[argyllcms] Re: problem loading LUT-based icc profile to CRT

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 09 Dec 2009 19:26:13 +1100

David Heinrich wrote:
I've made a LUT-based profile and am trying to load it (where are they
loaded anyways, system software, gpu, monitor?).

The 'vcgt' tag is loaded into the graphic card hardware to calibrate
the monitor. It's up to applications to load the profile to access
the monitor characterization information, so that they are
able to transform colors into the calibrated monitors colorspace.

See <http://www.argyllcms.com/doc/calvschar.html>

When alternating between
clearing profiles from the system and loading my LUT-based profile, I see a
quick flicker on the screen (but not one of the audible ones where the CRT
makes noise). However, I don't notice any change in my ~18% neutral gray
desktop background.

Maybe the monitor has a native characteristic very similar to
the calibration target ?

Have you tried loading "strange.cal" from the argyll ref directory,
to get a more obvious visual indication that the calibration gets loaded ?

I have a Sony GDM-F520 CRT monitor, 2048x1536. xrandr reports detected EDID
modes, so I'm not sure why I'm getting these weird "Failed to get EDID for
display" messages. (DVI-I_2/analog is my CRT, I'm not using the other one at
the moment).
$ sudo /opt/Argyll/bin/dispwin -v -c; dispwin -v -E 9 -V

Verify: 'colprof-sony-gdm-f520-3000-patches-12-6-2009.icc' is NOT loaded
(discrepancy 12.2%)

*$ sudo /opt/Argyll/bin/dispwin -v -E 9 -I
colprof-sony-gdm-f520-3000-patches-12-6-2009.icc ; dispwin -v -E 9 -V

Verify: 'colprof-sony-gdm-f520-3000-patches-12-6-2009.icc' IS loaded
(discrepancy 0.0%)

Seems like the calibration gets loaded as far as the software
is concerned.

*$ xrandr*

Try running xrandr --prop and see whether you can see the EDID property.
Is it called "EDID_DATA" or something else ?
If it's not there or not accessible because it's called something else,
then that's why the warnings about it.

Have you tried V1.1.0 RC2, it has a couple of fixes in this area, and
will locate the EDID data from either the "EDID_DATA" or "EDID" output property.

Graeme Gill.

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