=aa(j,nh/2+1:nh)';     
    end 
  end 
  n1=n1/2; 
  n2=n2/2; 
end