Undefined function 'wprec2' for input arguments of type 'double'.

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Balkar Singh
Balkar Singh on 22 Aug 2021
Commented: Balkar Singh on 24 Aug 2021
I applied wpdec2 (Wavelet Packet transform) on a color image with size 512 * 512. It generates a subtree then I applied wpcoef to get it coefficients. On these coefficients I created blocks and apply DCT and inverse of DCT and blocks. Then i applied wprec2 after reverse process of block. Then i got a error as given below:
Undefined function 'wprec2' for input arguments of type 'double'.
Please help to troubleshoot this problem.

Accepted Answer

dpb
dpb on 22 Aug 2021
Without the actual code sequence we can't tell but the doc for wprec2 says it expects a wavelet packet tree object.
If you've munged on the output of wpdec2 to produce some output array of double, then you've broken the contract between the two of the forward/reverse transform.
All wprec2 promises is that it will reproduce X from the output of wdec2 operating on X
  1 Comment
Balkar Singh
Balkar Singh on 24 Aug 2021
clear all;
img = imread('Image9.png');
T = wpdec2(img,6,'db5');
Tree_cfs = read(T,'allcfs');
X = wpcoef(T);
blksize=[8,8];
blk1 = our_blkproc(X,blksize);
dct_data = zeros(8,8,size(blk1,3));
for i=1:size(blk1,3)
dct_data(:,:,i) = dct2(blk1(:,:,i));
end
dct_data_inv = zeros(8,8,size(blk1,3));
for i=1:size(blk1,3)
dct_data_inv(:,:,i) = idct2(dct_data(:,:,i));
end
final_data = our_blkproc_rev(dct_data_inv);
final_data = reshape(final_data,1,[]);
x1 = wprec2(final_data);
I tried this code

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