A method of controlling a printer is disclosed, the printer including a number of print heads extending across a print zone, and each print head including at least one nozzle array extending in a direction of a print head axis. Each nozzle array comprises a center section of nozzles and side sections of nozzles, wherein the side sections of neighboring nozzle arrays overlap defining an overlap region and the center sections of the nozzle arrays define non-overlap regions. The method includes: printing a test pattern using at least two nozzle arrays, the test pattern comprising an interferential-type pattern printed by the side sections of the nozzle arrays in the overlap region and a reference pattern printed by the center sections of the nozzle arrays in the non-overlap regions; detecting characteristics of the printed test pattern; comparing the characteristics of the printed test pattern in the overlap region and in the non-overlap region; and deriving information concerning the alignment of nozzle arrays from the comparison.