Adjust the Display With xgamma and xrandr
xrandr:
The command structure is xrandr --output displayname --brightness brightness where displayname is the connected display that you have chosen from the list that you get with the command xrandr -q | grep " connected"and brightness is a value of your choosing (1 being the default). Values above 2 will wash things out to the point of being virtually unreadable, and values of .1 or below aren't recommended either.
xgamma:
Sadly, some of this page is just copied from the Linux How Do I: A Linux Q&A page for now. Details on these commands will be added in the future.
Contents
Display Resolutions Available for the Monitor
Use the xrandr command. Xrandr is used to set the size, orientation and/or reflection of the outputs for a screen. It can also set the screen size.
If you type 'xrandr' and ENTER you will see info about your current display. See if you are using something like VGA-1, DVI-0, HDMI-1, DP-1, etc etc <- examples only
DO NOT TYPE: xgamma --output VGA-1 --brightness 0 (substitute VGA-1) for your display, this will make your screen black and you will see nothing. Here is a working example:
xrandr --output VGA-1 --brightness 0.75
Learn more
man xrandr
Interesting side note: A Linux Mint system with an analog VGA LCD monitor connected is identified as 'VGA1' on a Mint 18.3 system, and 'VGA-1' on Mint 19.2. Notice the addition of the dash since the update. Which module this comes from and why development is so inconsistent is unknown. To the developers I suggest keeping the same name convention.
VGA1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 531mm x 299mm
Adjusting the Display Contrast, Tint, and Brightness from the Command Line
You can Adjust the Display With xgamma and xrandr from the command line. See xrandr above.
xrandr --output VGA-1 --gamma 1:1:1
Use the xgamma command. A gamma value of 1.0 is the default. A gamma value of 0.8 would give you more contrast. A value of 1.4 would be much less contrast. Example usage:
xgamma -gamma 0.8
xgamma - Alter a monitor's gamma correction through the X server. The gamma correction can either be defined as a single value, or separately for the red, green and blue components. Also: -rgamma -ggamma -bgamma
Learn more
man xgamma
testing
$ xgamma -> Red 0.700, Green 0.700, Blue 0.700 $ xrandr --output VGA-1 --gamma 1.5:1.5:1.5 $ xgamma -> Red 0.700, Green 0.700, Blue 0.700 $ xrandr --output VGA-1 --brightness 0.5 $ xgamma -> Red 0.700, Green 0.700, Blue 0.700 $ xgamma -gamma .9 -> Red 0.700, Green 0.700, Blue 0.700 <- Red 0.900, Green 0.900, Blue 0.900
Restore default
xrandr --output VGA-1 --gamma 1:1:1 --brightness 1.0
eye strain relief
The full brightness setting is:
xrandr --output VGA-1 --gamma 1:1:1 --brightness 1.0
The nighttime setting is:
xrandr --output VGA-1 --gamma 1.1:0.8:0.7 --brightness 0.55
Reading setting:
xrandr --output VGA-1 --gamma 0.9:0.9:0.8 --brightness 0.85
High contrast for gaming:
xrandr --output VGA-1 --gamma 0.9:0.9:0.9 --brightness 1.3
