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# error 'index exceeds matrix dimensions'

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SIBI SIVA on 17 Oct 2016
Closed: MATLAB Answer Bot on 20 Aug 2021
figure
for i=1:11
y(:,:,k3)=idwt2(llf(:,:,i),lhf(:,:,i),hlf(:,:,i),hhf(:,:,i),'haar');
s=mat2gray(y(:,:,k3));
subplot(4,4,i)
imshow(s);
k3=k3+1;
end
figure
i1=1;
j1=1;
a1(i1:i1+63, j1:j1+63)=mat2gray(cell2mat(P(1)));
a1(i1:i1+63, 65:65+63)=mat2gray(cell2mat(P(2)));
a1(i1:i1+63, 129:129+63)=mat2gray(cell2mat(P(3)));
a1(i1:i1+63, 193:193+63)=mat2gray(cell2mat(P(4)));
a1(65:65+63, j1:j1+63)=mat2gray(cell2mat(P(5)));
a1(65:65+63, 65:65+63)=mat2gray(s(:,:,1));
a1(65:65+63, 129:129+63)=mat2gray(s(:,:,2));
a1(65:65+63, 193:193+63)=mat2gray(s(:,:,3));
a1(129:129+63, j1:j1+63)=mat2gray(s(:,:,4));
a1(129:129+63, 65:65+63)=mat2gray(s(:,:,5));
a1(129:129+63, 129:129+63)=mat2gray(s(:,:,6));
a1(129:129+63, 193:193+63)=mat2gray(s(:,:,7));
a1(193:193+63, j1:j1+63)=mat2gray(s(:,:,8));
a1(193:193+63, 65:65+63)=mat2gray(s(:,:,9));
a1(193:193+63, 129:129+63)=mat2gray(s(:,:,10));
a1(193:193+63, 193:193+63)=mat2gray(s(:,:,11));
imshow(a1);
i use this part of code to reassemble the watermarked blocks of an image. but it shows the error 'Index exceeds matrix dimensions.
Error in aftrR2 (line 185)
a1(65:65+63, 129:129+63)=mat2gray(s(:,:,2)); ' .
can anyone help me solve the error.thanks in advance.
KSSV on 17 Oct 2016
Check the dimensions of every matrix you are using and see the loop's which you are using to call the matrices.

Jan on 17 Oct 2016
Edited: Jan on 17 Oct 2016
The message means, that the variable "s" does not have the size 2 in the third dimension. Check this:
dbstop if error
Then runm your code again until Matlab stops at the error. Now check the size of the variables unsed in the failing line.
I guess the problem is here:
s = mat2gray(y(:,:,k3));
After the loop "s" is the last gray image, which is a 2D matrix. Then mat2gray(s(:,:,2)) accesses a not existing 3rd dimension and tries to convert it to gray levels again.