In display holography, when the reconstruction wavelength or geometry differ from those of recording, the image is, in general, distorted and aberrated. These variations from the original object are hard to predict using the usual optical equations, which are best suited to imaging systems where the pupil of the system is known a priori. Here I describe the latest features of a computer program (HoloPov) developed to predict and to graphically display the distortions and aberrations in display holograms. The program has an easy to use graphical user interface, and can produce animations.