A system for presetting register and color zone adjusting devices in a multi-color rotary printing machine uses digitally-driven optical scanners axially traversing the plate cylinders under control of at least one numerical computer. Machine-specific characteristics are programmed in non-volatile memory as referenced values. Data processing is not required to be conducted external to the printing machine. The system is compact and requires practically no re-adjustment or entry of desired values from the machine operator. The machine operator, however, may enter coordinates for printing areas on the printing plate in order to speed up the scanning process for determining the initial color zone preset. The scanner multi-functionally scans the printing plate for both register adjustment and for integrating the ratio of printing to non-printing area for each inking zone. The system is easily reprogrammed and the optical scanner is interchangeable with a densitometer in order to provide alternative control functions during printing, such as the regulation of inking and dampening.