Image Roll
Image Roll is a free and open source, simple and fast image viewer with basic image manipulation tools
Koko
Koko is a free and open source image viewer designed for desktop and touch devices
gThumb
gThumb is a free and open source program for viewing and organizing images in Linux
CoreImage
CoreImage is a free and open source, lightweight and easy to use image viewer for Linux
Qimgv
Qimgv – free and open source fast, configurable, easy to use image viewer with optional video support for Linux and Windows
PhotoQt
PhotoQt is a free and open source multiplatform, fast and simple, yet powerful and highly configurable image viewer
Nomacs
Nomacs – free and open source multiple platforms fast image viewer with additional editing functionality
Phototonic
Phototonic – free and open source software for viewing and organizing images with simple editing functions for Linux
qView
qView – free and open source cross-platform full-featured minimalistic image viewer
Gwenview
Gwenview – free and open source software for viewing images with simple editing features