Prevents users from changing the background image shown when the machine is locked.By default users can change the background image shown when the machine is locked.If you enable this setting the user will not be able to change their lock screen image and they will instead see the default image.
Policy path:
Control Panel\Personalization
Scope:
Machine
Supported on:
At least Windows Server 2012 Windows 8 or Windows RT
Registry settings:
HKLM\Software\Policies\Microsoft\Windows\Personalization!NoChangingLockScreen
Filename:
ControlPanelDisplay.admx