1. An image processing device for combining a current image of an object and a map image of a dwell region of the object, comprising: a memory for storing a number of map images which are categorized according to a varying state of the dwell region of the object; a monitor for displaying a combination of the current image and a section of the map image, wherein the current image and the map image are from different imaging source; and a data processor arranged: a) to select one of the map images most closely categorized by a current state of the dwell region in which the current image is generated, b) to estimate the position of the object in the current image in relation to a section of the map image most closely categorized by the current state, the section of the map image most closely categorized by the current state of the dwell region just covering a region around the estimated position of the object, and c) to combine the section of the map image most closely categorized by the current state of the dwell region around the estimated position of the object in the current image, the estimated position of the object in the section of the map image most closely categorized by the current state of the dwell region being brought into registration with the actual position of the object in the current image; such that the monitor displays the current image with the section of the map image most closely categorized by the current state of the dwell region which just covers the region around the object combined with the corresponding region of the current image.