Fit to screen option for poster view

What I would like to see as an option to make the poster viewer fit to the height of the screen, or add scroll bars so that one can scroll through an image (or both options) so that large images can be viewed in their entirety. I download poster images from http://www.carteles.metropoliglobal.com/ (great site by the way for movie posters), many of which have a height of 2,500 or 3,000 pixels, and can't see the whole thing because the poster viewer is not resizable. Another possible solution for this problem would be allow linking to an outside viewer.