Samsung PN51E6500EFXZA - Manual (Page 630)

HD channels will have black bars
on either side of the screen when
displaying upscaled SD (4:3) contents.
Black bars will appear on the top and
bottom of the screen when you watch
movies that have aspect ratios different
from your TV.
Adjust the picture size options on your
external device or the TV to full screen.
A Mode Not Supported message appears.
Check the supported resolution of the