DebugPoint published a tutorial about how to change the lock and login screen wallpaper in elementary OS.
How to Change Lock and Login Screen Wallpaper in elementary OS
This tutorial explains the steps you need to change lock and login screen background in elementary OS. This will replace the default grey background. Changing the lock or login screen background grey default wallpaper in elementary OS is a bit difficult.
How to Change Lock and Login Screen Wallpaper in elementary OS
