An image signal source alternately outputs two types of image signal. A pixel shifting unit outputs an image as light displayed by a display element having a number of pixels corresponding to the image signal while alternately shifting the light by a distance of a ½ pixel horizontally and a ½ pixel vertically. A horizontal display control unit receives the image signal and, in response to an installation position, changes the received image signal so that an image corresponding to any one of the two types of image signal alternately outputted is horizontally shifted by one pixel. A display element drive unit receives the changed image signal and, in response to the installation position, controls the display element so that the display element displays an image obtained by horizontally inverting the image based on the received image signal.