Change Windows 7 Logon/Login Screen Background
First Goto run and type Regedit and then Enter.
Then Goto the Key
Hkey_local_machine\software\Microsoft\windows\currentVersion\Authentication\logonUI\Background.
Its data, of Boolean type, defines whether or not this behavior is turned on, i.e. 1 for enabled, 0 for disabled. This value may not exist by default, depending on your system. If its not there. Just create it. And give the value 1.
Agin goto Run and type %windir%\system32\oobe\info\backgrounds then enter. If the folder is not there just create it as the path I have given.
The following files (sorted by width-to-height ratio) are supported in this folder:
- backgroundDefault.jpg
- background768x1280.jpg (0.6)
- background900x1440.jpg (0.625)
- background960x1280.jpg (0.75)
- background1024x1280.jpg (0.8)
- background1280x1024.jpg (1.25)
- background1024x768.jpg (1.33-)
- background1280x960.jpg (1.33-)
- background1600x1200.jpg (1.33-)
- background1440x900.jpg (1.6)
- background1920x1200.jpg (1.6)
- background1280x768.jpg (1.66-)
- background1360x768.jpg (1.770833-)
NOTE: Images must be less than 256kb in size.
So copy anyof your favorite wallpaper and put it this folder with name backgroundDefault.jpg
The backgroundDefault.jpg image is loaded and stretched-to-fit when a resolution/ratio-specific background cannot be found. The other resolution/ratio-specific files are self-explanatory. If the background cannot be loaded (e.g. image physically too large, incorrect ratio, etc.), the default SKU-based image is loaded from imagesres.dll. You’ll see a Windows Server-themed grayish background in there, too, suggesting this functionality is not specific to client SKUs.
Thanks to Expert Windows hacker Rafael Rivera for finding out and sharing this.

