rasred2004
Joined: 23 Jan 2007
Posts: 3
Helped: 1
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 12 Feb 2007 18:22 Re: wiener filter and wavelet |
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| omidi_sbu wrote: |
| How can I use a wiener filter with wavelet packet transform to have the minimum distortion? |
the wiener filter is an option of the wavelet packet transfrom as shown in the code of the wavelet packet transform
function w=wpk2d(x,lp,hp,basis)
%WPK2D 2-D Discrete Wavelet Packet Transform
%
% Y = WPK2D(X,H,G,BASIS) calculates the Wavelet Packet
% Transform of vector X. The second argument H is the
% lowpass filter and the third argument G the highpass filter.
% The BASIS argument specifies the desired subband decomposition.
% It can be obtained using a basis selection algorithm.
%
% Run the script 'BASIS' for help on the basis format and 'FORMAT2D'
% for help on the output format.
%
% Uvi_Wave is free software; you can redistribute it and/or modify it
% under the terms of the GNU General Public License as published by the
% Free Software Foundation; either version 2, or (at your option) any
% later version.
%
% Uvi_Wave is distributed in the hope that it will be useful, but WITHOUT
% ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
% FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
% for more details.
%
if (~basis) % trivial case
w=x;
return
end
basis=basis-1;
wx=wt2d(x,lp,hp,1); % perform one analysis level
% into the analysis tree
if all(basis==0) % four ending nodes achieved
w=wx;
return
end
[ly,lx]=size(wx); % separate approximation and details
a=wx(1:ly/2,1:lx/2); % at the analysis output
v=wx(ly/2+1:ly,1:lx/2);
h=wx(1:ly/2,lx/2+1:lx);
d=wx(ly/2+1:ly,lx/2+1:lx);
% Approximation case
tope=1; % finds the point where the
suma=2^(-basis(1)*2); % basis vector must be divided
i=1; % in order to call the recursion
while (suma<tope)
i=i+1;
suma=suma+2^(-basis(i)*2);
end
if all(basis(1:i)~=0) % a level with an ending node
wa=wpk2d(a,lp,hp,basis(1:i)); % but the other node continues
else wa=a;
end
% Vertical residue case
basis=basis(i+1:length(basis));
suma=2^(-basis(1)*2);
i=1;
while (suma<tope)
i=i+1;
suma=suma+2^(-basis(i)*2);
end
if all(basis(1:i)~=0)
wv=wpk2d(v,lp,hp,basis(1:i));
else wv=v;
end
% Horizontal residue case
basis=basis(i+1:length(basis));
suma=2^(-basis(1)*2);
i=1;
while (suma<tope)
i=i+1;
suma=suma+2^(-basis(i)*2);
end
if all(basis(1:i)~=0)
wh=wpk2d(h,lp,hp,basis(1:i));
else wh=h;
end
% Diagonal residue case
basis=basis(i+1:length(basis));
if all(basis~=0)
wd=wpk2d(d,lp,hp,basis);
else wd=d;
end
% arrangement of the band sizes
% it is necessary when any of the original sizes is not a power of 2
c1=size(wa,2)-size(wv,2); % difference in the number of columns
if c1<0 % between the approx. and vertical residue band
wa=[zeros(size(wa,1),-c1) wa]; % we add blank columns to the smallest,
elseif c1>0 % in order to match band sizes
wv=[zeros(size(wv,1),c1) wv];
end
c2=size(wh,2)-size(wd,2); % idem, between horizontal and diagonal residues
if c2<0
wh=[zeros(size(wh,1),-c2) wh];
elseif c2>0
wd=[zeros(size(wd,1),c2) wd];
end
f1=size(wa,1)-size(wh,1); % difference in the number of rows
if f1<0 % between the approx. and horizontal residue band
wa=[zeros(-f1,size(wa,2)) ; wa]; % we add blank rows to the smallest,
elseif f1>0 % in order to match band sizes
wh=[zeros(f1,size(wh,2)) ; wh];
end
f2=size(wv,1)-size(wd,1); % idem, between vertical and diagonal residues
if f2<0
wv=[zeros(-f2,size(wv,2)) ; wv];
elseif f2>0
wd=[zeros(f2,size(wd,2)) ; wd];
end
w=[ [wa,wh] ; [wv,wd] ]; % fit the four bands
Added after 6 minutes:
| omidi_sbu wrote: |
| How can I use a wiener filter with wavelet packet transform to have the minimum distortion? |
if you need any help and you do not know how to use the matlab code just send me a e.mail
rasred2004(at)yahoo.com
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