Abstract: A scanning device movable with respect to an original is provided for scanning the latter. An optical system focuses the light emitted by a region of the original on a plurality of photo-sensors, the output signals of which are then amplified, selectively inverted, and added. The summed up signal thus obtained is input into a processor which generates a driving signal for controlling a stylus which moves in synchronism with the original relatively to a printing cylinder, and engraves on it an image of said region. The response of the photosensors to light which issues from different parts of the region can be regulated by means of optical filters having locally varying densities.