Xnview

Xnview
A freeware (not open source) image viewer. It is one of the best alternatives to Windows' ACD See or IrfanView. The user interface is Motif-based, making it lightweight & functional but unattractive.
 * Support for all common image formats, including animated .gif files
 * Image browser with thumbnail views
 * Image enhancing (resizing, effects, rotating, etc.)

Xnview homepage Screenshots