The majority of modern day PC hardware uses display technology from either Nvidia, ATI/AMD, or Intel.
Intel drivers are open source but the official Nvidia and ATI/AMD drivers are proprietary. Fresh KXStudio installations include official drivers for Intel video but only unofficial drivers for Nvidia and ATI/AMD. The official Nvidia or ATI/AMD drivers are easily added if required, and they often provide superior performance (especially for OpenGL 3D and gaming), extra or more complete features, and better power management.
If you're unsure what vendor or model video hardware you have installed in your machine, open a terminal (such as Konsole) and type:
lspci
lspci will 'List PCI' hardware installed on your machine, including your video device - the make and model of which is listed as being a 'VGA compatible controller'. If it is a Nvidia or ATI/AMD device then you may want to switch to the non-free driver, if its available for your hardware, to take advantage of the extra features and better performance.
The 'Additional Drivers' tool can be used to simplify the process of downloading and installing or removing non-free video drivers. It requires that you are connected to the internet for it to fetch the requested drivers. From the KX Studio desktop menu you can find it under the Applications → System sub-menu or you may find it easier to search for it.
When you run the Additional Drivers tool it will check the type of video hardware you have before presenting a new window in which you will see a list of compatible drivers, if any are available. You may be presented with more than one suitable driver but it's safe to use the recommended version if you're unsure which version of the driver is best for you. Select a driver, then click 'Activate' which will then download and install the new driver. The new driver will not take effect until you have rebooted.
To enable the screen brightness control keys and disable the NVIDIA boot logo on my NVIDIA-using laptop using the non-free nvidia driver I had to create a file located at /usr/share/X11/xorg.conf.d/10-nvidia-brightness.conf containing:
Section "Device" Identifier "Device0" Driver "nvidia" VendorName "NVIDIA Corporation" BoardName "GeForce 8600M" Option "RegistryDwords" "EnableBrightnessControl=1" Option "NoLogo" "true" EndSection
For thorough information about the proprietary AMD drivers, including how to install more up-to-date drivers or how to remove the proprietary drivers and return to the FLOSS ones, see the community wiki: wiki.cchtml.com