How To Install Ati Video Driver In Ubuntu
I have an ATI Mobility Radeon 4650 HD graphics card.And I have upgrated to Ubuntu 10.04
What drivers should I install for my graphics card?
Ati Video Driver Updates
1 Answer
Install ATI AMD Catalyst drivers in Ubuntu 13.04 Raring/Ubuntu 12.10 Quantal/Ubuntu 12.04 Precise/Linux Mint 14/13/Any Ubuntu based distribu. First,install Envyng which is a simple GUI tool that can be used to install/uninstall Video driver for your ubuntu. Just use one command in.

First, be sure of your graphic card by checking in Terminal.
If the system shows you that None known., you've to use Fglrx Driver.
However, if the system supports the type of graphic system you use, for HD 4xxx / R700 based cardsaccording to you stated, it can easily be installed using System =>Administration =>Hardware Drivers.
Restart xserver by logging out and back in, or typing sudo /etc/init.d/gdm restart.Check status flag
Check functionality by invoking glxgears.

Change overlay type to Xvideo if video upscaling looks blocky.
fore more, you can take a look at Ubuntu Documentations,and this guide