How to change your logon screen background

We all hate that terrible blue logon screen in Windows, so today im going to show you how to change it.
Changing the setting in group policy will allow it to persist even when you change your theme, but the Group Policy Editor is only available in Professional/Ultimate editions of Windows. If you have access to the Group Policy Editor, launch "gpedit.msc" from the Start menu. If not, then read further down the article. Navigate to the following section in the Group Policy Editor window: Computer Configuration\Administrative Templates\System\Logon. You'll find a setting named “Always use custom login background.” Double-click it and set it to Enabled.

Setting An Image
Your image file must be less than 256 KB in size. It's also a good idea to use an image file that matches the resolution of your monitor, so it won’t look stretched. Windows looks for the custom logon screen background image in the following directory: C:\Windows\System32\oobe\info\backgrounds.
By default, the info and backgrounds folders don't exist. Navigate to the C:\Windows\System32\oobe folder and create them yourself by right-clicking inside the folder, pointing to New, and selecting New Folder. Copy your desired background image to the backgrounds folder and name it backgroundDefault.jpg.
The change will take effect immediately – no system reboot required. The first time you log out or lock your screen (try the WinKey-L keyboard shortcut), you'll see your new background.

If you don't have access to the Group Policy Editor, then use the following method. Keep in mind that when you change themes, it will revert back to the original image.

Launch the Registry Editor by typing regedit into the search box in the Start menu and pressing Enter.
In the Registry Editor, navigate to the following key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Authentication\LogonUI\Background. You'll see an DWORD value named OEMBackground. If you don't see it, right click in the right pane, point to the New submenu and create a new DWORD value with this name. Double-click the OEMBackground value and set its value to 1. Note that selecting a new theme in the Appearance and Personalization window will upset this registry value. Selecting a theme will change the value of the key to the value stored in the theme's .ini file, which is probably 0 – if you change your theme, you'll have to perform this registry tweak again. Cheers, Sam