by Changing the login screens background wallpaper is a great way to customize the appearance of a Mac. The process of doing so seems to change with every release of OS X though, and that’s no different with swapping out the login wallpaper in OS X Mavericks. Changed yet again with OS X 10.9, you will find that rather than replacing a single file with a new image, you’ll have to replace four separate files to gain a similar customization of the login window, which is seen both upon system boot and with swapping logins with Fast User Switching.
The walkthrough outlined below will replace the boring OS X Mavericks grey login screen background wallpaper with any image of your choice. But there is a catch: doing this will remove the Apple logo you see at the login screen, because what you’re really doing is replacing that Apple logo image with a larger picture that becomes the wallpaper.
Please review the full instructions before beginning this process. If any of this seems too complex or complicated, you’re probably better off waiting for a simpler solution or a third party tool that automates the process. We’re working on finding an easier solution, but in the meantime this works if you don’t mind sacrificing the Apple logo you see at the login screen.
Requirements:
Some patience, familiarity with Finder and modifying basic system files
A large image converted to PNG format that is the resolution of your screen or greater. Need a fancy image? Check out our wallpaper archives
No issue with losing the Apple logo at the login screen to be replaced with your custom image
Comfortable with that? Don’t mind losing that Apple logo above the user names at the authentication screen? Then you’re OK to proceed. You should probably back up your Mac real quick with Time Machine before beginning too, just in case you somehow wreak unintended havoc and replace or delete something outside the scope of this walkthrough. As usual, proceed at your own risk.
Changing the Login Screen Background Wallpaper in OS X Mavericks
Find the image you want to use as the new login screen wallpaper, open it with Preview, and convert it to a PNG file by using “Save As” or “Export As” – the file must be a PNG document
Return to the OS X Finder and make 4 (yes, four) copies of the PNG file, rename the files exactly to be the following: apple.png apple_s1.png apple_s1@2x.png apple@2x.png
Create a new folder somewhere in the Finder (Desktop is good) named “loginscreenbackups” or something similar – if you don’t do this you will not be able to return to the default grey wallpaper
Hit Command+Shift+G and go to the following lengthy directory path:
/System/Library/PrivateFrameworks/LoginUIKit.framework/Versions/A/Frameworks/LoginUICore.framework/Resources/
(Split in two parts, that directory path is: /System/Library/PrivateFrameworks/LoginUIKit.framework/ followed by Versions/A/Frameworks/LoginUICore.framework/Resources/)
Locate the files named “apple_s1.png”, “apple_s1@2x.png”, “apple.png”, and “apple@2x.png” and make a copy of these files in the previously created “loginscreenbackups” folder on the Desktop – you can do this by holding down OPTION while dragging the files
Now drag and drop the four PNG files you created and named in step 2 into this Resources folder, replacing the existing files
Confirm that you want to replace the images, you will need to authenticate with an admin password to confirm the file replacement
The new images will now be in the Resources folder, visible as thumbnails, you’re just about done so close this window:
To see the new login screen wallpaper, log out normally, summon the lock screen, or use Fast User Switching to bring about the changed imagery
In this walkthrough example we used a galaxy image as the replacement login wallpaper, which looks nice and fancy:
Update: By request, here is the galaxy wallpaper used in our walkthrough:
Separately, and a much easier process, you can add a login screen message to this screen if desired. This is a good place to put a friendly message, or to put ownership details of the computer, like a phone number, name, and email address.
There may end up being a simpler way to do this, either through a single file replacement or a third party utility, but in the meantime this method has been confirmed to work with OS X Mavericks (10.9). Remember, the utilities and tricks that worked with changing login background images in prior versions of OS X, from Snow Leopard to the linen images within Lion and Mountain Lion, no longer have any effect. On the other hand, the method outlined above will carry back to Lion and Mountain Lion because they are replacing the Apple logo rather than the linen image.
