Want to customize the login background of your Mac? Maybe you want to brand it with your company wallpaper or have it match the wallpaper that the user sees when they log in. Well, Apple has made this really simple to do in Yosemite with a single file change.
I’ve made an utility that can be installed on machines to point them to a specific image saved on a web accessible method to set them all to that same image on the login window. This is still a work in progress, so be careful which machines you install it on. https://github.com/Nesteph/LW-Changer