How to change LCD intensivity/brightness

Question

How to change brightness of LCD want image look deemed and soft the

xrandr --output LVDS1 --gamma 0.8:0.8:1.1

change only gamma but not the brightness of image. I have no option --brightness for xrandr

Answer 1

From man xrandr (this is not listed in the -h options, but it works for me):

--brightness brightness

Multiply the gamma values on the crtc currently attached to the output to specified floating value. Useful for overly bright or overly dim outputs. However, this is a software only modification, if your hardware has support to actually change the brightness, you will probably prefer to use xbacklight.

I don't know if there is a universal standard for manipulating LCD brightness; if not this will become a matter of hardware drivers, etc.

Which I suspect it is; trying xbacklight -get on my philips LED gave:

»xbacklight -get
No outputs have backlight property

Guess I am stuck using the gimpy buttons on the panel. ;)

BTW: xrandr --brightness does exactly the same thing as using three identical values with --gamma.