Android: Extract the current wallpaper

Note: Root access required

For Android 4.0 and below:
/data/data/com.android.settings/files/wallpaper

For Android 4.1 and above:
/data/system/users/0/wallpaper

To pull the wallpaper with adb:
1. adb root
2. adb pull <path-to-wallpaper>
3. rename the file and append file extension .png or .jpg


Ref:
How to extract default/current wallpaper from an Android Device; Root required - Droidiser