Backgroundimage Saver is a quite simple extension that provides help for an annoying technique that can be found on more and more pages. That is to hide images behind a transparent gif to protect them against being saved.
Originally I designed this for print.google.com and www.imdb.com
But unfortunally these example pages did change their protection (at least on some pages) and are now using different layers that lay over each other, so that this plugin does not provide any help here anymore.
So at the moment will not provide any external example pages, although this mechanism is probably still used on quite a few pages.
Here the explanation how it works: Because since these pages place a transparent gif on top of the real graphic you can't just right-click an image and select "Save Image As..." because then you would just save the transparent gif (which is probably not what you want ;-)).
So this simple extension just adds a 'Save Background Image' option to the right click context menu which does the trick.
Furthermore it is helpful if you want to be able to directly save the backgroundimage, since Firefox does not offer this option by default.