Abstract: The SIMS channelplate used for recording image signals is characterized by local sensitivity differences caused by increasing aging of the central channelplate regions, which are subject to much more intense ion bombardment than the outer regions. These sensitivity differences lead to inhomogenous illumination of the sample, i.e., to images with disturbed intensity distributions. We present here a novel method to correct these illumination discrepancies by using the intensity changes due to sample position shifts to find the interfering background function that can be used to correct the original image. The proposed method has low presuppositions about the regarded images, and is stable with regard to noise and easy to apply. It is suitable not only for correction of channelplate local sensitivity differences but for all sorts of microscopic images that suffer from illumination inhomogeneity.