Download photos from book design

Hi please can you tell me how to do the following - I want to check the size (Kb/Mb) & DPI of a photo in my design - can I download just the photo not the page from the design to check? I can't just look in my uploads folder as I have several versions of the same photo ithere (eg. different MB/dpi) and can't recall which one I used. How do I find out please? I thought I would be able to download it direct from the design but all I can download is a page not the pic itself.