Download Logon Controller software from murgee.com/logon-controller/ and install it on your computer. This software will allow you to change your Windows 7 and Windows 8 Logon Wallpaper. You can easily set a custom wallpaper background for your computer Log in screen in Windows 7 and Windows 8.
After you finish installing the software, just run the software Logon Controller. And just set the custom wallpaper which you want to change. You can also restore the Logon Wallpaper to default in this application.