[Openicc] Re: xcalib in Oyranos package
Hal V. Engel
hvengel at astound.net
Tue Oct 18 06:41:15 EST 2005
On Monday 17 October 2005 12:16 pm, Chris Murphy wrote:
> On Oct 16, 2005, at 10:55 AM, Hal V. Engel wrote:
> > In addition as far as I know on Windows you can't even specify
> > different
> > profiles for monitors that are attached to the same video card. I
> > know for
> > a fact that this is true for my Matrox card. The Windows driver
> > standard for
> > video cards simply does not support color managing more than one
> > display per
> > video card. Until that changes video card manufacturers are not
> > likely to
> > implement more than one LUT per GPU. Does anyone know if this has
> > changed in
> > Longhorn?
> I know you can do this in XP because I've seen it. It would depend on
> the hardware actually having separate DAC LUTs for port, and a driver
> that took advantage of it. What I can't remember is the user
> interface; whether it shows up as though it's a single card but has
> two color management tabs to associate separate profiles for the two
> displays; or if it shows up in UI as though it's two separate video
Separate profiles for each monitor on the same video card might be possible
but I know that it is not with any cards/drivers from nVidia or Matrox.
Since I have a Matrox card and am considering getting an nVidia card I have
asked support for both companies and they both say no you can't have
different profiles for each display if the displays are connected to the same
video card. nVidia says to get a second video card. No nVidia card
supports more than one LUT per card.
I think you are correct about having separate LUTs for each output port on the
newer Matrox cards. In fact I just checked on the Matrox web site and the P
series cards have a LUT for each supported output port (2 on the 650 and 3 on
the 750). But you can not specify different profiles for each monitor on the
same card. There are dozens of posts on the Matrox user forum about this.
Here is what Matrox says " Note that when in WinXP, the OS will not allow you
to load 2 ICC profiles. In this case, the software developer will have to
modify their application in order for it to work on multi head cards."
Matrox used to make a big deal about the P series being capable of being
color managed in dual head mode. But because of the problems with the
Windows driver spec they no longer make this claim since there was a
significant user backlash.
Just as a side note Matrox has not yet released a driver for the P series
cards that will work on an amd64 machine that is running a 64 bit X
installation and even on x86 systems the drivers are still problematic.
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