Darktable - darktable is an open source photography workflow application and raw developer.
Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
RawTherapee - RawTherapee is a free RAW converter and digital photo processing software.
ACDSee - ACDSee is an image viewer that uses very little system resources, and it has a small, sleek size that won't take up much space on your system.
DVDVideoSoft Image Convert and Resize - Free Image Convert and Resize is a compact yet powerful program for batch mode image processing.
JPEGView - JPEGView is a small and fast viewer/editor for JPEG, BMP, PNG, GIF and TIFF images.