In addition to reloading the full resolution subwindow with the ``Load'' button on the subwindow, it is also possible to trigger a load operation with a Ctrl - Middle mouse button operation in the subwindow. The load operation actually goes back to the original image file on disk to reload the requested subarea.
The subwindow is also resizable, allowing the user to decide on how large a subwindow area to view. As the subwindow size is increased, it takes longer to reload because of the larger amount of data to fetch; however, the user can see a larger area, which may be important for establishing enough image context to identify a position in the greater image. The other trade off in making the subwindow larger is the difficulty in fitting all of the windows on the screen at once.
Normally, the overview window is used to establish the area of interest before loading full resolution data into the subwindow. Then GCPs or mosaic cut lines can be collected in the subwindow where full resolution data is available in order to achieve maximum accuracy. However, it is also possible to collect GCPs and cut lines in the overview windows.