An intensity-based image processing method termed the Intensity Integration Technique (IIT) is proposed to obtain the slope and curvature of loaded reflecting plates. It employs divergent beam illumination to cover a large plate area. The deformation field is established by applying cumulative (integrated) intensity as the correlation parameter to relate the reflected images from the undeformed and deformed states of the object. The method is suited to modern computing environment and requires a simple experimental set-up. It obtains absolute values of slope and curvature.