Saving and restoring the brightness setting of a display

Question

I have a dual monitor display and I calibrate both displays. My calibrator generates a calibration profile for each monitor, however the brightness is not saved to the profile (apparently this is the same with all calibrators). This means that although I can now switch between profiles with ease, if I change the brightness of a monitor (deliberately or accidentally), I have no way of getting back to the brightness that is correct for the profile.

Is there any way I can save and restore the brightness of each monitor?

Note: When I say brightness I am talking about the Brightness slider found in System Prefs > Displays. The slider offers no clue as to the numeric value of the brightness, so there is no way to return to it.

Answer 1

One approach is to use the open source command line tool, brightness, to set the value on-demand. This way you could find your preferred brightness value and apply that value as needed, or per-profile.

Mac OS X Hints' discussion on Adjust brightness from Terminal covers the tool, how to compile it, and possible scripts to extend its use.

OS X Daily has also covered the tool in Adjust screen brightness from command line.

Answer 2

This just adds a basic how-to to Graham Miln's answer.

1. Download source from here.
2. Open Commandline
3. Run gcc -std=c99 -o brightness brightness.c -framework IOKit -framework ApplicationServices This will create a binary in the same location

To print display(s) brightness:

1. Run /path/to/binary/brightness -l

This will print for example:

display 0: main display, ID 0x42b19a8 display 0: brightness 0.282261 display 1: ID 0x4248e66 display 1: brightness 0.781247

To set display brightness

1. Run /path/to/binary/brightness -d {display index} {display value}

Replace {display index} with the numerical index of the display as shown when printing the brightness value. Replace {display value} with a number between 0 and 1.