A method for despeckling the image reproduced by a Computer Generated Hologram (CGH) including reproducing a CGH, and jittering a location of an exit pupil of an optical system through which the CGH is imaged, relative to an observer's input pupil, so as to shift at least some speckles out of the exit pupil. A method for despeckling a Computer Generated Holographic image including computing a first modulation for a first holographic image, and computing a second modulation for a second holographic image of a same holographic image using an initial phase distribution used for calculating the first holographic image as an initial phase distribution used for calculating the second modulation. Related apparatus and methods are also described.