I have noticed that non-square album images (transparent PNG images) show fine in the album view and the artist page - but in the now playing view, it seems that the image is placed on a black square background and so for any non-square image, black bars are seen along the long sides.
See attached screenshot. Hopefully this can be fixed.
Thanks @anon47919701 - if I am understanding you correctly, you fixed the issue by changing all the thumbs to .png? Or did I misinterpret?
That’s no real fix, more like experimental prove that Roon could provide transparency in thumbs, technically. Also, this has no influence on placeholder backgrounds, obviously. This would show through the transparent image areas … 
