The invention is related to processing x-ray imaging data, specifically phase contrast x-ray imaging data, and addresses the problems associated, for example, with vibrations in grating-based differential phase contrast imaging by making use of spectral information. It was realized that one may make use of the spectral information in determining the vibration state of the Moire pattern based on multi-energy-bin x-ray detectors, the energy independence of vibration-induced Moire pattern phase shifts, the energy dependence of object-induced Moire pattern phase shifts and a phantom designed to allow for measuring the dependence of the object-induced phase shift as a function of the energy bin. In particular, it was found that by suitable data processing the vibration-induced shifts and the like can be disentangled from the object properties and hence vibration artifacts in the image are reduced, while there is no particular need for changing the basic physical structure of the imaging device.