A method for determining image values in marked pixels of at least one projection image is provided. The at least one projection image is part of a projection image set provided for reconstruction of a three-dimensional image dataset and acquired in each case using a projection geometry in an acquisition procedure. The image values are determined through evaluation of at least one epipolar consistency condition that is to be at least approximately fulfilled, that results from the projection geometries of the different projection images of the projection image set, and that requires the agreement of two transformation values in transformation images determined from different projection images by Radon transform and subsequent derivation as a condition transformation.