The theory of modulation transfer function(MTF) has an important status in restoration technique. Generally, it is not feasible to resolve MTF because the MTF depends on a very large number of time and space varying factors. Therefore a approximate MTF is often used in image restoration. In this paper, the authors describes a model of computing MTF from edge curve based on original images, and the methods of extracting edge curve and image restoration processing both in frequency domain and spatial domain are explained. The experiments confirm that MTF theory has great potentiality in image restoration.