An image processor includes a first converter to convert input images into images in a different coordinate system from that of the input images according to first conversion data based on a projection model, a position detector to detect a connecting position of the images converted by the converter, a corrector to correct the first conversion data on the basis of a result of the detection by the position detector, and a data generator to generate second conversion data for image synthesis from the conversion data corrected by the corrector on the basis of coordinate conversion, the second conversion data defining the conversion of the input images.