Change the Login Screen Wallpaper in OS X Mavericks
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.