I would like to know how to set threshold brightness that can be adjusted via the brightness keys (F11, F12) in my case.
When I press F11, the brightness is going too minimum that it ends up in black screen (exactly 0 brightness).
For example, in Windows 8.1, decreasing the brightness via F11, even if the indicator shows 0, it isn't actually 0 but some value which is visible.
xbacklight sets the brightness to low, but it needs to start at the system startup which I've done. It is OK. But, what I want is not a brightness at startup, but adjusting of brightness with the keys, so that the minimum brightness which I set shouldn't go to exactly 0 even if the slider shows 0.
See, when the brightness is adjusted with the Power Manager indicator in Xfce, even if the Slider shows 0, the brightness is set to a value that is not exactly 0 but something reasonable. It's value is 0.533618 (which I got using xbacklight). This value I would like to have as threshold.
So, how to set this value as threshold value for brightness.
P.S: I don't want to install any additional software for this.