1. A projector, comprising: an image projector to project an image; a set of inherent parameters including a horizontal resolution Wn 0 , a vertical resolution Hn 0 , a depth d, and a vertical offset db; a receiver to receive a vertical tilt angle βv and a horizontal tilt angle βh; and a corrector to compute keystone correction corner points for the image using the set of inherent parameters, the vertical tilt angle βv, and the horizontal tilt angle βh, so that the image can be corrected internally to the projector.