The default image viewer in Ubuntu Gnome is eog (Eye of Gnome).If you feel eog to be cumbersome,and want a lightweight image viewer instead,you can try Viewnior.
Viewnior is a fast and simple image viewer for GNU/Linux. It only depends on gtk+-2.0.
* Fullscreen & Slideshow
* Rotate, flip, crop, save, delete images
* Animation support
* Browse only selected images
* Navigation window
* Set image as wallpaper (only under GNOME, see INSTALL file)
* Simple interface
* Configurable mouse actions
Viewnior can be installed from PPA,open a terminal window from Applications -> Accessories menu,and run following commands:
sudo add-apt-repository ppa:xsisqox/ppa sudo apt-get update sudo apt-get install viewnior
The Homepage of Viewnior:http://xsisqox.github.com/Viewnior/index.html