At least one register and an ink density are controlled in a printing machine having at least one printing unit which includes a forme cylinder, a transfer cylinder, and a counter-pressure cylinder. An image sensor records an image from a print substrate, which is imprinted with ink, inside the printing unit, and sends data correlated to that image to an evaluation unit. The data for the last printed image is compared with prior data and in response, the evaluation unit generates a command that is directed to an actuator for controlling the supply of ink. The image sensor is oriented towards the print substrate and detects the entire width of the printed substrate, which width is transverse to a direction of substrate conveyance. The evaluation unit generates the actuating command to control the supply of ink based on data from the image sensor and taken over the entire width of the substrate. The evaluation unit also controls register, based on this data. The forme cylinder has a separate drive which can be controlled separately or that can be regulated by the counter-pressure cylinder assigned to it.