Thumbnails in a modern library

I want to display images against items in a document library or list within the rows of the list. 

As an example, I created a basic list with two columns - title and thumbnail. The thumbnail column is of type picture. 

When you look at the information on the item, there is a thumbnail image there. 

How do I get this to show up in the list/library itself? 

If I switch back to classic mode, the pictures show up (a bit too big to be called thumbnails, but present). How do I make images display like this in a modern view? 

Thanks for any help.