Originally Posted by Vladimir Pavic
Gimp 2.8 is not available for 12.04 yet. You can add it by using an external PPA (and not official repositories).
Gimp2.8 is available from the official repositories in Ubuntu 12.10 (will be released October 18th)
I presumed you added an external PPA and tried to install gimp from there cuz i can see newer packages will be installed and dependencies problems.
If you take a look at attached image , you will see
So either you added a PPA manually , or maybe you have proposed updates enabled.
gimp : Depends : libgimp2.0 (<= 2.6.12-z) but 2.7.3-2010072701~ll is to be installed
For PPA you can check software sources "Other software"
and for precise-proposed updates , check if box is marked in the "Update" section.
When you make any change then run in terminal
sudo apt-get update