To perform speedy imaging of a printing form by an imaging apparatus which includes a laser diode bar of (n) laser diodes and one laser diode or more of which are stopping.

The imaging apparatus includes the laser diode bar 14 having seven individually controllable laser diodes 16 whose imaging spots (20) lie essentially in a row at intervals (a) on the printing form (10). One laser diode 16 can not be activated, but the six laser diodes 16 can be activated. The relative speed between the imaging device 12 and the printing form 10 is increased by the factor (n/m). The exposure time per printing dot is shortened by the factor (m/n). In order to input in each case an amount of energy per printing dot on the printing form 10, imaging is carried out using the six activatable laser diodes 16 with an imaging intensity which is a function of the exposure time and of the specific amount of energy per printing dot 69.