An apparatus for generating assignments between image regions of an image of an object and element classes includes an assigning unit (13) for assigning element classes to image regions of an element image of the object, which is indicative of a distribution of the element classes, depending on region and/or boundary features, which are determined depending on image values of a provided object image and provided first preliminary assignments. Thus, the resulting element image with the assignments to the element classes is not necessarily based on the provided object image only, but can also be based on the provided preliminary assignments. If the quality of the assignments defined by the element image would be restricted due to restrictions of the provided object image, these restrictions of the provided image can therefore be compensated by the preliminary assignments such that the quality of the resulting element image can be improved.