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drecc

macrumors regular
Original poster
Nov 6, 2014
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Apple's support document https://support.apple.com/en-us/HT208909 says:

"True Tone can also adjust these external displays when they're connected to your MacBook Pro with its lid open:
Apple Thunderbolt Display, using the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 adapter
LG UltraFine 5K Display
LG UltraFine 4K Display"

However, I just received the 2018 MBP 15" today, and True Tone seems to work on my old LG 31MU97 (a 4K monitor which pre-dates the LG Ultrafine 4K and 5K monitors).

It seems that whatever True Tone color temperature that Apple decides to use on the laptop display is also used on the external monitor.

I'm guessing that True Tone will therefore also work on any other brand of external monitor, although I don't currently have any other monitors to test that theory with.

However, the MBP has no ability to alter the brightness/contrast settings on my external Monitor, since my monitor is not the official Apple Thunderbolt display or one of the special Apple/LG collaboration UltraFine models. I think there is a special thunderbolt-only communication channel which is why only those monitors support brightness adjustment (vs the official DDC/CI signalling standard that Apple don't seem to have implemented support for).

So I'm wondering whether I'm seeing the full True Tone benefits that someone with an UltraFine monitor would see? Or perhaps I'm only getting the color temperature adjustments, but if I had an UltraFine there would be brightness contrast auto-adjustments too?
 
You sure you aren't seeing Night Shift at work?

Yes. I've just tested it again. Night shift is definitely disabled.

Right now, I have the external monitor connected, and my laptop open. If I untick True Tone, I see both my laptop screen and external monitor transition into a cooler color temperature (less warm, more blue). When I tick the box again to enable True Tone, both screens simultaneously get warmer and more orange/yellow. This is the evidence upon which I make the claim that True Tone will work with any external monitor.
 
I currently have my MBP 13" connected to two 1080p Acer monitors at work via USB to DVI adapters and I can confirm that the MBP does in fact adjust them for true tone, at least to an extent. When the MBP is open they get warmer to match the MBP screen, and when I close it they get much whiter. I imagine that TB monitors might also adjust brightness and contrast but we at least get color temp on all monitors it seems ;)
 
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That's great. One of the reasons I got an LG 5K is because of the TrueTone support. I'll have to try my 24" Dell 4K display as well!
 
What would be great is if I could temporarily open the MBP lid and get it to tell me the color temperature that it is calculating is ideal for the external monitor, and then somehow issue a command to tell the external monitor to keep that color temperature even if I close the lid.

I could keep the MBP open, but it takes up too much desk space so I normally have it in a vertical stand.
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One of the reasons I got an LG 5K is because of the TrueTone support

The LG 5K has an ambient light sensor, but is apparently not functional according to this: https://9to5mac.com/2017/01/02/lg-ultrafine-5k-display-faq/

Does True Tone work on your LG 5K if your MBP lid is closed?
 
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It worked on my Dell P2715Q. I was quite surprised actually, but I turned it off since I’m doing video editing and it can cause issues when doing color correction. I love it when not editing though! I have to keep the lid open otherwise the external display will revert to normal.
 
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Yes. I've just tested it again. Night shift is definitely disabled.

Right now, I have the external monitor connected, and my laptop open. If I untick True Tone, I see both my laptop screen and external monitor transition into a cooler color temperature (less warm, more blue). When I tick the box again to enable True Tone, both screens simultaneously get warmer and more orange/yellow. This is the evidence upon which I make the claim that True Tone will work with any external monitor.
You're totally right. Just tried it on mine as well (LG 27UK600) and confirmed it works. That's a nice surprise!
 
That's very cool if it's the case. I have an LG 27" 4K monitor (connected via DisplayPort) with my current MacBook Pro and was disappointed to read that this setup wasn't supported. My 2018 MacBook Pro arrives today (yay!) so fingers crossed, I guess.

Is there a technical reason why Apple only officially support True Tone on the USB-C (Thunderbolt) monitors? Maybe to control things like brightness as well as temp? Seeing as Night Shift works I don't see why True Tone won't either. Any thoughts?
 
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Its not massively surprising is it? Its essentially measuring the light conditions on the macbook pro and adjusting the colour temperature as a result. You could do this manually before on monitors and screens so I can't think of why it would only be available for the LG ultrafines. Apple has a deal with them and is still pushing those monitors so those are just the only ones they wanted to promote.
 
Its not massively surprising is it? Its essentially measuring the light conditions on the macbook pro and adjusting the colour temperature as a result. You could do this manually before on monitors and screens so I can't think of why it would only be available for the LG ultrafines. Apple has a deal with them and is still pushing those monitors so those are just the only ones they wanted to promote.

Exactly. I can't think of a reason other than Apple pushing that super expensive 5K LG display. The only difference between that and LG's other models is that most others connect via DisplayPort or HDMI as opposed to Thunderbolt via the over USB-C.
 
Confirmed that it also seems to work on my 27" 4K (LG 27UD69P) monitor that's connected via DisplayPort. I didn't think it was doing at first but when toggling True Tone on the MacBook I saw the change. :)
 
Is anyone having problems with their docked 2018 MBP waking up from sleep and activating the external monitor?

Every morning, I'm now finding myself having to open the MBP lid, unplug the USB-C->DisplayPort cable, and then re-plug it back in. Only then will the display activate.

I didn't have this problem with the same monitor with my 2013 rMBP which used a thunderbolt2->displayport cable.
 
How long until Apple fixes this bug I wonder...

Why would they. It would have been super easy to limit it to 2 monitors they know very well. People aren't going to drop a few thousand pounds on new monitors to get true tone. Apple are ***** at times but its usually for some vaguely justifiable reason.
 
TrueTone definitely works on my 2 x new LG U2718Q 4K displays plugged directly into an Akitio Node Pro eGPU with AMD Vega 64.
 
What would be great is if I could temporarily open the MBP lid and get it to tell me the color temperature that it is calculating is ideal for the external monitor, and then somehow issue a command to tell the external monitor to keep that color temperature even if I close the lid.

I could keep the MBP open, but it takes up too much desk space so I normally have it in a vertical stand.
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The LG 5K has an ambient light sensor, but is apparently not functional according to this: https://9to5mac.com/2017/01/02/lg-ultrafine-5k-display-faq/

Does True Tone work on your LG 5K if your MBP lid is closed?
did you find any solution for closed lids?
 
No, sorry, I still don't know if this is possible.
looks like not possibe with LG monitor sensors. maybe some developer can find a way get iPhones ambient sensors data in to mac. It would be great solution.
 
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