• How To Get Full RGB Color with your HDMI Connected Monitor With Linux

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    #221388

    If you have a monitor connected via HDMI and the colors seem a little pale, and the blacks look sorta dingy, it’s not your monitor.

    For some reason most Linux distros default to “limited RGB” which uses 16-235 on the RGB scale, not the full 0-255 when sending the video signal through the HDMI port.

    DVI is not affected by this.  I don’t know about Display Port.

    There is an easy fix that took me a few weeks to find on the internet.

    You will need to open the terminal and enter;

    xrandr – -verbose.

    Scroll to the part of the readout that corresponds to your HDMI port.  Note what it’s nomenclature is, you will need it later.  Don’t close the terminal just yet either.

    You will note in the pic mine is labeled HDMI1.  You will also see that the Broadcast RGB is set to Automatic.  It always says that, but it will be outputting Limited 16:235.

    In the terminal type;

    xrandr – -output  (your port designation goes here) – -set “Broadcast RGB” “Full”

    For example, mine would look like this.

    xrandr – -output  HDMI1 – -set “Broadcast RGB” “Full”

    Hit enter.  Your screen will blank out for about a second, when it comes back on you will see the improved colors and deeper blacks.

    If you enter xrandr – -verbose again, your output should read like this, with Broadcast RGB set at Full.

    This change is not persistent, when you reboot it will revert back to Limited again.  However, there is an easy solution with any of the Mint flavors, including KDE, up through 18.3.  I haven’t tried it with 19.0, so I can’t say for sure.

    Go to your profile in your home folder, (you will need to enable show hidden files).

    After you open your profile with your favorite editor, enter the same line you entered in the terminal earlier, at the end of the profile.

    xrandr – -output  (your port designation goes here) – -set “Broadcast RGB” “Full”

    Now save the change and close out of the editor.

    Now when you boot, the output setting will always be “Full”.

    I couldn’t get the profile change to work with Solus.

    I don’t like Ubuntu, I never got past the test drive from a USB drive, so I never had a reason to try the profile change with that distro.  Seeing how Mint is based off of Ubuntu, I would think it would work.  Same with any other Ubuntu based distro.

    I didn’t try it with any Arch based distro.  One will possibly have to find another fix with those.

     

     

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    • #221730

      I checked my desktop and my laptop to look for this (I had never heard of it before now!), and my desktop doesn’t have the Broadcast RGB section.  It’s on an nVidia GPU with the proprietary driver, and the best I can tell, is using the same signal format (TMDS) as with the DVI ports.

      The Swift laptop, however, uses Intel integrated graphics (using the modesetting driver), and it does in fact look just like what you have shown here.  I’ve never actually used the integrated HDMI port on the laptop!

      Anyone have an AMD card to see how it looks?

      Thanks again for the info.

       

      Dell XPS 13/9310, i5-1135G7/16GB, KDE Neon 6.2
      XPG Xenia 15, i7-9750H/32GB & GTX1660ti, Kubuntu 24.04
      Acer Swift Go 14, i5-1335U/16GB, Kubuntu 24.04 (and Win 11)

    • #227590

      I wonder if this is a similar issue under Windows. Here is what I found.

      FWIW, on the install of my newest nVidia display driver (411.70) for Windows 7, in the nVidia Control Panel there is a setting for Output Dynamic Range. I had never noticed it before. It was set by default to Limited by the driver installer. When I hovered over the pull down menu, it said to select full range (0-255) for 8bpc rather than limited (16-235), if you wanted more detail in the dark and white areas. I tested it and it was night and day on the desktop and for viewing photos. It was less so for gaming.

      I wonder if this is the setting you are tweaking in terminal. My current monitor is a 32″ HDMI monitor which always looked a bit less vibrant than the prior 27″ DVI monitor. It now appears very similar.

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