Abstract: A printing machine comprises an X-Y table (50) for moving a substrate (30) with respect to a print head (20). During a printing process, the substrate (30) is moved, whereas the print head (20) is intermittently activated to fire ink droplets. A camera (25) is arranged for providing images of the substrate (30) to a computer which is programmed to recognize patterns. In order for the print head (20) to be able to print a spot at a predetermined position on the substrate (30), an offset between a predetermined and an actual mutual position of the substrate (30) and the print head (20) is measured and compensated for. For the purpose of measuring this offset, a test spot (38) is printed on the substrate (30) and an offset between a predetermined and an actually obtained position of this test spot (38) is measured by means of pattern recognition.