which is the NIM potential vector associated with clique types, respectively. We observe that the NIM potential vector is in a quadratic form. The quadratic assumption is widely used to model images in numerous problems [12] and is called the Gaussian MRF (GMRF) model. GMRF models are suitable for describing smooth images with a large number of intensity levels. Furthermore, under thisGMRFmodel, (19) can be solved more easily due to the fact that the summation over configuration space in (17) changes to infinite integration in product space. Hence, the analytical solution for (19) can be derived. Using the GMRF model [14], [15], we can rewrite (20) as