[argyllcms] Re: Is the i1D3 (ColorMunki Display) accurate?
- From: Roger Breton <graxx@xxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Fri, 27 Jul 2012 08:08:13 -0400
I don?t know what to make of absolute accuracy anymore?
Last year, I decided to buy a Minolta CS-200 colorimeter ? not a bad
instrument (if only it was supported in argyll?). But I am disappointed? I
recently sent it in to Minolta for re-certification so I can reasonably
trust its measurements to have some value. OK. It?s not an LMT colorimeter
and it?s not a spectroradiometer either. Although it is said to use
spectroradiometric types of light measurements internally.
I?m in a situation where I am comparing a hardcopy proof to the image on a
screen. Regardless of the absolute accuracy of the instruments that are used
to calibrate the screen and the printer, the fact of the matter remains
that, although I am able to bring both the gray patch on the proof and the
screen to yield the SAME EXACT 2 degrees chromaticities on my CS-200, to the
fourth digit precision, thank you, I have to report that, visually, the two
stimulus don?t match to my eyes!
Is it because my eyes don?t correspond all that closely to the Standard
Observer color matching functions?
Is it because there are optical effects I am not aware of?
Would a true spectroradiometer yield better agreements between the two
stimulus?
Is it the light that is throwing a monkey wrench into the equation
(JUST-Normlicht)?
Chances are I?ll never find the definitive answer to this holy grail quest.
That?s why when I see tons of discussions on absolute accuracy, I am tempted
to take them with a grain of salt.
What do you think?
Would it be possible to develop some kind of linear correction model à la
correction matrix for colorimeters?
Best / Roger
From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx]
On Behalf Of Stephen T
Sent: July-27-12 7:29 AM
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Re: Is the i1D3 (ColorMunki Display) accurate?
The i1D2 is less than two years old. I've kept it well stored, with silica
gel desiccant.
Stephen.
From: "János, Tóth F." < <mailto:janos666@xxxxxxxxxx> janos666@xxxxxxxxxx>
To: <mailto:argyllcms@xxxxxxxxxxxxx> argyllcms@xxxxxxxxxxxxx
Sent: Friday, 27 July 2012 8:27 PM
Subject: [argyllcms] Re: Is the i1D3 (ColorMunki Display) accurate?
How old is your i1d2?
2012/7/27 Stephen T <stwebvanuatu@xxxxxxxxxxxx>
Hello Janos,
Thankyou for your constructive advice.
There are two issues: 1) accuracy and 2) unit-to-unit variability:
http://www.drycreekphoto.com/Learn/Calibration/MonitorCalibrationHardware.ht
ml
OEM i1D2 variability DE00 = 4 - 7, average white point accuracy DE00 = 2 - 4
i1D3 variability DE00 = 0.4 - 2, average white point accuracy DE00 = 2 - 3
In the worst case, any two instruments might disagree by DE00 = 2 + 7 = 9.
My results show a difference of DE00 = 12.
I also measured white patches with spotread and calculate DE94 = 14.
I suppose that luminance measurements are fairly robust and my i1D3 does
appear to be an odd unit in two tests.
I think my i1D3 is measuring out of tolerance?
Has anyone else experienced similar and have they measured the difference?
I'm not throwing my Spyder2 in the bin just yet.
Stephen.
From: "János, Tóth F." <janos666@xxxxxxxxxx>
To: argyllcms@xxxxxxxxxxxxx
Sent: Friday, 27 July 2012 7:00 AM
Subject: [argyllcms] Re: Is the i1D3 (ColorMunki Display) accurate?
I think you bought a new sensor because you believed it's better than your
old. Didn't you?
The i1d3 is more accurate in theory. The hardware is better, the corrections
are smarter.
Of yourse, it's not "perfect". (Neither any other relatively cheap
instruments are.) But I guess you will be happy with the i1d3 if the i1d2
was good enough for your needs.
