Why is the colour tone of my screen changing?
I just had a weird experience. I have my work laptop (MacBook Pro, 14-inch, Nov 2024, M4 Pro) plugged in yo my screen (LG HDR WQHD). I realised I was not using the built-in display and closed the lid of the laptop. Then suddenly colours shifted on the LG display. What was going on‽
So I spent a minute staring intensely at the Displays section of System Settings. I clicked the “Night Shift…” button at least 5 times to make sure I was not going crazy:
What is lacking from that view is the actual built-in display. This is because Apple does not let you access its settings unless the display is actually active. Acting as if the display not exist at all otherwise. So I try again with the lid opened, but nothing obvious changes:
🤔 So what if I take a look at the settings for the built-in display?
There is a toggle here that does not exist for the LG. Actually several, but only one that is clearly active: True Tone.
Automatically adapt display to make colours appear consistent in different ambient lighting conditions.
My educated guess would be that this is only available when the lid is open because the ambient light sensor is close to the camera. True Tone not being an option when the lid is closed makes sense.
What does not make sense to me is a toggle that is only present on the display settings for the built-in display affecting the other display! The Brightness slider in the same section does not affect the LG in the slightest. (I use BetterDisplay for that.)
At least I have found the culprit.