[argyllcms] Re: General calibration questions
- From: Kai-Uwe Behrmann <ku.b@xxxxxx>
- To: Andrés Vattuone <andres.vattuone@xxxxxxxxx>, argyllcms@xxxxxxxxxxxxx
- Date: Sun, 09 Oct 2011 15:35:20 +0200
Am 08.10.2011 06:55, schrieb Andrés Vattuone:
> Thanks for each and every answer, Kai-Uwe.
> All my questionaire stems from the fact that, since there are no v4
> profiling options in Linux, i was planning to create a profile under
> Windows and export it to linux afterwards. Then I realised that the
> proflles not only store icc information but also video card
> information to be uploaded. It is therefore essential to know exactly
> which information it stores unless I decide to stick to windows and
> proprietary sofware. Or else I should abandon v4 profiling.
I am not aware, that ArgyllCMS will support v4 profiles right now.
> I am trying to transport calibration settings from one OS to another.
That should be possible.
> >The Apple developers docu has informations.
>
> Trivial as it seems, I can't find the vcgt tag specification. I did
> find some mails written by Marti and have infered from them that the
> vcgt tag just stores three curves with 256 values each. Is that right?
Wrong. See:
http://developer.apple.com/library/mac/#documentation/GraphicsImaging/Reference/ColorSync_Manager/Reference/reference.html#//apple_ref/doc/constant_group/Video_Card_Gamma_Tags
> >> 3) Do different loaders behave differently?
> >
> > Some fail, while others do not. The usual habit. But they do mostly
> they job reliably.
> >
>
> The question was aimed at knowing if they load white point, brightness
> or other settings to the video card, and what exactly loading means.
> In the end the question would be: what is capable of being loaded to a
> graphic card? Just curves, or also bounds, matrix transforms, etc? In
> other words, let's say you can tell a video card to set a certain
> white point. Do you do this by modifying curves?
They OS functions care about graphic card settings. These can affect
brightness and certainly white point. But again, these are not identical
to monitor internal settings.
> >> 4) Appart from Gamma curves do they load anything else?
> >
> > Some load these three curves only, some take over as well the ICC
> profile to X upload. E.g. Oyranos uses xcalib, while GCM uses own code
> or gdk.
>
> I don't know what X upload means. Does it mean setting the profile as
> default in the system without modifying anything in the video card?
X is the most common windowing system on Linux/BSD, with the exception
of osX. The ICC profile contains VCGT data. The standard ICC parts and
the non standard VCGT part can be used technical independently. Thats
appearant on Windows and Linux/X11.
> > The "X server gamma ramp" points to the XFree86/Xorg APIs. The other
> >way would be to talk to the graphic card driver, which is barely used
> if at all.
> >
>
> So in the end they effectively modify the video card luts through the
> XFree86/Xorg api. Right
yes
kind regards
Kai-Uwe Behrmann
--
www.oyranos.org
Other related posts:
