Lunar controls the same brightness that you can change by using the monitor's physical buttons.
Unlike other software that only simulate a brightness change by adding a black overlay over your screen,
Lunar uses DDC (Display Data Channel)
to send commands like
set brightness to 30% or
switch input to HDMI 2 directly to the monitor.
This keeps the colour rendering closer to reality, consumes less power and minimizes the backlight bleeding effect.
Apple vendored displays get special treatment as Lunar uses an implementation hidden inside macOS Display Services to control them natively. The list of displays include:
The same brightness and volume keys can now control all your external monitors.
Control while pressing brightness keys to adjust external monitors, or
Option if you want to change the contrast.
If the monitor audio output is active, the volume and mute keys will control it without any setup.
When using multiple devices with the same monitor, you can switch to other inputs and adjust the brightness to a preset value with a single key press.
Sync Mode ports the MacBook's adaptive brightness feature to all your external monitors.
Whenever macOS adapts your MacBook display using the built-in Ambient Light Sensor, Lunar will sync that adjustment to all your monitors.
Syncing also works with adjustments made by TouchBar or brightness keys.
Sensor Mode brings adaptive brightness for any Mac device.
If you use a Mac Mini, a MacBook with the lid closed, or even a Hackintosh, Lunar can automatically adapt your monitors' brightness and contrast based on readings from an external ambient light sensor.
The sensor is wireless, can be powered by USB or Lithium-ion battery and can even be used for multiple computers as long as they're in the same network as the sensor.
Not available because of chip shortage
In Location Mode, Lunar will automatically adapt your monitors based on the sun position in the sky.
Location Mode shines in environments with lots of natural light, where the ambient light in the room correlates with the sun elevation.
If you're using a Mac Mini or a MacBook with the lid closed, Location Mode can be a good alternative because Sync Mode is not available without a built-in Ambient Light sensor.
If you still need the monitors to adapt to the light around you, Sensor Mode would be a better choice.
Lunar can work around M1's lack of DDC support using two separate and very different methods.
The works out of the box method.
Lunar can approximate a decrease in brightness by changing the software gamma tables to make the colors look darker.
This doesn't change the hardware brightness as DDC does, so you have to manually set the monitor's brightness and contrast (using the monitor physical buttons) to the highest possible values that look good for your monitor.
This also means that monitor volume and input can't be controlled.
The why do I have to do this? method...
If you want your DDC controls back, Lunar can use a Raspberry Pi with network access for this.
The way this works is by having the Pi connected to a separate HDMI port of your monitor and Lunar relaying the DDC commands through a custom server running on the Pi.
Use your monitor as a really bright LED panel when you're having video calls in your cozy dark room.
If having your face well lit in a video call is more important than screen space, Lunar can help you with a single hotkey.
Control+Command+5 or use the Lunar menu to activate FaceLight and Lunar will increase the active monitor's brightness and contrast to maximum and place a warm-white overlay on top of your screen.
Press the hotkey again to deactivate FaceLight and return to the previous brightness.
Forget about configuring obscure settings. Just set the monitor brightness to what you need and Lunar will learn from that.
All adaptive modes (Sync, Sensor, Location) support an auto-learning algorithm.
When the brightness or contrast of the monitor is not what you would expect it to be, change it to your preferred value, and Lunar will adjust its brightness/contrast curve to better match your own perception of light.