This is how to set-up your login image / screen.
When you buy a new computer, the wallpaper and login screen are the same. But if you want to change the wallpaper to a picture of your dog or an other desktop wallpaper of you liking, the login image/screen will remain the same. That simply bother my eye, and Im not the only one.

Choose the same picture as your desktop wallpaper , copy it, and change it to “ DefaulteDesktop.jpg”. Drag and drop the picture int to the CoreService

folder. Look at the instruction here : Movie will come soon