A graphical user interface (GUI) graphically corresponds to an image display window through which a single image or a stream of images or video frames are displayed. The GUI includes a zoom control box having an inner region positioned within an outer region. The size of the inner region relative to the outer region represents the magnification of the portion of the image being displayed within the image display window. The magnification of the image being displayed is increased by using a cursor control device to position a cursor within the inner region and clicking the cursor control device. The magnification of the image being displayed is decreased by using the cursor control device to position the cursor outside of the inner region but inside of the outer region and clicking the cursor control device. As the magnification is increased or decreased, the size of the inner region relative to the outer region is changed accordingly. A magnification factor is also displayed within the inner region to display a numeric representation of the current magnification. The position of the inner region within the outer region represents the portion of the entire image being displayed within the image display window. The portion of the image being displayed within the image display window is changed by clicking and dragging the inner region to the desired position within the outer region using the cursor control device.