This paper presents an automatic approach for the evaluation of isochromatics and isoclinics in photoelasticity using complementary phase shifting. First, the phase values of the isoclinics are obtained from four images in the plane polarizer arrangement by rotating the polarizer and analyzer simultaneously. Then, through use of the isoclinics, a full-field description of the first principal stress orientation with respect to the horizontal axis is determined. Phase maps for the isochromatics are then achieved at eight discrete orientations through sequential analyzer rotations. With the first principal stress orientation known from the isoclinic phase map, a whole-field description of the phase values of the isochromatics is then constructed. The proposed method was validated for the problem of a ring under diametrical load.