The full-filed evaluation of the isoclinic parameter in digital photoelasticity is presented. The proposed method is based on the four-step color phase shifting technique and the phase unwrapping (PU) algorithm. It is experimentally applied to an eccentrically loaded split ring (C-shaped model). Experimental results show that the isoclinic-angle map obtained is almost free from the influence of the isochromatic parameter and the isoclinic values lie in the physical range, -π/2 to +π/2, regardless of the presence of the isotropic point or region.