rundll32.exe "C:\Program Files\Windows Photo Viewer\PhotoViewer.dll", ImageView_Fullscreen [PathToImage] rundll32.exe : The system tool used to run DLL files.
%ProgramFiles%\Windows Photo Viewer\PhotoViewer.dll windows photo viewer path
C:\Program Files\Windows Photo Viewer\PhotoViewer.dll rundll32
%ProgramFiles%\Windows Photo Gallery\PhotoGallery.exe windows photo viewer path
In newer versions of Windows, Microsoft has hidden the classic Photo Viewer in favor of the modern app. While the .dll file usually remains on your hard drive, it is often disabled in the Registry, meaning it won't appear in the "Open with" menu.
Alternatively, if you're looking to set Windows Photo Viewer as the default image viewer: