1. A method of utilizing an optical image processing system, the method comprising: (a) providing to the optical image processing system a measured magnitude of the Fourier transform of a complex transmission function of an object or optical image, wherein the complex transmission function equals or approximates a minimum-phase function or a maximum-phase function; (b) providing to the optical image processing system an estimated phase term of the Fourier transform of the complex transmission function; (c) using the optical image processing system for multiplying the measured magnitude and the estimated phase term to generate an estimated Fourier transform of the complex transmission function; (d) calculating an inverse Fourier transform of the estimated Fourier transform, wherein the inverse Fourier transform is a spatial function; and (e) calculating an estimated complex transmission function by applying at least one constraint indicative of a known property of the complex transmission function to the inverse Fourier transform by making the inverse Fourier transform conform to the known property.