In an image viewing system, a medical image (50) is displayed on a display panel (18) having a predetermined aspect ratio. One of a horizontal orientation and a vertical orientation in which the display panel is positioned is detected. A longitudinal direction of the display panel is vertical in case of the vertical orientation, and is horizontal in case of the horizontal orientation. The medical image is processed in rotation processing relative to the display panel by maintaining a size of the medical image in compliance with one of the horizontal and vertical orientations of the display panel, to orient the medical image in a proper orientation relative to a viewing direction to the display panel. Assuming that a blank area (52) is created outside a display area of the medical image on the display panel after the rotation processing, relevant information (54, 56) relevant to the medical image is displayed in the blank area.
