A method and an apparatus are provided for correcting geometric errors during a transfer of a printing image to a printing material. For the purpose of correction, a raster bitmap is fed to a matrix manipulation device, which distorts the raster bitmap. The problem with the distortion is that areas such as edge marks are also distorted. In order to avoid those undesired distortions, a protected area determining device for determining a protected area within the raster bitmap and/or the master print, and a protective element for preserving the content of a protected area within a raster bitmap, are provided.