How To: Change Login Screen Background And Logo On Ubuntu 11.10
You can use the Simple LightDM Manager to change the background image and the logo from your login screen. You can install the Simple LightDM Manager using the ppa from Claudio Novais for the Simple LightDM Manager.
To install the Simple LightDM Manager open a terminal window (press the SuperKey and type: terminal) and copy+paste the following lines:
sudo apt-add-repository ppa:claudiocn/slm
sudo apt-get update
sudo apt-get install simple-lightdm-manager
To start the Simple LightDM Manager press the SuperKey and type: simple lightdm manager. How it works speaks for itself.. to change the background browse to the location of the image you want to use. And same goes for changing the logo. If you don’t want a logo shown in the login screen then disable it by selecting No Logo. When done click on the Apply changes button and close the Simple LightDM Manager. To see the changes you made all you have to do is logout.