I once worked as part of a team which had graphics people who were allergic to the command line.

Of course there are some things for which Gimp/Photoshop is really necessary, but it turns out that there is a massive amount of image manipulation that is better done on the command line than within Photoshop. The people who were dependent on Photoshop would take endless hours completing the same tasks which can be done in seconds using the command line.

some crazy image-magick fu here.