1. A method for tracking a laser spot on a projected computer screen image, said method comprising: electronically capturing said projected computer screen image on a projection surface in a frame of image data; fitting a polygon to a contour of each graphical object in said frame of image data; determining whether said polygon for each graphical object satisfies a set of predefined parameters to find a candidate polygon that corresponds to an outline of said projected computer screen in said frame of image data; and computing a projective transformation matrix using corners of said candidate polygon, said projective transformation matrix including mapping information to track said laser spot on said projected computer screen image.