To customize background image scaling create a resource like this:
<?xml version="1.0" encoding="utf-8"?>
<bitmap xmlns:android="http://schemas.android.com/apk/res/android"
android:gravity="center"
android:src="https://stackoverflow.com/questions/1400782/@drawable/list_bkgnd" />
Then it will be centered in the view if used as background. There are also other flags: http://developer.android.com/guide/topics/resources/drawable-resource.html