1. A tomographic reconstruction method for reconstructing a 3D image object corresponding to a data set, the method comprising: providing a pixon map; for each step in a series of iteration steps, determining an updated object by performing a combined operation including performing an update operation for updating an input object, and performing a pixon smoothing operation for smoothing based on the pixon map; and following a last iteration, outputting one of the updated objects as the 3D image object.