Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
Pixelmator - Pixelmator is an image-editing application for Mac and iPad.
IrfanView - IrfanView ... one of the most popular viewers worldwide.
Pixlr - Pixlr® makes it easy to transform everyday images into stunning works of art.
JPEGView - JPEGView is a small and fast viewer/editor for JPEG, BMP, PNG, GIF and TIFF images.