Monarch Graphic Files are files which cannot be edited in any other application and using an image viewer will not give the results you want. Based on my experience I know that XnView is an image viewer with great capabilities and great image viewing support. Download the software from our website and install it using the wizard incorporated into the setup package and start it from your desktop. Then go to
Main Menu > Tools > Options > Associations> Click Add all or press
F12 > Associations > Add All. Then click on your file and try to open it. If it's still not recognized, right click it > Open With > Xnview. This applies to only viewing images.I've searched for different plug-ins able to import MGF files and couldn't find any.