Finding the is different from finding most programs because it does not have a standard .exe file. Instead, it runs as a dynamic link library (DLL) called by the Windows rundll32.exe utility. The Windows Photo Viewer File Path
rundll32 "%ProgramFiles%\Windows NT\Accessories\ImageViewer.dll", ImageView_Fullscreen %1 windows photo viewer path
%ProgramFiles%\Windows Photo Viewer\PhotoViewer.dll Finding the is different from finding most programs
C:\Program Files\Windows Photo Viewer\PhotoViewer.dll windows photo viewer path