If your brand perception is key to you and your company then this quick tutorial is the one for you: Creating your Wallpaperįirstly you’ll need an wallpaper image to get started, I designed mine 1920 x 1080 (HD) in Photoshop and saved this into a PNG format. Well this one is purely down to personal preference as an admin and give’s you that “Oh lala” of customisation to make your Macs stand out from the crowd. Hope that solves your problem.You may be thinking, “ Why on earth would I change the login screen wallpaper?” plist files, and this needs an editor that can parse those- easily done with TextMate (or Xcode if in need of 'vanilla'). In some cases, you might need to parse binary. I use it mostly for filtering crap leftovers from tests to keep the defaults tidy- since the background/login is also set there- that's what you need to edit. I wrote a script for the exporting part, it writes each domain into a separate file for easier overview and keeps system namespace/user namespace separate + sorts out system/apple defaults from those that were changed/set by any software the user installed. If you want to do this without any extra software, you would need to edit your defaults by importing/exporting them.

Tinkering with Onyx is quite secure since you can roll back to defaults with one button press, so don't worry about bricking something - but still be aware what you click )

There are also tons of other options you can check out. You can do this by launching Onyx, entering your admin password and choosing the login tab: Onyx is quite a capable utility and it's free - if you like it, donate a bit for the Author though he does a great job with this app. plist's through defaults (tedious), or you can use Onyx for this (simple).

Change background mac login screen