On the whole, a Mac doesn’t management the brightness of an exterior monitor as such.
The reasons concerning min/max values in GPU kernel extensions and PWM signaling to LCD drivers chips are incorrect. That form of factor applies solely to the inner show on the laptop computer.
In your case, you may have an exterior monitor linked over HDMI. There isn’t any PWM brightness sign in a HDMI connector – it merely does not work that approach.
Just some screens truly help controlling their brightness from the pc – and once more in some circumstances it is a proprietary interface. On the whole, exterior screens that do help brightness management over HDMI, achieve this by way of DDC.
DDC is an I2C bus with a considerably standardised, digital protocol on high that enables for data to movement to/from the monitor and the pc. The brightness “sign” is thus not analog voltages or a PWM sign, it is digital instructions.
On high of DDC, there’s a regular set of instructions often called MCCS (Monitor Management Command Set). A couple of screens additionally make MCCS out there over USB (for instance the previous Apple Cinema HD show).
MacOS doesn’t ship out these MCCS instructions over DDC to exterior screens. Apple has their very own system for managing brightness on their very own exterior screens, however it’s not used with third-party exterior screens.
To sum that half up – macOS isn’t asking the monitor to decrease its brightness.
Which means there are two potentialities:
Both:
- The settings within the on-screen-display menu on the monitor has the brightness by some means set decrease than most (unlikely given the data you may have included in your reply)
or
- The Mac isn’t sending the identical picture information to the monitor to show because the Home windows PC.
The latter can occur due to shade profiles:
On the Mac, verify System Settings > Shows and “Color Profile”. Attempt altering that to see if it adjustments the brightness output, you are measuring. Browsers can and can use color profiles – so even if you happen to show the identical PNG file (for instance) in two totally different browsers they will present totally different colors – even when the color code is listed as #FFFFFF for instance. The browser may apply a shade profile as can the working system usually.
If you wish to strive setting the monitor brightness from macOS, you are able to do that by putting in a 3rd social gathering DDC utility. I believe the perfect/best is to put in BetterDisplay or MonitorControl.
It is also for instance the ddcctl software out there from HomeBrew, nonetheless I am undecided how properly it helps your M1-based Mac but.
For the M1 particularly there’s one other software named m1ddc. Sadly it’s not clear whether or not that works when controlling a monitor linked over HDMI. So that you may want to make use of a distinct cable to attach the monitor over DisplayPort as a substitute.