NeonView is a minimalist, lightweight image viewer written in C and GTK. The goal of NeonView is to stay lightweight while also providing ease of use and only the necessary options a basic image viewer should have. NeonView supports all the popular image formats including JPG, PNG, SVG, GIF or TGA (basically all the formats supported by gdk_pixbuf).

Operating systems: Linux
Screen libraries: GTK+

Probably builds on other operating systems that support GTK+ besides Linux. It builds on Windows with some patches.