How to adjust display colors in elementary OS

Question

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.

Answer 1

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

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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.

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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

Answer 2

Try DisplayCal https://displaycal.net/

You can both calibrate, and assign profiles to a display. Download the package, install with a package manager (e.g. Eddy) and then run DisplayCal app. To assign a profile, go to File >> Install display device profile

You can also calibrate using that tool too if you have a compatible colorimeter (it supports many third party ones).