Leonardo Facchin wrote:
Hi,
The laptop graphics system makes use of the nVidia Optimus technology.
Beware - it's been reported that igfxpers.exe that gets installed with nVidia
"Optimus"
technology interferes with Video LUT loading. I'm told that you may have to
disable both
the igfx tray module (c:\windows\system32\igfxtray.exe) and the igfxpph Module
(c:\windows\system32\igfxpph.dll) in addition to the persistence Module
(c:\windows\system32\igfxpers.exe). I have no idea what effect that has on the
system
operation though.
If nVidia have fixed these problems it would be good to know, so that I
can update the documentation.
The problem is that right now I'm totally lost and confused about how the "two"
graphics
cards actually interact with the calibration and profiling process. Let's
assume that I
could force both the relevant Adobe softwares to run with the nVidia GPU (which
I did) and
the Argyll CMS components to do the same (which I didn't: even if I associate
the Argyll
executables to the nVidia GPU, when I run them the GPU remains idle, at least
according to
the nVidia Optimus GPU State Viewer, a little software meant to show when the
GPU is
powered up and running).
ArgyllCMS doesn't use the GPU, so I wouldn't expect an association to do
anything.
Still, how can I know how many LUTs the system can access and which graphics
card control
each of them? Could the two cards be sharing the LUTs? Does it even make sense?
The Video LUT is logically associated with a Video output port, so if it's been
implemented correctly, there should be only a single set of LUTs, probably in
the
Intel hardware if it's driving the HDMI port, but in any case there is only
a single operating system API per display. Now, they may messed all that
up (hence the feedback that igfxpers.exe is a problem.)
I know that the easiest solutions would probably be to stick to the Integrated
Processing
Unit and be done with it, but on the one hand the total confusion is
undermining my trust
in the accuracy of my color managed workflow and on the other I just developed
the
curiosity to understand a little better how this system works.
It's usually not that hard to figure out what's going on. Use dispwin -c to
clear the VideoLUTs, and dispwin strange.cal to set a noticeable LUT. That
will tell you whether calibration loading is working as expected.
<http://www.argyllcms.com/doc/dispwin.html>
Graeme Gill.
