XnView MP stands for Multi Platform = it is available for Windows, Linux and MacOS. It is a continuation of the older XnView Classic. In my opinion it is a great alternative to Windows photos app or any Linux image viewer that comes preinstalled. I even think it is an alternative to IrfanView. It is really fast and simple to use, supports more than 500 image formats, has built in folder browser, image converter, editor... AND MORE!
IrfanView - IrfanView ... one of the most popular viewers worldwide.
Topaz DeNoise - Topaz DeNoise is a new and highly effective way to remove digital image noise.
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
Neat Image - Neat Image reduces high ISO noise, grain, artifacts in images from digital cameras, flatbed and slide scanners. It is a tool for professional photographers and digital image processing enthusiasts.
JPEGView - JPEGView is a small and fast viewer/editor for JPEG, BMP, PNG, GIF and TIFF images.
Noise Ninja - Photo Ninja is a professional-grade raw converter that delivers exceptional image quality with a distinctive, natural look.