1. A computer-implemented method of reconstructing an image object for a measured object in object space from image data in data space, the method comprising causing a computer system to execute instructions for: providing zonal information separating the object space into at least two zones; providing at least two zonal image objects, each zonal image object being associated with one of the at least two zones; performing a zonal smoothing operation on at least one of the zonal image objects, thereby generating at least one smoothed zonal image object; reconstructing the image object on the basis of the at least one smoothed zonal image object; and outputting the image object.