Quick and dirty command line utility to set the brightness of all monitors that support DDC/CI.
There are a few alternatives out there, but they were buggy or didn't meet my immediate needs. e.g. They required you to manually adjust a slider for each monitor, and when running continuously seemed to forget monitors when they, or the machine, went to sleep.
Usage:
SetMonitorBrightness.exe brightness
Per-monitor brightness isn't supported; it tries to set all monitors to the same level. My usage is to create shortcuts and pin them to the Start menu for "Daytime Brightness" and "Nighttime Brightness".