How to Customize the Login Screen Wallpaper of Mac in OS X Yosemite
Customizing the login screen appearance on a Mac is a nice way to add some personal (or corporate) flair to the OS X login experience. How exactly to change the login screen wallpaper has differed continuously in the many versions of Mac OS throughout the years, but with OS X Yosemite, the process of setting a custom wallpaper is perhaps the easiest it has been in quite some time.
Setting a unique login wallpaper this way is easily done and easily undone too. You can change the background image to anything you’d like, so if you have a picture handy that you’d like to use that’s great, otherwise you can look in our wallpapers section for something that suits you.
Back up your Mac with Time Machine before beginning, though this is a minor change you will want to have a fresh backup anyway just in case you somehow mess something up.
Change the Login Screen Background Wallpaper to a Custom Image in OS X Yosemite
For the purpose of this walkthrough, we’re going to use one of the hidden wallpapers in OS X of a Cosmos moon / earth shot. That secret wallpaper selection in OS X offers many great options to use on any Mac, and the files are already in the proper format.
Whatever image you wish to set as the login background must be a PNG file, and it should be at least the size of your screen resolution if not larger.
- Open the image you want to set as the login wallpaper into Preview app of OS X
- Pull down the “File” menu and choose “Save As”, select PNG as the format, and name the file “com.apple.desktop.admin.png” – save it to somewhere like the Desktop for easy access
- Now go to the Finder of OS X, and hit Command+Shift+G, enter the following path in Go To Folder:
- Locate the file named “com.apple.desktop.admin.png”, select it, and hit Command+D to make a copy or drag it somewhere like your user folder and make a copy that way (this will serve as a backup of the default login screen background image – do not skip this)
- Now copy the version of your custom wallpaper named “com.apple.desktop.admin.png” from the Desktop into the /Library/Caches/ folder
- Close the /Library/Caches/ folder and log out of the current user account to see the change
Your newly customized background login screen image will be set and you’ll see it upon the new login screen again, you will see this image when you log a user out, boot into the new login screen, or lock the screen to a login authentication window. You should not need to reboot the Mac to see the difference.
For an added customization bonus, don’t forget you can add a message to the login screen of OS X too, this is a good place to put an ownership note or message, maybe even a phone number or email address to signify who owns the specific Mac.
You’ll probably want to keep a copy of “com.apple.desktop.admin.png” handy unless you’re really thrilled with your newly customized login screen, that’s your choice. To reverse the customization, you’d simply want to move the backed up copy back into the original location in /Library/Caches/, as you can see in the screen shot above the backup for this particular walkthrough is just kept in the same folder.
Set the Custom Login Wallpaper Background with Terminal
If you’re command line savvy, you can achieve the same results with the following, assuming you have a PNG file handy:
Move the original login wallpaper file to serve as a backup:
mv /Library/Caches/com.apple.desktop.admin.png ~/Desktop/backup/
Move the new image into place to set as the new login screen background picture:
mv ImageForLoginWallpaper.png /Library/Caches/com.apple.desktop.admin.png
Log out to see the change as usual.
For Mac users running a prior version of OS X, setting a custom login screen in OS X Mavericks is quite easy too.
This great tip was discovered on LifeHacker, cheers to the find.