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Thread: 10-bit palette / 30-bit colour depth

  1. #1

    Question 10-bit palette / 30-bit colour depth

    Hi everyone,

    I'm trying to get the most out of my Nvidia GTX970 and BenQ CAD monitor by switching from an 8-bit colour palette to 10-bit. The switch is easy enough by changing two lines in the xorg.conf file from 24 to 30 as per the Nvidia linux driver documentation. The issue I'm having is with KDE and KDE native apps, such as Konqueror: the window decorations are all messed up, and its hard to read anything in Konqueror (for example). I've confirmed with xwininfo that the new app windows now have a 30-bit depth...so I don't think its a Nvidia issue.

    I'm running a plain Leap 42.2 install with KDE (not Gnome)...so is this a SuSE config thing/problem or do I need to contact the KDE folks?

    Thanks,

    Jim.

  2. #2

    Default Re: 10-bit palette / 30-bit colour depth

    I've had an interest in 10bit colour for photography. I stopped looking at it when I found that there were limitations on the maximum screen resolution that could be obtained with the monitor connections that were available at the time, a couple of years ago. It also mainly aimed at photographic printing in this area.

    You could try installing colour management. 10bit colour implies adobe rgb and if that isn't handled correctly colours can shift due to the need to translate them to different colour spaces. A search for colour management in YAST does show one based around Oyranos. That was installed by default on my previous opensuse which was 12.3.

    I can't say that this will fix your problem but they may have accounted for different colour depths in it. The settings going on 12.3 will be in kde's system settings.

    The other aspect is that when 10bit is used in photography it's generally viewed in applications that can make use of a colour profile. In my case using sRGB as I calibrate my monitor I have to install the profile system wide to account for the fact that not all of the applications I use are colour managed. If I had a 10bit monitor as far as I am aware I could only view images at that depth via an application that could accept a suitable colour profile. Other applications that could only make use of 8bit would also need a colour profile. You might find that kde can display colours correctly in 10 bit and that the cad package can't or things could be the other way round. I'd expect the cad package to state that it can if it will.

    John
    -
    Leap 42.2 KDE 5.26
    3.6gig Xeon, 64bit SATA Raid home - Linux Raid 1
    All software on a flash drive, SATA swap & Temp files,

  3. #3

    Default Re: 10-bit palette / 30-bit colour depth

    Hi John,

    I've done my research before purchasing the monitor and video card, and made sure I picked the products that would support the 10-bit colour palette. Definitely it came down to things, such as using only Display Port connections, and ensuring the video card and monitor support sRGB and/or Adobe profiles. The monitor I chose is the BenQ BL3200, a 32" monitor with a resolution of 2560x1440, with 100% support for the sRGB colour gamut. Then I used a ColorMunki Display device to calibrate the monitor and create a custom ICC profile, which I've loaded into x-windows and I'm also using the colord daemon to ensure compatibility across both QT and GTK apps.

    My primary use case is editing RAW pictures from my Canon camera in DarkTable. I've confirmed that DarkTable has picked-up the custom ICC profile and is using the full 10-bit palette/30-bit colour depth, so I'm good there.

    Since writing the post last night I came across this page: http://www.oyranos.org/tag/opensuse/

    Under the title "Image Editing with 30-bit Monitors" there was a suggestion to:

    Create following text into a file called ~/.kde4/env/qtnative.sh

    $ kwrite ~/.kde4/env/qtnative.sh

    #!/bin/sh
    export QT_GRAPHICSSYSTEM=native

    Which didn't work with Leap 42.2, so I put the same file in the /etc/profile.d folder, after a reboot the KDE apps look much better...but the window borders still look weird and there is also a strange flicker when opening applications...hard to describe.

    As the price of 4K monitors with UHD (10-bit colour palette) become more and more reasonable in price I believe this issue will happen more often in the near future.

    In "System Settings -> Appearance -> Colour Management" I made the necessary selections, which I'm not entirely sure what they do. I'm guessing its for compliant applications to read the ICC settings and such...but it doesn't seem to make a difference on the KDE window problem I'm having. Perhaps its just a matter of finding the proper "Application Colour Scheme".

    Thanks,

    Jim.

  4. #4

    Default Re: 10-bit palette / 30-bit colour depth

    Just tried something which may have corrected all my visual issues: I enabled the compositor on startup with the default settings.

    So far everything looks good...so far so good that is. There are a still a few small graphic anomalies which I might need to look into...but for the most part things are a lot better.

    If anything changes I'll post on here to let folks know for future reference.

  5. #5

    Default Re: 10-bit palette / 30-bit colour depth

    It's not called discalgui any more but a google will bring up a gui application that drives argyll colour management. You might find that better than what ever came with your colorimeter. It can also be used with some spectrometers where similar software increases their cost.

    Or you may be using it already. One thing it will do is install profiles system wide as well as a set for for applications. A run with it can take 20min and it does a pretty precise job. There is a forum too for the gui for if there are any problems.

    Personally I use rawtherapee and the gimp for layer work and for some of it's plugins. Also often fotoxx for all sorts of things. Most shots I take spend some time in that.

    John
    -
    Leap 42.2 KDE 5.26
    3.6gig Xeon, 64bit SATA Raid home - Linux Raid 1
    All software on a flash drive, SATA swap & Temp files,

  6. #6

    Default Re: 10-bit palette / 30-bit colour depth

    Yes..it's now called DisplayCAL...which is what I used. The software that came with the calibrator only works on Windows or MAC. DisplayCAL was awesome...and it did a great job. I was happy to discover that my monitor was really close and didn't need too much to make it colour accurate. At the end of the analysis, it was super easy to install the ICC profile...basically click a button! Very nice app.

    Have you taken a look at DarkTable? It's a bit of a learning curve, but I'm liking it more and more as I use it. The authors really need more tutorial type videos...but other then that it is very powerful.

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