Hiding the image boundary prevents the boundary from being plotted or displayed.
Also, hiding the image boundary prevents you from selecting the image with the pointing
device, ensuring that the image cannot accidentally be moved or modified. However,
images can still be selected if they are not on a locked layer, for example, if the
image is part of a named selection set made with the All option. When image boundaries
are hidden, clipped images are still displayed to their specified boundary limits;
only the boundary is affected. Showing and hiding image boundaries affects all images
attached to your drawing.