Hybrid image processing using optical defocusing and digital computing techniques is investigated for use in the analysis of interferograms or moire fringes. The optical thickness distribution of a glass plate is measured from the interferogram, and the power distribution of an eyeglass lens is tested from the moire pattern. The optical defocusing technique is also used for preprocessing of the input image to suppress high frequency noises. The optimum defocus amount relating to the processed result is discussed.