1. An image processing device, comprising: an imaging unit configured to obtain an input image by imaging a subject; an image synthesizing unit configured to generate a synthetic image by superimposing an icon and the input image; a recognition unit configured to recognize a first object in the synthetic image using a registered image of the first object stored in the image processing device; an image correcting unit for correcting at least one of the luminance of the first object and the luminance of the registered image, such that the luminance of the first object is equal to the luminance of the registered image; an image comparing unit configured to detect, based on the registered image, a first area of the synthetic image where the first object overlaps with the icon, wherein the image comparing unit detects the first area based on a difference between a luminance of the first object and a luminance of the registered image; and a display control unit configured to position the icon in a second area of the synthetic image other than the first area such that the icon does not overlap with the first object.