CODEWITHSUNDEEP
matlabimage-processingconvolution
HforHisham
HforHisham

Reputation: 1964

Create the 2D blurring matrix in matlab

I can apply a filter on an image I by the following code:

h = fspecial('gaussian',20,4);
blurred = conv2(I,h,'same');

The size of the image I is the same as of blurred, I want to write the process of convolution in matrix multiplication form i.e. blurred=H*I(:) so i tried the following:

 H=convmtx2(h,size(I));
 blurred=H*I(:);

but the size of blurred after reshaping will be larger than of I because convmtx2 return a full convolution matrix, How can i get a convolution matrix that will return only the central part not the full convolution.

Upvotes: 1

Views: 2099

Answers (1)

Divakar
Divakar

Reputation: 221514

See if this works for you -

h = fspecial('gaussian',20,4);

H=convmtx2(h,size(I));

I_conv = reshape(H*I(:),size(h)+size(I)-1);
s1 = round(size(h,1)/2);
blurred = I_conv(s1+1:s1+size(I,1),s1+1:s1+size(I,2));

Upvotes: 2

Related Questions