In a method and device to control a print process in a printer or copier, with a character generator generating a latent print image and a latent toner marking on an image carrier. An exposure energy per unit area for the generation of the latent toner marking is decreased in comparison to an energy per unit area for generation of the latent print image. The latent print image and the latent toner marking are developed with toner in the developer station. An optical reflection sensor determines color density of the developed toner marking. Toner concentration is adjusted in a developer station dependent on a signal of the reflection sensor.