How can I improve the image quality on a 4K TV

Hello,

I’ve recently made the switch to a 4K TV , an LG one, and installed Plex on it. First thing I noticed was that when playing some pictures from the Plex server I’m not getting the resolution I was hoping. Getting closer to the TV it became apparent that the images look pretty horrible in fact and nothing like the original. Is there a setting somewhere that would allow the original image to be played instead of what appears to be a smaller size version of the image which is subsequently stretched to fit the TV’s viewport?

Thanks,
Ionut

It’s the plex client for WebOS 4.7(LG55B7V OLED TV). Don’t ask me the plex client version but it must be the latest one as I’ve just installed it a week ago. Anything in particular I could try to improve the visual appearance?