As of Confluence 7.13.0, you can upload a new and completely different version of an image, and it will not change the page history: if you are working on a page named Foo and it is currently at version 2, and you upload a newer version of an image,
This is a serious bug. It means that the items in the page history are not immutable, and they can change image content, without any way to go back and audit and see exactly what the page looked like as of a particular point in time.
Please reopen CONFSERVER-22874, which was identified in 2011 but dismissed as "Not a bug".