Abstract: This paper puts emphasis on the measurement and the applications of MTF of the photographic system. Two filtering methods, i.e. the spatial domain filter and the speetral domain filter, have been compared and the result shows that the spectral domain filtering method is practical and effective. With regard to its, the paper proposes using the equivalent width of line spread function (EQW) as an image quality evaluating stan dard) the tests indicate that there is certainly similarity between 1/EQW and the resolution of the photograph. A tentative study of copy quality has also been made.