The imaging properties of coherent optical systems where images are formed as reconstructions from volume holograms are investigated. The apparent modulation transfer functions for a given optical system are determined for various imaging and reconstruction conditions, theoretically and experimentally. A model describes the formation of the image from the coherent superposition of three amplitudes. It is shown that a thin rectangular absorption grating is a suitable object for deducing the modulation transfer of the equivalent three-amplitude object from the measured intensity distribution of the grating image. These real modulation transfer functions are compared with the calculated ideal ones; this comparison represents a measure for image quality.