Even when a high-performance imaging apparatus is not used, luminance unevenness and color unevenness of an image (video) projected on a projection plane by the projection type projector apparatus are appropriately reduced. Using a coefficient Br (0≦Br≦1) set by a coefficient setting unit, the projection system obtains, based on the gamma characteristic of the entire system of the projection system, a target image for reducing the number of pixels saturated when the image is projected. Then, the projection system performs correction processing using the obtained target image based on the gamma characteristic of the entire system of the projection system and a white value. This reduces the number of saturated pixels of the projected image in the projection system. Furthermore, even in a case or similar cases when a captured image obtained by capturing a projected image has a bad S/N ratio, image projection processing that does not cause a user discomfort in viewing the projected image (or captured image) is achieved.