1. An image processing device comprising: a stereoscopic image supply unit configured to supply a stereoscopic moving image in which stereoscopic image pairs each including two images of an object viewed from mutually different viewpoints are arranged in a temporal order; a synthetic image generation unit configured to generate a synthetic image in the temporal order by performing a predetermined operation on luminances of the two images; and an output image selection unit configured to sequentially select and output any one of the two images and the synthetic image in the temporal order so that a result of a time integral during a predetermine period of an output thereof offsets any one of the two images.