Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
XnView MP - XnView is a free software that allows you to view, resize and edit your images. It supports more than 500 different formats!
JPEGView - JPEGView is a small and fast viewer/editor for JPEG, BMP, PNG, GIF and TIFF images.
Corel AfterShot Pro - Say hello to Corel AfterShot Pro 3, the world’s fastest photo workflow tool! Edit your photos up to 4x faster than Lightroom so you can spend more time behind the camera. Download a free 30-day trial today!
Zoner Photo Studio X - Zoner Photo Studio X is a full RAW editor and image organizer software. It features a bit-map editor with layer and mask support, a video editor and a full module dedicated to culling, cataloging and complex metadata management.
GIMP - GIMP is a multiplatform photo manipulation tool.