Backlight adjustment tool similar to xbacklight but with cubic scale. This is intended for backlight devices with large raw adjustment range (0..900, intel_backlight nodes in /sys/class/backlight) and linear brightness response. The tool switches backlight brightness between reasonably small number (20 by default) of positions chosen to compensate for non-linearity in human perception, making the steps between positions visually more or less equal. Not for devices with small ranges like 0..15 (acpi_backlight and such). Use xbacklight with those instead. See the following on why the scale is chosen to be cubic: https://en.wikipedia.org/wiki/Lightness http://warrenmars.com/photography/technical/resolution/human_perception.htm