1. A pointer light tracking method for shooting pointer light projected on a display by a camera to track the pointer light on the display by a computer based on the obtained image data, comprising: projecting an all black image and white square images located at four corners of the all black image on the display; shooting a display where the all black image and the white square images are displayed; extracting a domain corresponding to the white square image from the obtained image data; computing central coordinates (x, y) of the extracted domain; and computing a parameter which is needed at the time of performing distortion correction by use of projection conversion for a coordinate expressing a position of the pointer light on the display from the computed central coordinates (x, y) and the central coordinates (X, Y) of the white square image.