I don't know. The only one on the list that I've used is Irfanview. That is free for non-commercial use. I don't see .PPNG on their supported files though. It looks as if Royal Imaging is a scanning service - if I am searching correctly.
If you are trying to open an image created by someone else, you are supposed to be the owner of that image in order to use it on Facer. There are plenty of copyright discussions in this community.