[argyllcms] Re: nVidia GeForce & deep colour support in Linux

  • From: Milan Knížek <knizek.confy@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Mon, 01 Sep 2014 21:52:03 +0200

Kai-Uwe Behrmann píše v Ne 31. 08. 2014 v 22:00 +0200:
> On 30. August 2014 22:29:55 MESZ, "János, Tóth F." <janos666@xxxxxxxxxx> 
> wrote:
> >
> >2014-08-30 21:52 GMT+02:00 Marwan Daar <marwan.daar@xxxxxxxxx>:
> >> Not sure if this is helpful, relevant, or even meaningful, but my
> >> understanding is that regular geforce cards only support 10 bit in a
> >directx
> >> environment, whereas you need the quadro for 10 bit open gl support

I have tried to get some info from devtalk Linux forums of nVidia. (59
views, no response yet.)

The README mentions few bits about the requirements:

This driver release supports X screens with screen depths of 30 bits
per pixel (10 bits per color component). This provides about 1 billion
possible colors, allowing for higher color precision and smoother
gradients.     When displaying a depth 30 image, the color data may be
dithered to lower bit depths, depending on the capabilities of the
display device and how it is connected to the GPU. Some devices
connected via analog VGA or DisplayPort can display the full 10 bit
range of colors. Devices connected via DVI or HDMI, as well as laptop
internal panels connected via LVDS, will be dithered to 8 or 6 bits per

To work reliably, depth 30 requires X.Org 7.3 or higher and pixman
0.11.6 or higher.     In addition to the above software requirements,
many X applications and toolkits do not understand depth 30 visuals as
of this writing. Some programs may work correctly, some may work but
display incorrect colors, and some may simply fail to run. In
particular, many OpenGL applications request 8 bits of alpha when
searching for FBConfigs. Since depth 30 visuals have only 2 bits of
alpha, no suitable FBConfigs will be found and such applications will
fail to start.

> Opengl works fine with 30-bit visuals under xorg, be it Krita, Compiz,
> KWin or ICC Examin. xwininfo -root | grep Depth Shows me Depth: 30.
> That means any application, which is capable to encode 10-bit bit per
> plane can display 30-bit. It is merely a question to find a toolkit in
> support of that. Using xlib directly should enable applications for
> high bit depth, which is mostly abstracted away by linux graphics API's

I can run X server also with 30-bit depth (X.org log confirms it) with
32 bpp framebuffer (so only 2 bits are for transparency). I have found
the same info in Xorg.log posted on the internet forums by some Quadro
card user.

I also checked with Dell U2713H support community forum that the LCD
actually has 10-bit input and works with MS Windows + Quadro / Firepro +

> these days. The more easy way is using OpenGL.
Is there anything special for Krita to display in 30-bit depth other
than to choose "Enable OpenGL" in Preferences / Display and load a
16-bit encoded image? I used Compiz as WM.


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