Thank you Dirk.
Just wondering if there is an actual difference between a URL and a Permalink? If there is a difference, and an image is just a URL, would it return a 404 if there is no link (internal or external) to any of the pictures?
Moz detected 404's, ScreamingFrog detected the 404's for some (old) pictures on the current site. GWC does not mention anything on 404s on any pictures.