Here is a guide to install Gimp 2.8 RC1 on Ubuntu 12.04. GIMP (GNU Image Manipulation Program) is a free and open source software image retouching and editing tool and is freely available in versions tailored for most popular operating systems including Microsoft Windows, Apple Mac OS X, and Linux.
GIMP has tools used for image retouching and editing, free-form drawing, resizing, cropping, photo-montages (combining multiple images), converting between different image formats, and more specialised tasks. Animated images such as GIF and MPEG files can be created using an animation plugin.
To add the PPA and install Gimp 2.8 open a terminal window (press Ctrl+Alt+T) and copy+paste the following lines:
sudo add-apt-repository ppa:otto-kesselgulasch/gimp
sudo apt-get update
sudo apt-get install gimp
When Gimp 2.8 is installed you can close the terminal window. To start Gimp press the SuperKey and type: gimp.