A camera or image formatting unit that is a component of a diagnostic imaging system used to imprint identifying marks on: 1) photographic film or x-ray film (by exposure to visible light); or 2) digitally, on images created using various diagnostic imaging modalities [e.g., magnetic resonance imaging (MRI), x-ray or nuclear medicine]. Depending on the design of the marking system, it may be electronically or computer-controlled. Most frequently, it is used to imprint information on the images related to image acquisition parameters, patient identification, and to record anatomical information on individual images.