Method of preventing a registration error while printing

Method of preventing a registration error while printing at least one printing image, wherein, in order to control or adjust the correct length of the printing image, the start and/or the distance of the printing image lines of the printing image are controlled by determining the ratio of the number of rotary encoder signals of a transport web counted during a specific time interval, said transport web transporting the printing sheets, to the number of rotary encoder signals of a cylinder of a printing unit detected during the same time interval, said cylinder participating in the printing operation and moving directly or indirectly with the transport web, and by taking into account a change of this ratio as a correction, said ratio being a function of a printing sheet located in a printing nip between the transport web and the printing unit, and whereby, in order to achieve the desired registration accuracy, a certain mean value of time is determined by way of determining said ratio,

• wherein a changed printing material situation occurring in said printing nip between the transport web and the printing unit is used to achieve registration accuracy by immediately taking into consideration a correction value that takes into account the changed printing material situation.