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macrumors 6502
Original poster
Dec 2, 2018
From LG documenation:

“If you connect a device that supports HDMI ULTRA HD Deep Color, you can enjoy a clearer image. After connecting the playback device, set HDMI ULTRA HD Deep Color to On. If the connected device does not support this function, it may not work properly. In that case, change the TV’s HDMI ULTRA HD Deep Color setting to Off.”

Supported Display Resolution
  • On : Supports 4K@120 Hz (4:4:4, 4:2:2, and 4:2:0)
  • Off : Supports 4K@60 Hz (4:2:0)

I would assume that the Apple TV 4K supports this feature, but I’m not 100% sure.


macrumors demi-god
Apr 17, 2017
Cupertino, CA
Apple TV supports up to 4K 60-fps chroma 4:4:4. I assume it does for 4:4:4.

I would turn it on the TV and set your Apple TV to chroma 4.4.4 then check the difference between it off and on. Just make sure you have the right HDMI cable either premium or ultra speed.
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macrumors newbie
Jul 19, 2019
Indirectly related to this: try using "RGB High" on the ATV, instead of using the YCbCr format with 4:4:4 chroma subsampling. I think that you'll like better, the picture.
Also, ATV does not yet support Fixed Rate Link (FRL). That means that 4K@120 Hz (4:4:4) on the ATV is not currently possible.
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