I have tried my best to manually edit files in the AppData\Roaming\Microsoft\Windows\Themes directory but none of the solutions I have found online work. Replacing the transcodedwallpaper file does nothing, Windows will just compress it again. Replacing the cachedimage does nothing, in fact if you fuck with it enough you are rewared with this: http://i.imgur.com/CrPUXhz.jpg
Going through IE or Firefox does not work, going through the control panel does not work.