In one embodiment of the present invention, a method for processing a 2D or 3D reconstruction image is disclosed which is recorded by a magnetic resonance device, including a gradient coil that generates a gradient field, and is distortion--corrected with regard to a given non-linearity--leading to an image distortion--of the gradient field using an algorithm that processes the measurement signals at different measurement points lying in the imaging volume, which algorithm, with respect to each signal processed by it, processes the first input value describing the real gradient field given at the real measurement point of the signal, in which method, for inverse transformation of the distortion-corrected reconstruction image into a distortion-uncorrected reconstruction image, use is made of the first algorithm or a second algorithm corresponding to the first algorithm, which, with respect to each signal processed by it, is given as second input value such a value which describes a fictitious gradient field at the respective distorted measurement point at which the processed signal appears, which is increased or decreased by the non-linear field component of the real gradient field compared with the linear ideal gradient field.