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!
Portrait Professional - PortraitPro is the world’s best-selling retouching software. Fast and intuitive, PortraitPro edits your portrait photos for beautiful results
IrfanView - IrfanView ... one of the most popular viewers worldwide.
Microsoft Selfie - A selfie and portrait enhancement app
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
PT Portrait - Easy portrait editing software. Remove blemishes. Thin wrinkles & perfect skin.
JPEGView - JPEGView is a small and fast viewer/editor for JPEG, BMP, PNG, GIF and TIFF images.