Method for adjusting the print repeat length of a print image in a multicolor rotary printing machine

A method of adjusting a print repeat length of a print image in a multicolor rotary printing machine having a first plate cylinder and a second plate cylinder,

• the first plate cylinder and the second plate cylinder being associated with a shared central impression cylinder which conveys a print substrate, and
• a peripheral velocity of the first plate cylinder and a peripheral velocity of the second plate cylinder being adjusted relative to a peripheral velocity of the central impression cylinder, said method comprising the steps of:
• modifying the peripheral velocity of the first plate cylinder and the peripheral velocity of the second plate cylinder during a printing operation, relative to the peripheral velocity of the central impression cylinder;
• adjusting a longitudinal register of the first plate cylinder having the modified peripheral velocity and a longitudinal register of the second plate cylinder having the modified peripheral velocity,
• with the step of modifying of the peripheral velocity and the step of adjusting of the longitudinal register being effected simultaneously;
• and
• employing a control and/or regulating program having a procedure for controlling the peripheral velocity and having a procedure for controlling the longitudinal register, and calling the procedure for controlling the longitudinal register simultaneous with calling the procedure for controlling the peripheral velocity, with a modified value of the peripheral velocity being a basis for a new control value.