Lets see..
Lets assume for the moment you use a mouse click on the image, every time you do this you can record the
Point using a Tpoint. This gives you the starting point and you should record to what the scrollbox.client locations are
not the timage using the MOUSE record, this gives you screen coordinates.
As you process the mouse moves while the mouse is being held down, you then take another reading from the
MOUSE record, calculate the offset difference in movement from the starting point when you initiated the click.
Reposition the Timage Left,Top using the these offsets + or - and you'll get your panning effects..
Just remember that when you release the mouse, you need to restore the LEFT,TOP of the timage back to 0,0
or where ever you want it.