1. An image projection apparatus comprising a projection unit to project a pattern image on a projection surface; an image capturing unit to capture the projected pattern image; a corrector to correct the captured image so that an imaging distortion, caused due to image capturing, and a projection distortion, caused due to projection, are corrected; and a combiner to generate a composite image by combining the pattern image and the corrected captured image, wherein the projection unit is further configured to project the corrected captured image at a position on the projection surface and is further configured to project the composite image so that the corrected captured image locates at the position, and wherein the position is a center of a lower part of the projection surface, and the combiner is further configured to generate the composite image in which the corrected captured image is combined at the center of the lower part of the pattern image.