Screen brightness too low on PC

Support & Help Requests
#1

CPU - AMD fx-6300
Mobo - Asus M5A78L/USB3
GPU - GTX 580
Monitor - LCD t.v
RAM - 12GB

I’m running MATE 16.04 and the screen brightness is quite low. For general use it’s not an issue but when watching movies the screen is almost black for any scenes shot in low light. Booting into Windows ( separate hdd) the screen is noticable brighter.

I’ve tried installing xbacklight as well as amending a line in Grub to:

GRUB_CMDLINE_LINUX=“acpi_osi= acpi_backlight=vendor”

but neither has had an effect. I ran sudo update-grub and rebooted after making the changes.
I haven’t been able to find a solution online, however must similar cases seem to involve Grub, so here is a full print out:

 >  GRUB_DEFAULT=0
> #GRUB_HIDDEN_TIMEOUT=0
> GRUB_HIDDEN_TIMEOUT_QUIET=true
> GRUB_TIMEOUT=10
> GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
> GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
> GRUB_CMDLINE_LINUX=""

I’ve had the issue for a while but chalked it up to having an old t.v. It wasn’t until I tried out Win7 on a whim that I noticed the difference. Pretty sure this rules out hardware as the culprit for low brightness.

#2

How to increase screen brightness using xrandr

Open a terminal and run the following command:

xrandr -q | grep " connected"

This should give you a output similar to the one below:

eDP1 connected primary 1366x768+0+0 (normal left inverted right x axis y axis) 344mm x 193mm

In the example above, eDP1 is the name of the connected display. Your display may be named differently, but you will need the display name to adjust the screen brightness with xrandr.

Now that I have determined that my display is named eDP1, I would run the following command in a terminal to adjust the display brightness:

xrandr --output eDP1 --brightness 1.1

You can increase or decrease brightness by changing 1.1 in the above command to a different value. For example, 1.5 would increase brightness and 0.9 would decrease brightness.

Once you find the value that works best with your display you can add the command to your Startup Programs list. This way your display brightness will be increased each time you login.

Screenshot at 2018-02-06 20:36:09.png708×515 77.4 KB

You may also consider adjusting the gamma of your display if increasing the brightness makes your display look washed out.

How to change screen gamma using xgamma

Open a terminal and run the following command:

xgamma -help

This will show you the following options:

usage: xgamma [-options]

where the available options are:
-display host:dpy or -d
-quiet or -q
-screen or -s
-version or -v
-gamma f.f Gamma Value
-rgamma f.f Red Gamma Value
-ggamma f.f Green Gamma Value
-bgamma f.f Blue Gamma Value

If no gamma is specified, returns the current setting

As you can see in the example above, you can change the display gamma as a whole by using the -gamma f.f option.

For example:

xgamma -gamma 0.80

Or if you need to, or just want to experiment:

xgamma -rgamma f.f will adjust the Red Gamma Value
xgamma -ggamma f.f will adjust the Green Gamma Value
xgamma -bgamma f.f will adjust the Blue Gamma Value

Again, once you find the value that works best with your display you can add the command to your Startup Programs list, so your display gamma will be adjusted each time you login.

4 Likes
Increasing contrast
#3

Thanks, Steven.
That worked great, the screen has a new lease of life.

Problem solved

1 Like
#4

Steven,

I don’t have any problem with screen brightness or such - I just want to say that your screen brightness adjustment how-to was really quite well done. I have written a lot of how-tos over the years, and my goal is to come up with something as clear and inclusive as what you did here. I have cut/pasted your post into a file and put it in my linux_tips directory. I am sure it will come in handy some day… thanks!

2 Likes
#5

I fully agree. Steven’s guide was was incredibly easy to follow. The section on saving the changed settings as a start up program was also very considerate, and will almost certainly prove to be a useful tool in the future.

Thanks, again.

1 Like
#6

Thank you both for the kind words. I’m so glad this solution worked for you @Huxley.

#7

Steven,

thanks for your reply. I’m no expert and on trying “xrandr -q | grep " connected”" I got

LVDS-1 connected primary 1280x800+0+0 (normal left inverted right x axis y axis) 0mm x 0mm

Double Dutch to me. Do you think there anything I could do to increase brightness/contrast?

Best

#8

There is also xgamma-gui

#9

@lostados in your output LVDS-1 is the name of your connected primary display.

so try entering the following in a terminal

xrandr --output LVDS-1 --brightness 1.1

You can increase or decrease brightness by changing 1.1 in the above command to a different value. For example, 1.5 would increase brightness and 0.9 would decrease brightness.

Once you find the value that works best on your system, you can add the command as a startup program (as seen in my original reply), so that every time you log in to your desktop, the command to adjust your brightness will run on it’s own.

To adjust contrast, try entering the following in a terminal

xgamma -gamma 0.80

Changing 0.80 to a value that works best for your system. Again you can add the command as a startup program, so that every time you log in to your desktop, the command to adjust your contrast will run on it’s own.

#10

Hi Huxley and all,

I'm running dual boot (Windows 8 and Mate). I had this problem also: screen very dim. I simply restarted into Windows OS then maxed out my brightness. Logged back into Mate and now I have full brightness as well.