LG Ultrafine 4K 21,5-inch Ambient Light Sensor Support

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LG Ultrafine 4K 21,5-inch Ambient Light Sensor Support

Hi,

LG Ultrafine 4K 21,5-inch monitor has an ambient light sensor (ALS). However, ALS has no function at all! I don't know why it doesn't work but my guess was that the MacOS operating system doesn't support it. I'm using Mojave version 10.14.5 (latest) and this monitor is at least 3 years old so this was really weird.

What makes things crazier is that last month I saw this video from 9to5mac reviewing the lates LG Ultrafine: https://www.youtube.com/watch?v=5akdc_bA2FA&t=2s

At 8:14 the guy shows the sensor automatically adjusting the brightness and it really seems to work.

I searched all the internet and also visited the local Apple store about this issue but nobody seems to know anything about it...

If you know anything, please share it here, if not, please leave a feedback to Apple about the issue.

MacBook Pro 13", macOS 10.14

Posted on Jul 14, 2019 5:12 AM

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Answer 1

Tesserax

Level 10

148,507 points

Jul 19, 2019 2:20 PM in response to Alpini

I do know that the latest Macs provide a True Tone option. Is this what you are talking about?

Ref:

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Answer 2

Jul 20, 2019 2:23 AM in response to Alpini

I'm running Mojave on a 2018 Mac Mini with the new 24" LG UltraFine (the one in the youtube video) and it does show "Automatically adjust brightness” in Displays preference, and the brightness slider does move when I turn off the room lights so it's not MacOS. It doesn't move as much as I expected, though.

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Answer 3

Tesserax

Level 10

148,507 points

Jul 14, 2019 10:05 AM in response to Alpini

The operating system should not have anything to do with the ALS sensor on your LG. This type of sensor comes on an assortment of monitors and HDTVs and, as you can imagine, works with the current ambient lighting conditions ... not with the video input signal.

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Answer 4

Alpini Author

Level 1

18 points

Jul 19, 2019 1:24 PM in response to Tesserax

But it doesn't work for anyone which is kinda (very) strange... I also tested it at the local Apple store and it didn't work there either and the guys had no idea. They didn't even know the sensor exist!

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Answer 5

Alpini Author

Level 1

18 points

Jul 20, 2019 12:47 AM in response to Malcolm J. Rayfield

Hello guys,

My mac’s screen works just fine. Auto brightness enabled (no true tone as my mac is 2016).

But once you connect the display, the monitor screen changes (it shows LG as the main display) and on that screen there is no “automatically adjust brightness” option. This is why I said in my first post that this issue might be about the operating system.

If you search internet, you’ll see this is a very common issue. No ones ALS on first LG displays work! No one. And it seem to be that everyone accepted that. But that 9to5mac video about the latest model (check my first post) makes things even more weird...

Thats what happens if you outsource you monitor business to a subpar brand like LG I guess...

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Answer 6

Alpini Author

Level 1

18 points

Jul 20, 2019 2:48 AM in response to Malcolm J. Rayfield

Do you think it’s a firmware issue? I also updated the firmware of the displays but still nothing...

Is there any way to get some professionals take a look at this? I am surprised how this didn’t become a bigger issue in the community.

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Answer 7

Jul 20, 2019 5:23 AM in response to Alpini

In the youtube video, Displays preference windows are show twice, at 6:20 and 8:16. The first does not show the "Automatically adjust brightness” setting; the second does. Maybe Mirroring was off for the first, and on for the second. Your laptop may be doing the brightness adjustment using its own light sensor,, since you wouldn't want the displays changing independently.

I have a Mac mini, with no light sensor, so it would have to use the display's sensor.

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Answer 8

Alpini Author

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18 points

Jul 20, 2019 7:34 AM in response to Malcolm J. Rayfield

But I use my Macbook Pro in clamshell mode %99 of the time :)) I didn't check if the "Automatically adjust brightness” setting was visible when both screen were on but I'm %90 sure it will not be...

I'm on holiday, will check it when I'm back and let you know...

But... Still... It has to work on clamshell mode too.

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Answer 9

Alpini Author

Level 1

18 points

Aug 2, 2019 7:36 AM in response to Malcolm J. Rayfield

Today I also checked while mirroring the display. There was still no "Automatically adjust brightness” setting under the LG UltraFine preferences window.

Also,

I turned off the lights in my room, the Macbook Display reduced the brightness automatically but there was no change on the LG display.

I will never buy a 3rd party display again... Even if its supported by Apple...

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Answer 10

Jul 19, 2019 7:19 PM in response to Alpini

Do you have "Automatically adjust brightness" enabled in Displays system preference?

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LG Ultrafine 4K 21,5-inch Ambient Light Sensor Support

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