1. An image projecting system comprising: a plurality of projector apparatuses that project images based on inputted image signals onto a screen so that the images are displaced relative to one another by a predetermined amount and superimposed; an observation apparatus that observes luminance of an image region composed of a plurality of projected images that have been projected onto the screen; and a control apparatus that supplies to the plurality of projector apparatuses the image signals in which a luminance value of each pixel that constructs an image to be projected by each projector apparatus has been adjusted based on an observation result of the observation apparatus, wherein the image region composed of the plurality of projected images is presented by superimposing a first projected image and a second projected image that has a higher resolution than the first projected image, and wherein predetermined pixels in the image region are presented by superimposing corresponding pixels in the projected images from n adjacent projector apparatuses (where n is an integer of two or higher).