1. An imaging apparatus for imaging an object, the imaging apparatus comprising: a projection data providing unit for providing energy projection data values, the energy projection data values being energy-dependent and corresponding to rays, which have been emitted by a radiation source and which have traversed the object and a beam shaper placed between the radiation source and the object, a reconstruction unit for reconstructing an image of the object based on the provided energy projection data values, wherein the reconstruction unit is adapted to: determine component projection data values, which correspond to the rays after having traversed the object and which correspond to a component of the object, by combining weighted base functions, which depend on the provided energy projection data values, wherein a component projection data value, which corresponds to a ray, is modeled as a combination of weighted base functions, wherein a base function depends on a product of intermediate base functions, where a first intermediate base function depends on the energy projection data values and a second intermediate base function depends on the length of the respective ray within the beam shaper, reconstruct an image of the object based on the determined component projection data values.