Sony XBR-55X900B - Manual (Page 81)

[Normal]
Displays a 4:3 picture that has been horizontally stretched to 16:9, in 4:3
format.
[Full]
Displays a 16:9 picture in its original size.
[Zoom]
Displays a 16:9 picture that has been converted into 4:3 letter box
format, in the correct aspect ratio.
[Captions]
Stretches the picture horizontally, while fitting captions in the screen.
Available Options (4K (4096×2160) Original Source)
[Normal]
Displays a 4K (4096×2160) picture as 16:9 (3840×2160). Bars appear at
the top and bottom of the screen.
[Full]
Displays a horizontally compressed picture to fit a 16:9 (3840×2160)
screen.
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