[argyllcms] Re: AW: Matrox P650 doesn't seem to want to play...

  • From: Neil Woolford <neil@xxxxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 13 Dec 2006 21:08:47 +0000

On Wed, 2006-12-13 at 14:21 +0000, Neil Woolford wrote:
> Thanks for the swift and helpful responses guys.
> On Wed, 2006-12-13 at 23:18 +1100, Graeme Gill wrote:
> > Thomas Kumlehn wrote:
> > 
> > > I'm not sure if this is related to the P650, but some graphics cards have
> > > great 10bit LUTs but bypass them when outputting digitally over DVI, just
> > > because they are placed by design between Memory path and DAC and not also
> > > between Memory path and DVI chip. Currently no off-the-shelf LCD known to 
> > > me,
> > > takes 10bit per colour channel. All need 8x3bits.
> > 
> > If the design of the card is such that the LUTs are only in the D/A
> > path, then calibration isn't going to work. I'd be a little surprised if
> > Video cards are designed that way (how are gamers going to adjust
> > their gamma ?), but it's certainly possible. Of course DVI makes
> > it impossible/non-standard to use more than 8 bits/component,
> > so an Video cards LUTs will be 8x3 to the DVI.
> It sounds horribly like what may be happening.  No error message when
> writing to the LUT, but no effect either.  That could mean I'm
> successfully writing to the table but it has no effect on the outputs
> that I'm using.  I suppose I have to hope that the main screen (a
> Formac) lives up to the manufacturer's claim of great image quality
> straight out of the box.  The second monitor is just for palettes and
> tools so really a manual adjustment to a non-offensive visual match on
> the white would be enough for comfort.
> Next thing I'll try is reverting the secondary display to analogue
> connection and see what happens then when I run dispwin -r on it.  If
> that works, then I think we have our answer.  I'll research the Formac
> documentation, just in case there is something internal to the monitor.

Still no joy.  Dispwin works as far as displaying colour squares goes,
but no overall brightness change, even with the monitor connected via
the analogue cable.

> I'm using the mta driver in X, which I did have to install specially;
> there appear to be some kernel modules which are associated with this
> which didn't compile successfully - I think that looses me 3d gizmos
> that I don't use, but there may be other things of importance lacking
> because of that.  I'll check that.

That should be mtx driver of course.


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