In Windows 10 LTSB 2016 Windows Photo Viewer is only associated with .tif and .tiff files and is not available in the Open with menu.
I added a custom registry entry to the Horizon Agent All Users (including admins) v5 GPO to add Windows Photo Viewer back to the Open with menu.
If you right click on an image file you can go to Open with and select Choose another app (if you select Windows Photo Viewer here, you will not be able to set it as the default).
On the How do you want to open this file screen select Windows Photo Viewer and then check the box to Always use this app to open .PNG files (or .JPG, .JPEG. etc).