1. An automatic video window generation system comprising: a source of video signals containing successive frames of images of a target; processing means for resizing a window which bounds an object image in said video signal by executing the steps of: determining which lines of video signal contain the object image based on the density of pixels contained in said video signal; determining a length of each of said lines containing said object image; determining the principal orientation of said target image from the from said lines; shifting the starting and ending points of said lines in accordance with said principal orientation to define the width of said window in a subsequent frame; and determining a vertical size for said window by determining which lines of said video signal contains said target image.