In a method to control a printer or copier, a color measurement unit is provided for determining a measurement value of a print marking in a measurement region of color measurement unit. The print marking is printed on the printing substrate web. In addition a positioning marking is also printed on the printing substrate web in a predetermined position relative to the print marking in order to determine a relative position between the print marking and the measurement region of the color measurement unit. The positioning marking comprises at least two partial regions printed in different colors, the partial regions being formed such that a determined color value of the positioning marking changes given a movement of the measurement region of the color measurement unit transverse to a movement direction of the printing substrate web. A real color value is determined with the color measurement unit if the measurement region of the color measurement unit is arranged in a region of the positioning marking. A relative position between the print marking and the color measurement unit is determined depending on a real color value. The measurement value of the print marking is determined and the printer or copier is controlled depending on the measurement value of the print marking.