1. An image processing device comprising: an acquisition unit configured to acquire a tomographic image of a retina of an eye to be examined; and a generating unit configured to generate a new tomographic image, using a reverse image in which at least one portion of the acquired tomographic image is reversed and the acquired tomographic image, so that the reverse image is located on a side on which a retinal layer in the acquired tomographic image is in contact with an end of the acquired tomographic image.