Why does MacBook Pro keep dining the display?

[donawalt]

Lately, I notice my 2019 MacBook Pro is dimming the display just a little, on its own. I have specifically noted where the slider is on Preferences/Display, and it moves. Automatically Adjust Brightness is off, True Tone is on, Night Shift its on from Sunset to Sunrise, but it happens during the day. It's not on battery so no slightly dimming going on there. Any ideas? Thanks!

 

[velocityg4]

Might be True Tone. When I setup a new Macbook Pro 16 for a client. I noticed colors and brightness looked way off. Disabled true tone and it went to normal. It wasn't just nitpicking. The display just looked really awful. Anyways, True Tone adjusts the display based on background light. How that light hits the sensor will affect it. I'm guessing it was because the Macbook was under a bright fluorescent light that screwed everything up.

 

[donawalt]

Thanks @velocityg4 ! I turned it off. I suspected it might be that. I'll see if I like it with no True Tone, I do like the warmer colors and not the blueish normal hue...

 

[donawalt]

It does seem that True one dims the display a little bit if you watch the slider. What a bummer.

 

[5097842]

I have the same issue with my MBP 16" - the display would have jarring shifts with color temperature (and somewhat with brightness). I just turned it off. Works great on my iPhone and both iPads, not sure what the problem is with the MBP. I retest with every Catalina update, get annoyed that it's not fixed, and then turn it back off.

 

[donawalt]

I just submitted a bug on it - maybe that will help.

 

[jerryk]

It does seem that True one dims the display a little bit if you watch the slider. What a bummer.

It is trying to keep the colors accurate for lighting condition. It measures ambient light and adjust screen brightness and color gamut and white point to match ambient. Dimming the display in certain conditions is necessary, not a bug.

 

[me55]

When you disconnect from the AC adapter and go to battery it dims the display slightly. You can disable that in the Energy Saver preference panel though.

EDIT: Ah crap, didn't see the part about it happening on AC.

 

[donawalt]

It is trying to keep the colors accurate for lighting condition. It measures ambient light and adjust screen brightness and color gamut and white point to match ambient. Dimming the display in certain conditions is necessary, not a bug.

Thanks @jerryk !