Imaging covers a broad range of techniques and scientific fields, from classical phase-contrast X-ray imaging to coherent X-ray diffraction imaging (CXDI) and with applications, e.g. in strain imaging inside nanostructured materials to bio-imaging of whole cells. In many cases the aim is to obtain a 3D representation of the investigated structure. By phase retrieval methods it is possible to pass from the measured diffraction patterns in reciprocal space to a real space visualization of the scattering object.