In coherent optical data processing, the optical system is used as a linear space invariant system. A method in which the optical system is highly space variant was described recently l. With this method, a geometric transformation of an object can be obtained in the frequency plane of the object. The optical component responsible for the geometric transformation is a computer-generated phase filter. In this paper, we shall briefly describe this method of optical map transformation. Because of the importance of the phase filter in the optical system, we will also discuss a recent method for making computer-generated holograms2. An example is presented which shows how conformal mapping is achieved with this optical technique.