1. An image processing device comprising: an object detection processing unit configured to detect, by performing pattern matching between an image to be processed and a reference image of an object, the object in the image to be processed, while changing the relative angle of the images; an object-image orientation identification unit configured to determine the top and the bottom of the image corresponding to the top and the bottom of the object, based on the relative angle at which the object is detected by the object detection processing unit, so as to identify a correct orientation of the image; and an image-data updating unit configured to update data of the image so that the image is displayed in the identified orientation.