design my own 2d filter

I'm wondering is there a way to define my own 2d filter. Assuming there is a matrix A, I'd like to assign every element of A to the maximum value of its 8 neighbors. For example:

A = [1 2 3 4 5
     6 7 8 9 10
     -1 3 4 8 13
     4 2 0 9 1]
After filtering:

A = [1 2 3 4 5
     6 8 9 10 10
     -1 8 9 13 13
     4 2 0 9 1]

Thanks