Apparatus and method for adjusting video display

An adjustment apparatus for a video display system, comprising:

• a display member for displaying a video image on a rectangular video display screen enclosed by a rectangular frame;
• an image input member for detecting an entire rectangular area of said display screen including detecting four corner positions of the rectangular frame and producing an output signal representing said display screen;
• a memory member for memorizing the output signal produced by said image input member;
• a calculating member connected to said memory member for calculating coordinates for the four corner positions detected by said image input member and calculating a plurality of reference positions within the area of the display screen member based upon calculated four corner coordinates, said plurality of reference positions being stored in said memory means;
• a signal generating member for generating a video signal having a pattern corresponding to said plurality of reference positions from said calculating member and displayed on said display screen by said display member, said image input member detecting said pattern and producing an output for storage in said memory member, whereby said calculating member calculates an adjustment value for adjusting said display member by comparing the stored reference positions and the stored detected pattern;
• and
• a system control member for controlling operations of said signal generating member, said memory member, and said calculating member.