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### 2D inverse stationary wavelet packet

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```Hello dear Friends,
I am inspired from the 1D swpt posted on the forum to build the 2D swpt (swpt2).
I think that the foward transform (swpt2) works well but reconstruction gives bad results. Can you help me on the inverse transformation and if possible suggest me an idea on the best basis selection in function of entropy criterion.
Thx

Here are the highlights
1. swpt2.m
function coeffs=swpt2(x,n,type)

siz=size(x); [lo,hi]=wfilters(type,'d'); lo=lo(:)'; hi=hi(:)';
old_modeDWT=dwtmode('status','nodisp');
modeDWT='per'; dwtmode(modeDWT,'nodisp');
coeffs = cell(n,2^(2*n));
k=1;m=1;
lf=length(lo);first=[lf+1,lf+1];x=wextend('2D',modeDWT,x,[lf/2,lf/2]);
[coeffs{k,4*m-3},coeffs{k,4*m-2},coeffs{k,4*m-1},coeffs{k,4*m}] = decomposeLOC(x);
% upsample filters.
lo(2,length(lo))=0; lo=lo(:)'; hi(2,length(hi))=0; hi=hi(:)';
for k = 2:n
for m = 1:2^(2*(k-1))
lf =length(lo); first=[lf+1,lf+1];
x =wextend('2D',modeDWT,coeffs{k-1,m},[lf/2,lf/2]);
[coeffs{k,4*m-3},coeffs{k,4*m-2},coeffs{k,4*m-1},coeffs{k,4*m}] =    decomposeLOC(x);
end
% upsample filters.
lo(2,length(lo))=0; lo=lo(:)';hi(2,length(hi))=0;hi=hi(:)';
end
% Restore DWT_Mode.
dwtmode(old_modeDWT,'nodisp');
%---------------------------------------------------------------%
function [ch,cv,cd,ca] = decomposeLOC(x)
y=conv2(double(x),lo);z=(conv2(y',lo))';ca=keepLOC(z,size2D);
z=(conv2(y',hi))'; ch=keepLOC(z,size2D); y=conv2(double(x),hi);
z=(conv2(y',lo))'; cv=keepLOC(z,size2D);z=(conv2(y',hi))';cd=keepLOC(z,size2D);
end
function y = keepLOC(z,siz)
sz=size(z); siz(siz>sz)=sz(siz>sz); last=first+siz-1;
y=z(first(1):last(1),first(2):last(2),:);
end
end

2. iswpt2.m (???)
function y=iswpt2(swpc2,n,type)

[lo,hi]=wfilters(type,'r'); lo=lo(:)'; hi=hi(:)';
for k=n:-1:1
step=4^(k-1);subband=4^k;last=step;
y=swpc2{k,1};[rx,cx]=size(y);
for r=1:4:subband;
for first=1:last
iRow=first:step:rx;lR=length(iRow);iCol=first:step:cx;lC=length(iCol);
sR=iRow(1:2:lR);sC=iCol(1:2:lC);
ca=swpc2{k,r+3};ch=swpc2{k,r+2};cv=swpc2{k,r+1};cd=swpc2{k,r};
x1=idwt2LOC(ca(sR,sC),ch(sR,sC),cv(sR,sC),cd(sR,sC),lo,hi,[lR lC],[0,0]);
sR=iRow(2:2:lR);sC=iCol(2:2:lC);
x2=idwt2LOC(ca(sR,sC),ch(sR,sC),cv(sR,sC),cd(sR,sC),lo,hi,[lR lC],[-1,-1]);
y(iRow,iCol) = 0.5*(x1+x2);
if k>1
swpc2{k-1,(r+3)/4}= y;
end
end
end
end
%---------------------------------------------------------------%
function y=idwt2LOC(a,h,v,d,lo_R,hi_R,sy,shift)
y=upconvLOC(a,lo_R,lo_R,sy)+ upconvLOC(h,hi_R,lo_R,sy)+ ...
upconvLOC(v,lo_R,hi_R,sy)+ upconvLOC(d,hi_R,hi_R,sy);
if shift(1)==-1 , y=y([end,1:end-1],:); end
if shift(2)==-1 , y=y(:,[end,1:end-1]); end
end
function y=upconvLOC(x,f1,f2,s)
lf=length(f1);
y=wconv2('col',y,f1);y=wconv2('row',y,f2);
y=wkeep2(y,s,[lf lf]);
end
end
```
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7/14/2012 1:45:56 AM