XnView Software

Thank you, Marsh! And such a quick and helpful reply...

A subset of formats found on web page are enabled by default. There is an option for more.
Does XnView support graphic format .xyz?
Putting advice in 'format cannot be determined' dialog.
It was the second link about going to "Options ...

This is my first post and I want to wholeheartedly thank you for the incredible work you do and the generous support you show people by providing this excellent program for free for non-commercial use.

I have an ancient set of MacPaint image files from the brilliant and no longer published Comic ...