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How can I adjust the display color on elementary OS? They only offer predefined profiles that I can set my monitor to, but I can't calibrate any of them. I already have gnome color manager and icc installed.

I want to adjust contrast, red, green, and blue levels, and etc.

EDIT: I figured it out, use xgamma(obsolete see xrandr solution below) command. I didn't realize the magnitude of numbers represents color contrast as well as adjusting color hue.

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You can modify gamma settings (colors and effectively contrast too) using xrandr tool.


First determine the output name of your monitor:

For example:

ravan@ravan:~$ xrandr -q | grep connected
VGA1 connected primary 1366x768+0+0 (normal left inverted right x axis y axis) 410mm x 230mm
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

In the above example I have a monitor connected and seen as output VGA1.


Using xrandr

From man page of xrandr (See man xrandr)

Xrandr is used to set the size, orientation and/or reflection of the outputs for a screen. It can also set the screen size.

command:

xrandr --output [DISPLAY_NAME] --gamma [R_VALUE]:[G_VALUE]:[B_VALUE]

Example:

xrandr --output VGA1 --gamma 1.28:1:1.28 # for purple

In the above example gamma values are in format Red:Green:Blue

See here for corresponding numeric values for RGB colors.

In RGB color table, see decimal code and if you have 128 then use 1.28

EDIT:

If you want to revert then use: 1:1:1 to restore the default state.

EDIT: (tested on freya)

To make changes permanent, add the script to start-up applications.

Open terminal and run:

nano  monitor_display.sh

Add the following lines.

#!/bin/bash
sleep 50
xrandr --output VGA1 --gamma 1.28:1:1.28 #same command you used previously.

Now Ctrl+X --> Y--> ENTER.

Now run:

chmod +x monitor_display.sh

Now to add to startup applications:

Open system settings --> applications --> startup --> click on + and add the command:

/bin/bash monitor_display.sh

Now reboot.

Note: You will see custom command .desktop file in ~/.config/autostart

  • 1
    Also, how do you make the gamma settings permanent? It resets to 1:1:1 after reboot. – Dobob Dec 29 '15 at 16:11
  • I read in the Ubuntu forum that you can save a xorg.conf file in "etc/x11", but I don't have an xorg.conf already so I tried to make one and I didn't have permission. The link: askubuntu.com/questions/63681/… – Dobob Dec 30 '15 at 7:14
  • @Dobob I will add in few minutes. I have to test before post, :) – Ravan Dec 30 '15 at 7:50
  • @Dobob I have edited my answer :) please let me know – Ravan Dec 30 '15 at 8:59
  • It works. I did change "sleep 50" to "sleep 5". The only downside is that "xrandr --verbose -q" returns inaccurate gamma settings. I have set my gamma to "1.0 : 0.93 : 1.0", but xrandr reports "1.0: 1.1: 1.0". Any way to check current gamma settings? It seems that xrandr uses approximated gamma and brightness settings, whereas "xgamma" doesn't. – Dobob Dec 30 '15 at 11:26

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