Photos on Samsung Galaxy Note 7 don't fill the whole screen. How do I remove the black lines?

[AC Question]

I've got the new Samsung Galaxy Note 7 and love it. Unfortunately, I was playing around in Gallery viewing some photos and I accidentally did something with the S-pen and now the aspect ratio has changed. When I flipped my phone to landscape, my photos used to fill the whole screen but now and there are annoying black lines other side. If I zoom in it will fill the screen but it's default is now changed.

I've fiddled around for ages in settings trying to change it back. Any help would be gratefully appreciated.

 

[belodion]

Check the Camera settings. You may need to set 16:9.