1. A method for forming a mosaic image on a display surface with a plurality of projectors, comprising: projecting, for each projector in turn, a registration image onto the display surface so that a union of the projected registration images forms a polygon; acquiring with a camera, for each registration image in turn, a corresponding input image; identifying a display area on the display surface enclosed by the polygon; determining, for each projector, a single projective matrix between the display area and each input image; warping, for each projector, a source image according to the corresponding single projective matrix; weighting pixels of the warped source image according to the single projective matrix; and concurrently projecting the warped and weighted source images directly onto the display surface to form the mosaic image.