How can I use wavelet thresholding with nondecimated 2D decomposition of an MR image ?

Question

Hareni Jagadeesan 2013-12-28

0
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https://ww2.mathworks.cn/matlabcentral/answers/110902-how-can-i-use-wavelet-thresholding-with-nondecimated-2d-decomposition-of-an-mr-image

回答： Anjoo Patel 2023-5-31

I am applying Bilateral Filter to the approximations and I want to soft threshold the details from level 3 ..How can I implement wthcoef2 for the non decimated wavelet decomposition structure ?

data = load('mri'); % MRI dataset (magnitude image) distributed with MATLAB
image_num=15;
im = double(data.D(:,:,1,image_num)); % image_num max=27
s=5;
im_r = rician(im, s); % Add Rician noise (make Rician distributed)
% Compute ranges
min_o = round(min(im(:)));  
max_o = round(max(im(:)));
min_r = round(min(im_r(:))); 
max_r = round(max(im_r(:)));
s = 0.05*max_o; % Percentage of NOISE LEVEL
im_R=rician(im,s);
w='haar';
NBCOL = size(data.map,1);
n=3;
%Multilevel Undecimated Discrete 2D Wavelet Transform
WT  = ndwt2(im_R,n,w);    
A = cell(1,n);
D = cell(1,n);
for k = 1:n
    A{k} = indwt2(WT,'a',k);   % Approximations 
    D{k} = indwt2(WT,'d',k);   % Details
end
DH=[];
for k=1:n
    D1=D{k};
    D1=D1(:);
    DH=[DH D1];
end
delta=median(abs(DH))/0.6745;
thr=delta * sqrt(2*log(n));
NC = wthcoef2('t',WT.dec,WT.sizes,1,thr,'s');