[argyllcms] Re: Calibrator correction for Eye One Display 2 & GB-LED Backlight LCD Monitor?

  • From: Milan Knížek <knizek.confy@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 30 Jul 2014 14:40:27 +0200

Hi Graeme,

thanks for the write up a year ago, I could have saved some time if I
found it earlier ;-)

One question forcing me to revive the old topic though: you mentioned
that

x "fakeread values are normalised to 100"

x meaning that dispread values are not normalised to 100

and therefore the LUMINANCE_XYZ_CDM2 should be copied from dispread
test.ti3 to fakeread ref.ti3 file.

My confusion stems from the test.ti3 (produced by dispread), which reads
that the numbers _are_ normalised:

KEYWORD "LUMINANCE_XYZ_CDM2"
LUMINANCE_XYZ_CDM2 "66.758160 61.640342 95.172183"
KEYWORD "NORMALIZED_TO_Y_100"
NORMALIZED_TO_Y_100 "YES"
...
BEGIN_DATA
1 100.000 100.000 100.000 108.303 100.000 154.399
...


Is your hint re. copying of LUMINANCE_XYZ_CDM2 values from test.ti3 to
ref.ti3 still valid nowadays?


BTW, my vendor tailored Huey for Samsung SyncMaster XL20 seems broken
(all of sudden there is too much green after calibration), hence I had a
similar idea as the original poster to re-use my Eye-one Display 2 and
rely on Samsung's emulated sRGB to create the correction matrix.

I may end up buying a new monitor anyway, just giving it a try. The
first impression is that the correction matrix works - I use it for
profiling in "custom mode / native colour space" of the display.

regards,
Milan


-- 
http://milan-knizek.net/
About linux and photography (Czech only)
O linuxu a fotografování


Graeme Gill píše v Čt 05. 09. 2013 v 12:51 +1000:
> Al Robertson wrote:
> 
> Hi,
> 
> > The NEC has become dim over time and I'm looking to replace it soon with an
> > Asus ProArt PA249Q which, like the better known Dell U2413, has the LG
> > LM240WU9-SLA1 AH-IPS panel. But I have one problem.
> 
> > This relatively new panel has a GB-LED backlight (improved gamut), but from
> > what I've read, the curves are sufficiently different that I would need to
> > either go buy a new calibrator (X-Rite wanted to sell me the i1Display Pro -
> > $229), or get a new correction matrix to successfully use my existing
> > colorimeter.
> 
> The i1Display Pro is a pretty solid instrument, and well worth
> the investment.
> 
> > Does anyone have a corrections file for the Eye One Display 2 and a GB-LED
> > backlight display? Or perhaps be thinking about either making one, or
> > including GB-LED support into argyllCMS/dispcalGUI as a new mode?
> 
> The variability of the instrument is such that I'd be a bit suspicious
> of a correction matrix made for a different instance of the i1d2.
> 
> > If not, any ideas on how to make or fake one at home?
> 
> The best way of course is to use a spectrometer (ie. i1pro or ColorMunki 
> spectro.)
> as a reference on your display against your i1d2.
> 
> > One idea.The monitor claims  to come factory calibrated within 3 delta E
> > (fingers crossed.) Is there at least a way to make a correction file that
> > uses the factory calibration as a trusted baseline so I can always get back
> > to that even if the colors drift over time (or if I want to customize the
> > calibration)?
> 
> OK, here's an outline of how you might go about this. I'm
> leaving out some details, and I haven't actually tried it,
> so you may well need to troubleshoot the procedure:
> 
> Create a reference test set of (say) a 3^3 or 4^3 cube set using
> targen, ie. something like:
> 
>     targen -v -d3 -e0 -B0 -m3 -f0 test
> 
> Copy this to a reference set:
> 
>     copy test.ti1 ref.ti1
> 
> Set your new display to (say) sRGB mode, and measure the
> test set with your instrument.
> 
>     dispread -v -yl test
> 
> Create a reference set using the sRGB.icm file, that we
> assume the new display is calibrated to:
> 
>     fakeread -v sRGB.icm ref
> 
> A problem with this is that the real readings will be
> returned to absolute values (cd/m^2), whereas the fakeread
> values are normalised to 100, so we will have to make sure
> that the fakeread values get scaled the same way.
> 
> Open the test.ti3 file in a text editor and copy the
> LUMINANCE_XYZ_CDM2 line, ie. for the sake of an example:
> 
>   LUMINANCE_XYZ_CDM2 "46.509281 49.445099 45.615122"
> 
> into the ref.ti3 file in a similar position. This should
> cause the values to be scaled to match the instrument values.
> 
> Create a ccmx correction matrix from the ref and test results:
> 
>     ccxxmake -v -f ref.ti3,test.ti3 correction.ccmx
> 
> You can then use the correction matrix with your instrument
> on that display, ie.
> 
>     dispread -yl -X correction.ccmx etc.
> 
> Graeme Gill.
> 
> 


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