By tweaking the Windows Registry, you can change the logon screen.
To Open Registry: Press
windows +r & type
regedit & press
Open the Registry Editor.
In left pane of Registry Editor, go to
OEMBackground DWORD key and Set value of the key to 1.
Select a background image for logon screen with size less than 256 KB and rename that
Copy that image, Open
My Computer and go to
Paste it and select
Copy and Replace.
Tips: Cut and paste the original log-on Screen image in a folder for further use.
Reboot, and now your logon image would have changed.
Note: Modifying the registry can cause serious problems that may require you to reinstall your operating system. I cannot guarantee that problems resulting from modifications to the registry can be solved.