開啟 /usr/share/glib-2.0/schemas/com.canonical.unity-greeter.gschema.xml，並找到「com.canonical.unity-greeter」，將 key「background」改成新的圖片路徑：
<?xml version="1.0" encoding="UTF-8"?>
<schemalist gettext-domain="unity-greeter">
<schema id="com.canonical.unity-greeter" path="/com/canonical/unity-greeter/">
<key name="background" type="s">
<default>'/usr/share/backgrounds/warty-final-ubuntu.png'</default>
<summary>Background file to use, either an image path or a color (e.g. #772953)</summary>
</key>將設定值重新編譯：
cd /usr/share/glib-2.0/schemas/
sudo glib-compile-schemas .