A system and method for correcting distortion in projected images caused
by the projection of an input image by a projector lens onto a projection
screen having a surface that is not orthogonal to the projection axis of
the projector. Projection parameters including the focal length of the
projector lens and the angles that represent the pan, tilt and roll angle
of the projector are obtained. Then the projected area and the best
viewable rectangular area that fits within said projected area is
determined. The distortion is then characterized by using a distortion
transformation which corresponds to the transformation that exists
between the vertices of the best viewable rectangular area and the
corresponding vertices of the projected area. Finally, the distortion
transformation is inverted and applied to input image to obtain a
distortion free projected image.