Abstract: An image reproduction apparatus for connection to a network for printing print jobs, includes a printer unit for making images on receiving sheets, a user interface unit provided with operating elements, and a control unit for controlling printing processes and adapted to interrupt an active printing process in response to an interrupt command given via the user interface elements. The control unit is provided with a first module to check whether a print job fed via the network contains a predetermined added data item, and a second module for carrying out an authorization check in respect of any interrupt command input during the performance of a certain print job, if the first module detects the presence of such a predetermined added data item in the print job.

Abstract: Temporal changes in an object are detected by focusing light from preselected spatial locations of the object on associated first and second regions of a light sensitive target at first and second times, respectively, and by comparing the light intensity focused on the regions. The focusing apparatus includes a Ronchi grating located at an image plane between the object and a light sensitive target. At the first time, light from the object passes through the clear portions of the grating to illuminate alternate parallel stripes on the target, while at the second time, the light passing through the clear portions is shifted to illuminate the regions between the first parallel stripes. The target is then scanned, and information from associated stripes is compared to detect changes. In one embodiment, the shaft can be brought about by the use of a birefringent crystal and polarized light; alternatively, a beam splitter and a shutter arrangement can be used.