A useful expression for the complex amplitude of the reconstructed holographic image is derived. This expression shows how the reconstructed image is affected by the optical transfer function of the recording media and by the size and shape of the hologram. Special cases that are studied include perfect film, very good film, Fourier-transform holograms, and large holograms. Detailed solutions for the general case are obtained by assuming a gaussian optical transfer function and either a rectangular hologram aperture or one having gaussian weighting.