A printing system includes a substrate support, a printhead assembly positioned facing the substrate support, and an imager. The printhead assembly includes a plurality of dispensing nozzles extending in an ejection direction towards the substrate support and a plurality of marks. The imager is movable relative to the printhead assembly and oriented in a direction opposite to the ejection direction for capturing at least one image including the plurality of marks indicating positions of the plurality of dispensing nozzles in the printhead assembly.