2012/7/26 Stephen T <stwebvanuatu@xxxxxxxxxxxx>
Hello,
I received my ColorMunki display this week and have been doing some
comparisons. It gives different readings to my OEM i1D2.
I calibrated my wide gamut NEC P221W display with X-Rite's ColorMunki
Display software and the following settings:
native white point (hardware setting), D65, gamma = 2.2, brightness 120
cd/m2 (adjusted in hardware), WGCCFL display type (under preferences!), no
ambient adjustment, no flare correction.
I then measured the response in Argyll CMS v1.4.0 with the profile loaded in
Windows 7. I measured with two instruments: ColorMunki Display and NEC
MDSVSENSOR (OEM i1D2). I also measured without the CCSS matrix. The profile
was good when measured with the i1D3 and so I believe Argyll CMS is not at
fault. The profile was inaccurate when tested with the i1D2.
Are the i1D3 generic correction matrices accurate? My MDSVSENSOR suggests
the white point DE00 = 12 and brightness is 8 cd/m2 brighter.
Has anyone else tested the accuracy of the i1D3 against other instruments,
especially spectrophotometer?
Are the generic correction matrices accurate for some display technologies
and inaccurate for others? I assume the MDSVSENSOR is accurate for wide
gamut NEC displays. I bought the ColorMunki Display mainly for standard
gamut CCFL and WLED displays and now I am hesitant to use it!
Maybe one of my colorimeters is faulty?
Stephen.
Here are the results:
i1D3 + CCSS
----------- ---
C:\Users\Stephen>dispcal -d 1 -y l -X WGCCFLFamily_07Feb11.ccss -r -P
0.5,0.5,2.0
Place instrument on test window.
Hit Esc or Q to give up, any other key to continue:
Current calibration response:
Black level = 0.12 cd/m^2
White level = 119.57 cd/m^2
Aprox. gamma = 2.18
Contrast ratio = 1004:1
White chromaticity coordinates 0.3108, 0.3274
White Correlated Color Temperature = 6622K, DE 2K to locus = 4.8
White Correlated Daylight Temperature = 6622K, DE 2K to locus = 0.2
White Visual Color Temperature = 6442K, DE 2K to locus = 4.6
White Visual Daylight Temperature = 6614K, DE 2K to locus = 0.2
The instrument can be removed from the screen.
OEM i1D2 (NEC MDSVSENSOR)
------------------------- ------------
C:\Users\Stephen>dispcal -d 1 -y l -r -P 0.5,0.5,2.0
Place instrument on test window.
Hit Esc or Q to give up, any other key to continue:
Current calibration response:
Black level = 0.12 cd/m^2
White level = 127.53 cd/m^2
Aprox. gamma = 2.17
Contrast ratio = 1026:1
White chromaticity coordinates 0.3135, 0.3503
White Correlated Color Temperature = 6328K, DE 2K to locus = 14.4
White Correlated Daylight Temperature = 6321K, DE 2K to locus = 12.0
White Visual Color Temperature = 5810K, DE 2K to locus = 14.1
White Visual Daylight Temperature = 5924K, DE 2K to locus = 11.6
The instrument can be removed from the screen.
i1D3
-----
C:\Users\Stephen>dispcal -d 1 -y l -r -P 0.5,0.5,2.0
Place instrument on test window.
Hit Esc or Q to give up, any other key to continue:
Current calibration response:
Black level = 0.12 cd/m^2
White level = 118.54 cd/m^2
Aprox. gamma = 2.17
Contrast ratio = 1002:1
White chromaticity coordinates 0.3013, 0.3325
White Correlated Color Temperature = 7100K, DE 2K to locus = 12.4
White Correlated Daylight Temperature = 7090K, DE 2K to locus = 9.6
White Visual Color Temperature = 6517K, DE 2K to locus = 12.0
White Visual Daylight Temperature = 6666K, DE 2K to locus = 9.3
The instrument can be removed from the screen.
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