Personalize

Login screen background

See [how to change the login screen background on Windows 10](http://www.howtogeek.com/223875/how-to-change-the-login-screen-background-on-windows-10/).

HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\System

Create DWORD DisableLogonBackgroundImage = 1. Delete it or set it to 0 to revert.

This displays a flat colour. To change the colour, use Personalize > Theme colour, or:

rundll32.exe shell32.dll,Control_RunDLL desk.cpl,Advanced,@Advanced