A multicolor-printer has at least a first and a second print station, first and second optical sensors and a surface recordings comparator. The first and second print stations are arranged to print images on a surface of a moving recording medium. The first and second optical sensors view, at the first and second print stations, an area of the recording medium surface to obtain at least one first surface recording, in a manner related to the first print station's image printing, and second surface recordings, respectively. A storage is arranged to store the first surface recording. The surface recordings comparator is arranged to test, during the recording medium movement, for correspondence of second surface recordings with the stored first surface recording. The printer is arranged to repeatedly, within one image, register raster lines of the image of the second print station to corresponding raster lines of the image of the first print station in response to correspondences found between the first and second surface recordings.