You can display a Custom Picture before the Login Screen appears.To do
so make sure you have your custom screen saved (.bmp) and ready to go.
Navigate to :
- HKEY_USERS\.DEFAULT\Control Panel\Desktop\
Note:I have set the same on my PC under CURRENT_USER :
- HKEY_CURRENT_USER\Control Panel\Desktop\
Locate here in the right pane the entries :
Wallpaper
(Doubleclick it,enter full path of your Bitmapimage (.bmp) you want to use.)
TileWallpaper
(If you want to tile the picture doubleclick it and set it's value to 1for tile,
0 will not tile the image)
WallpaperStyle
(Doubleclick it to change the style,enter 0 to keep the style
normal,2 will stretch the image to fit the screen)

You can also set the coordinates where the image should appear on the screen,
without stretch or tile.To do so you need to create in the right pane 2 new
entries named as below (right click , new , SZ_REG [String Value]) :
WallpaperOriginX
WallpaperOriginY
Doubleclick the new entries and set their value to the pixel size you want
to have them displayed counted away from the left side (X) and the top (Y).
Reboot your PC to see it work.