Where do I find display brightness controls in Lubuntu?

I'm looking for a control to be able to change my standard display brightness in Lubuntu. I've tried How do I set default display brightness? but my system settings does not include a Screen option.

I've also tried Power Manager, Monitor Settings and Screensaver under Preferences and couldn't spot anything to control this option. The function key mappings (this is a laptop) work to change the brightness, but I'm looking for a UI option as the laptop is physically set up to be mouse-based (keyboard is hard to access with how we've got it set up).

Solution 1:

I tried the xrandr --output VGA1 --brightness 0.9 command from Lubuntu running on my netbook(Samsung NC110, Intel Atom N455 1.66Ghz RAM 2GB). This could only produce terminal's retort of “xrandr: Need crtc to set gamma on.”
Afterwards I kept searching on the web and found out about the “xbacklight -inc XX” command, which solved my problem. The XX stands for % you want increased(-inc) or decreased(-dec), so the actual command that I used was xbacklight -dec 40 since my monitor was too bright.

P.S.- I still would like to know how to give others with answers written feedback (other than just clicking on a "Yes" or "No") on this site, as with most of the Linux realm, user friendliness is a luxury rarely found. Currently I only understand how to provide answers.

Solution 2:

Well, after a couple of minutes in Google, I came up with this:

xrandr --output VGA1 --brightness 0.9

The above command tells the xrandr script to "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" (from the xrandr man page).

Change the name of the output to the one you need. I found this useful instead of all the other advice on the internet because I have a multi monitor setup and the laptop keyboard shortcuts only work on the laptop's screen.

Final comment, once you reboot you may have to run this command again. If you don't want to do that, add this to a script and execute that when your system boots.

Solution 3:

run command

 sudo apt-get install xbacklight 

it will install the program, which worked great on my LXDE install on Toshiba Chromebook. xbacklight will give you the % of screen brightness, you can see the list of commands, but xbacklight -dec XX will decrease BY XX percentage, -inc XX increase.