MM.BRIGHTNESS%

Read or set the display backlight brightness as a percentage (0-100).

b = MM.BRIGHTNESS%
MM.BRIGHTNESS% = 50

On a Linux framebuffer build (Chromebook ISO) the value comes from the panel backlight under /sys/class/backlight; the real Intel/AMD panel backlight is preferred over the ACPI video shim. Reading returns the current percentage and assigning changes the panel.

On every other build (Raspberry Pi / Circle, Windows, macOS, or a Linux host with no backlight) reading returns 100 and assigning is ignored.

Example:

MM.BRIGHTNESS% = 25
PRINT MM.BRIGHTNESS%

Source: docs/help/mm-brightness-percent.txt inmmcore. On the computer, typeHELP MM.BRIGHTNESS%.