xiv is a very simple image viewer without UI and only controled by keys and mouse. A single X11 window or fullscreen and only key shortcuts or mouse controls. Reads PPM, JPEG & TIFF (8 or 16bits) and convert others with ImageMagick.
Very nice image viewer. The best feature is the threaded image loading, which I have been looking for in other programs for a long time. I do have some suggestions, and don't know where to send them, I guess I'll put them here. 1) I would like the escape key to quit as well, it should be as simple as adding another else if (ks==XK_Escape) 2) I prefer previous/next image to be done by the mouse wheel, so I just switched buttons 2,3 with 4,5. It would be nice if it were more configurable without editing source. 3) I would like an option to turn off imagemagick use, because it caches files to disk, which may not be desirable. I added a global variable "bool imagemagick=true;" and an option '-no-imagemagick' that makes it false and check the option when deciding whether to use it. Keep up the great work.