Image Coordinates Screen

There are two formats for the display: corners or center-mag. You can
toggle between the two.

In corners mode, corner coordinate values are entered directly. Usually
only the top-left and bottom-right corners need be specified - the
bottom left corner can be entered as zeros to default to an ordinary
unrotated rectangular area. For rotated or skewed images, the bottom
left corner must also be specified.

Center-mag mode can only be used with unrotated unstretched images.
In this mode the image area is described by entering the coordinates for
the center of the rectangle, and its magnification factor.