Circle icon on bottom right of image - what is it?

Well, my subject line says it all. I am trying to figure out what the heck the small circle/target icon on the bottom right of some of my images are... I understand when an adjustment is made a "fader/slider" icon is placed on the bottom right, but some of my images have this bulls-eye icon on it. What is this? I have searched the archives and the book that came in the box, but I could not find anything on this.

Please help!