HuskyPup are you saying that when someone links to one of my photos each time the photo is opened it counts as a visitor?
The problem I had and definitely still occurs for many people is that many social networking sites use a customised Google search box for finding images and when the searcher finds one that they like and is available a hotlink is created between Google images and your site, this in turn generates an AdSense Page Impression if used as a background etc.
Even someone merely searching for an image on those sites can create an AdSense Page Impression. The 200,000 I mention was people just searching for that image that month, just imagine how much bandwidth they would have consumed if they had been able to use it and then every time someone looked at their pages my server would have been hit! And then multiply that by months and months of hotlinking.
If the image is a direct hotlink to your image it will not affect AdSemse and do anything but use up your bandwidth.
Insofar as the picture linking sites are concerned they offer several different methods of linking and some of them will definitely show up in your log as direct referrals from their sites. I have had very little of this happen, even though many of my images are displayed on their sites at the moment, and that was in the couple of days I removed all my protection for testing purposes, therefore I'm not sure whether they create AdSense Page Impressions or not.