T = convmtx2(H,m,n) returns the convolution matrix T for the matrix H. If X is an m-by-n matrix, then reshape(T*X(:),size(H)+[m n]-1) is the same as conv2(X,H).T = convmtx2(H,[m n]) returns the convolution matrix, where the dimensions m and n are a two-element vector.
T = convmtx2(H,m,n)T = convmtx2(H,[m n])
You can give an example if you know one.