1 0 0 0 1 0 0 0 1 / Norm (L2-norm of gradient) 1. 0. 1. 0. 0. 0. 2 0 0 0 2 0 0 0 2 0 1 1 1 0 1 1 1 0 / Isotropic 1 .333333 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1.333333