13.04 - Cannot change brightness

23
2014-04
  • Antoine

    I'm using Ubuntu 13.04 and my graphics card is Nvidia GF 620M. For some reason, Ubuntu is using the Ivy Bridge processor. It works fine, though.

    The only issue I'm facing is the brightness. I can't change it. I'm trying to change it through the hot keys in my Acer, but it is not changing. Anyway to do that?

  • Answers
  • SimplySimon

    I have found a cure for this which has worked for me

    • Ubuntu 13.04
    • Packard Bell
      • Intel® Core™ i3-2350M CPU @ 2.30GHz × 4
      • Intel® Sandybridge Mobile
      • 64-bit

    THE ORIGINAL PROBLEM

    The F11 and F12 control the brightness, but although the tooltips showed that the brightness was changing, the screen didn't change.

    enter image description hereenter image description hereenter image description hereenter image description here

    THE CURE

    I cured this by opening and editing the grub menu.

    1. Open Terminal with Ctrl + Alt + T
    2. I typed in sudo gedit /etc/default/grub, entered my password
    3. I changed the line which read GRUB_CMDLINE_LINUX="" to GRUB_CMDLINE_LINUX="acpi_backlight=vendor"
    4. Saved and Closed gedit.
    5. in Terminal I updated the Grub with sudo update-grub
    6. I re-booted the laptop

    Everything is now working.


  • Related Question

    11.04 - How do you change brightness, color and sharpness from command line?
  • YumYumYum

    I am controlling my PC with SSH and scripting. How can i change the brightness, color and sharpness from command line?

    Try 1: failed

    $ sudo redshift -t 5000:5000 -g .5
    Cannot list GNOME panel applets.
    Initialization of gnome-clock failed.
    Trying next provider...
    Latitude and longitude must be set.
    

    Try 2: failed

    $ cat brightness 
    20
    $ cat max_brightness 
    20
    $ echo 1 | sudo tee /sys/class/backlight/acpi_video0/brightness 
    1
    $ echo 20 | sudo tee /sys/class/backlight/acpi_video0/brightness 
    

    Any alternative way to do?

    Follow up: http://jonls.dk/redshift/

    [command]     [1000K to 10000K]       [effects 0.1 to 10.0]
    |       |     /      /                /
    ^       ^     ^      ^                ^
    redshift  -t  1000:1000   -l 0:0  -g .1; Dark
    redshift  -t  1000:1000   -l 0.0  -g  5; Bright
    

  • Related Answers
  • Nimmermehr

    If the driver of your graphics card supports it, then you can use xrandr.

    The following command lists the current configuration:

    xrandr --current --verbose
    

    If you want to change the configuration of an output, then you need the name of the output. This name is part of the output of xrandr --current, for example LVDS1.

    The brightness can be changed like this:

    xrandr --output <outputname> --brightness 0.8
    

    Gamma:

    xrandr --output <outputname> --gamma 0.5:1.0:1.0
    
  • Capt.Nemo

    xrandr will not increase the screen brightness on the hardware level (the one that is changed by the laptop display brightness keys). As the xrandr manual says:

    --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.

    Instead, use xbacklight to change the brightness:

    xbacklight -get #get the current level
    xbacklight -set *percent* #set brightness to a given percentage
    xbacklight -inc *percent* #increase by a given percentage
    xbacklight -dec *percent* #decrease by a given percentage
    

    However, since this is same as using the laptop brightness keys, this cannot go beyond the limits of 0-100%. If you wish to brighten/darken your screen further than that limit, you can use xrandr to force software brightness levels:

    xrandr --output LVDS1 --brightness 0.5
    

    Note that xrandr accepts fractions (0.0-1.0) while xbacklight accepts percentages(0-100)

  • user334639

    For laptops, I just learned from man xrandr:

       --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 modifica‐
              tion, if your  hardware  has  support  to  actually  change  the
              brightness, you will probably prefer to use xbacklight.
    

    So I tried

    xbacklight -get
    xbacklight -set 70
    

    and it works!

  • Sergey

    If you're using redshift, you need to give it your latitude and longitude so it knows when time of day changes. Something like

    redshift -t 5000:5000 -l 55.7:12.6 -g .5 
    

    Though it may be a bit unconventional use of redshift :)

    Also, it works fine without sudo.