Wavelet and image processing

Hi there!

Alright, so I've been working on this little piece of code to approximate image using wavelets and there's this error I'm getting:

Subscripted assignment dimension mismatch.

So the code goes this way:

I = imread('lena.png');
J = perform_wavelet_transf(I,j0,+1);
n = size(I,1); 
J1 = zeros(n);
J1(1:n/4,1:n/4) = J(1:m,1:m);
result = perform_wavelet_transf(J1,j0,-1);
imshow(result,[]);

I've been wondering since hours on what could possibly go wrong with this piece and I guess somethings not right with

J1(1:n/4,1:n/4) = J(1:m,1:m);

What do you think?

And yes, Thanks alot!!! for your help in advance :)

[Walter Roberson]

Which line is the error occurring on?

[Ayesha]

The fifth line:

J1(1:n/4,1:n/4) = J(1:m,1:m);

Answer 1

[Walter Roberson]

You have not shown us how you construct "m" so all we can do is hypothesize that you construct it without regard for the actual size of lena.png

[Ayesha]

That's the part I'm experimenting since wavelets deals with coarse details and hence j0 is an integer.

j0=128;
M = 2^(-j0);
m=sqrt(M);

[Walter Roberson]

sqrt(2^-128) is 2^-64, which is a number less than 1. 1:m would then be the empty range, so J(1:m,1:m) would be empty. You are trying to store that empty range into a non-empty location.