I am using Ubuntu 18.04. My graphics card is AMD Radeon R3 Graphics.

This a screenshot of my screen.

enter image description here

Clearly the blue circle appears purple. Why is it happening and how to solve it?

My system is thoroughly updated and upgraded.

Or is it that I am actually color blind?

  • 1
    Does this blue color test page look blue or purple on your laptop screen? – Chai T. Rex Aug 8 '18 at 17:47
  • It looks purple – Sonevol Aug 8 '18 at 17:47
  • 3
    Is the Night Light mode turned on in Settings > Devices > Display? If so, does turning it off fix it? – HattinGokbori87 Aug 8 '18 at 18:15
  • Yes night mode is turned on, checking it turning off. – Sonevol Aug 8 '18 at 18:22
  • 3
    Wait... you posted a screen shot to show us the color of your screen? This is the one time you are allowed to use a camera to take a picture of your screen, screenshots are going to be rendered by our computers as completely normal. – Sam Aug 8 '18 at 21:34

Since version 3.24, Gnome has a built-in blue light filter called Night Mode (AKA Night Light). It is now almost a proven fact that exposure to blue light in night-time disrupts our sleep pattern. Night Mode is there for that reason: to limit your exposure to both bright and blue light from the screen. It works by applying a red hue upon screen. So when it is turned on, blue color may look purple (this is the case here, see comments on the question).

Go to Settings > Devices > Display. There you can customize Night Mode by setting activation time or controlling red-level. Or you can disable the feature altogether.


You can also change it through commmand line.

| improve this answer | |
  • Although not related I am always curious about it? How to pronounce "Gnome"? Is it like "Go" for "Godzilla" and "no" for "necklace" pronounced one after another quickly? Like "Gonome"? – Sonevol Aug 8 '18 at 19:10
  • 2
    @Sonevol ubuntuforums.org/showthread.php?t=892670 – pomsky Aug 8 '18 at 19:25
  • 3
    It's worth noting (preferably in the answer) that Night Mode is there for a reason: to limit your exposure to both bright and blue light from the screen, both of which are thought to cause sleeping problems. Sure, disabling it is an option, but people should be made aware of the potential downsides of disabling it. – marcelm Aug 8 '18 at 20:39
  • And it rests your eyes. Without wearing properly coated glasses it damages your eyes. – Sonevol Aug 8 '18 at 22:16
  • 1
    @Sonevol “…it damages your eyes” [ Citation needed ] – Melebius Aug 14 '18 at 8:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.