Gnome Tweaks Login Screem
Ubuntu 17.10 switches to Gnome 3 Desktop and GDM display manager. Although there are options to change desktop wallpaper and lock screen background (it's actually screen saver with date & time displayed), the login screen is always purple.
Make Ubuntu login screen look like Mac OS login screen. Customize Ubuntu in few steps. Works flawlessly with Ubuntu 17.10 and later. To download theme: https
GNOME Tweaks is an indispensable tool that I think EVERY Ubuntu user should install, even if they rarely use it. Why? Because the breadth of Ubuntu customisation options that GNOME Tweaks unlocks is exhaustive and, in a few cases, pretty essential too. Greeting you there at the login screen
Torvalds has suggested that the "GNOME Tweak Tool" should be merged into GNOME 3. As of 2015, critical reception has been much more positive. For example, Debian, a Linux distribution that had historically used GNOME 2, switched to Xfce when GNOME 3 was released but readopted GNOME 3 in time for the release of Debian 8 "Jessie".
The Tweaks.com Logon Changer for Windows 10 provides an easy way to customize the default lock screen image. Just hit the Change Default Logon Wallpaper button, select a new image and the free utility does the work behind the scenes.
With only a single user on the system the login screen is nearly identical to the lock screen, except: It has a power button ; It shows "logged in" instead of "locked" The shield wallpaper used seems to be the one of the most recently logged in user ; Tentative Design. System boots into a login screen. After some inactivity, the screen blanks.