General Support: Add a Save as text/button on Lightbox/plogger

Hi guys. i was thinking of adding something like Save As under the picture in Plogger lightbox theme. So people can save the picture, as it is not possible to right click the picture and save it from there. Now visitors need to right click on picture, and press open in new window/tab to be able to get save the picture from there. Do you understand what im looking for? So anyone have any ideas howto do this. Its easy to add the text and so, but how do i make it save the picture, and how to find out the "real" link to the picture.

Hope you understand what i mean :)