How to change the Xorg gamma/brightness

brightnessdisplay-settingsxorg

I'm trying to play a game (Deus Ex) which I have to modify the brightness since it is very dark in my ambiance. The game has a "Brightness" setting, but lately it doesn't work. I tried to figure out how to change it and find out that xgamma do a similar effect with xgamma -gamma 5. But whenever I change it, the settings revert back after almost a second (so yeah, my screen light up then shuts down). How can I either, make the xgamma settings permanent (or persistent) or I have to use another tool?

My system is a desktop.

Seemsly xrandr --output DVI-0 --brightness 2 do the same, but still reverts back to 0 whenever I apply the settings.

Each time I try to change it the following output fill the Xorg.0.log file:

[ 14768.313] (II) RADEON(0): EDID vendor "HWP", prod id 9798
[ 14768.313] (II) RADEON(0): Using hsync ranges from config file
[ 14768.313] (II) RADEON(0): Using vrefresh ranges from config file
[ 14768.313] (II) RADEON(0): Printing DDC gathered Modelines:
[ 14768.313] (II) RADEON(0): Modeline "1024x768"x0.0   65.00  1024 1048 1184 1344  768 771 777 806 -hsync -vsync (48.4 kHz eP)
[ 14768.313] (II) RADEON(0): Modeline "800x600"x0.0   40.00  800 840 968 1056  600 601 605 628 +hsync +vsync (37.9 kHz e)
[ 14768.313] (II) RADEON(0): Modeline "640x480"x0.0   31.50  640 656 720 840  480 481 484 500 -hsync -vsync (37.5 kHz e)
[ 14768.313] (II) RADEON(0): Modeline "640x480"x0.0   31.50  640 664 704 832  480 489 492 520 -hsync -vsync (37.9 kHz e)
[ 14768.313] (II) RADEON(0): Modeline "640x480"x0.0   25.18  640 656 752 800  480 490 492 525 -hsync -vsync (31.5 kHz e)
[ 14768.313] (II) RADEON(0): Modeline "720x400"x0.0   28.32  720 738 846 900  400 412 414 449 -hsync +vsync (31.5 kHz e)
[ 14768.313] (II) RADEON(0): Modeline "1024x768"x0.0   78.75  1024 1040 1136 1312  768 769 772 800 +hsync +vsync (60.0 kHz e)
[ 14768.313] (II) RADEON(0): Modeline "1024x768"x0.0   75.00  1024 1048 1184 1328  768 771 777 806 -hsync -vsync (56.5 kHz e)
[ 14768.313] (II) RADEON(0): Modeline "832x624"x0.0   57.28  832 864 928 1152  624 625 628 667 -hsync -vsync (49.7 kHz e)
[ 14768.313] (II) RADEON(0): Modeline "800x600"x0.0   49.50  800 816 896 1056  600 601 604 625 +hsync +vsync (46.9 kHz e)
[ 14768.313] (II) RADEON(0): Modeline "800x600"x0.0   50.00  800 856 976 1040  600 637 643 666 +hsync +vsync (48.1 kHz e)

So, apparently my monitor gets redetected each time.

Best Answer

Silly me! I have xflux with fluxgui activated, each time I would like to modify the settings xflux will be in my way. All commands worked, just that xflux would revert it back.

Those who want to change their gamma/brightness:

Use xrandr to list your outputs:

$ xrandr
Screen 0: minimum 320 x 200, current 1024 x 768, maximum 8192 x 8192
DVI-0 connected 1024x768+0+0 (normal left inverted right x axis y axis) 304mm x 228mm

As you can see my output is DVI-0 to change the brightness:

xrandr --output DVI-0 --brightness 2

To change the gamma:

xrandr --output DVI-0 --gamma 2:2:1

Related Solutions

Linux – How to use command line to change brightness and color

You can modify gamma settings (colors and effectively contrast too) using xrandr tool. First determine the output name of your monitor:

 $ xrandr -q | grep connected
 DFP1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 477mm x 268mm
 CRT1 disconnected (normal left inverted right x axis y axis)

In the above example I have a monitor connected and seen as output DFP1. So now for the gamma modification example:

$ xrandr --output DFP1 --gamma 0.8:0.8:1.1

Where gamma values are in format Red:Green:Blue.

Edit: Another option is xcalib (you may need to install it first). It can be used with -a parameter to have effect directly on the connected monitor. See the output of xcalib for more details. Unfortunately, the color/brightness settings seem to work additively, so you might need to do randr --output ... --gamma 1:1:1 to restore the default state.

XRandR – How to Change LCD Brightness

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.

Best Answer

Those who want to change their gamma/brightness:

Related Solutions

Linux – How to use command line to change brightness and color

XRandR – How to Change LCD Brightness

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