How do I change the login background for Mavericks?

Then give Mavericks a favorite login background! In fact, it is not difficult, you only need to make (or find) the appropriate size of the background map, replace the Mavericks system in the relevant resource files.

The only thing to be aware of is that if you want to get the best results, you need to prepare a picture of your screen resolution (click here) with a 8095 ratio, and a 160190 percentage of the picture to replace it to achieve full screen replacement effect. For example, your MAC screen resolution is 1280800, then you need to prepare a 12801520-resolution background picture (1280/80=16,1695=1520) and a 25603040-resolution picture, and all need to be saved in PNG format.

Copy each of the two images and get 4 pictures. The two small resolution pictures are named Apple.png and Apple_s1.png, and two large resolution images are named Apple@2x.png and Apple_s1@2x.png respectively.

Then press the shortcut key command+shift+g in the Finder to enter the following path:

/system/library/privateframeworks/loginuikit.framework/versions/a/frameworks/loginuicore.framework/resources/

Locate the Apple.png, Apple_s1.png, Apple@2x.png, apple_s1@2x.png four pictures in the folder, back them up to a safe location, and replace them with the 4 pictures that you got before (you need to enter an Administrator password Authentication).

After you log off the current account, you can see in the login interface that the new background is in effect.