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!
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
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!
IrfanView - IrfanView ... one of the most popular viewers worldwide.
GIMP - GIMP is a multiplatform photo manipulation tool.