I was thinking if you post a image or if other webmaster are using images hosted on your site. then Would it be considered a backlink. I see Tinypic and Photobucket Having PR 7 is this cuz of their images on other sites. Or do we have to have a hyperlink for the backlinks.
For me, the image tag shows up as a backlink when viewed within Google Webmasters Tools. Not sure if it counts as an actual backlink or if any juice floats backwards though. I assumed that it does. We went through this a few months back when a "major newssite" used a photo from one of my client's site without permission or an actual backlink or credit link. Just that one image being used cost her like 40 gigs in a weeks time. They never did respond but the link is in her Google Webmasters Tools account.
Yes! Links inside images can actually given more weight by the bots. Plus it's fairly easy to optimize an image. Just make sure the file name is the keyword it relates to and go add more keywords on the alt tags.
If we take example of competing image hosting sites (kind of) then for Google to decide which is better they might use image links, also Google's comprehensive image search indicates that they well assume an image as "content".