Since the introduction of grating interferometers to imaging, in addition to attenuation contrast, differential phase and later also dark-field contrast imaging have been explored intensely. However, in particular with dark-field contrast imaging, imaging entered into a new domain, i.e. the scattering from sub-image-resolution structures. This has led to the need to expand the horizon of considered interactions into the reciprocal space domain of small angle scattering, not necessarily familiar in real space imaging. Correspondingly, description and interpretation and finally quantitative analyses lacked somewhat behind of on the other hand qualitatively invaluable results. Against this background all modalities measured in modulated beam imaging experiments, namely attenuation, differential phase and dark-field contrast, shall be given some additional attention. It will be undertaken to draw a clear picture of analogies, of contrast formation and consequences to interpretation and information content.