1. An image output apparatus comprising: an effect degree calculation means for calculating the degree of effect in a corrected image, obtained by performing correction processing on a region that requires correction, in a photographed image obtained by taking a photograph of a subject; a check requirement judgment means for judging, based on the magnitude of the degree of effect, whether it is required to check the effect of correction processing performed on the photographed image; a check display means for displaying at least one of the photographed image and the corrected image to check the effect of correction processing, if the check requirement judgment means judges that it is required to check the effect of correction processing performed on the photographed image; an image output instruction means for instructing output of the corrected image after at least one of the images is displayed to check the effect; and an image output means for outputting the instructed corrected image.