Packhorse Bridge Ghost, Caergwrle, UK

Do you think this is a full-bodied apparition? It's been written that this is one of the best one's out there.  But this can be done with photoshop.
Here's a loaded question I'm going to throw out to all you paranormal investigators. Why is it that an apparition can "change" from white to dark? Or, just white or dark?  Never really could understand that?  In my lifetime I mainly seen dark shadows to a clear "color" semi apparitions. But it still basically, dark.
This picture was taken by the Cheshire Paranormal Society. They believe it's the ghost of Squire Youge a person very known to the area a couple of hundred years ago.