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Author Topic: How to Fix GREEN Calibrated PA272?  (Read 3149 times)
kbellis
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« on: February 01, 2014, 09:03:26 AM »
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Hi,

Does anybody know how to get rid of the GREEN cast in the PA272?

After years of great performance and the LCD2690WUXi's perfect color this shift to - as my wife put it: "sea foam" is really pretty annoying ... and after spending the past four hours trying to find the answer, this is my first posting in an attempt to get some answers. I realize the issue is related to the type of backlighting with the PA272, but so far haven't found a decent reference on exactly how to deal with, or moreover, how to coax SpectraView to deal with it.

I've calibrated the monitor and everything at least from SpectraView II's behavior seemed perfect - v1.1.16.02 and the NVIDIA GTX 660 drivers are current (v332.21).

Thanks for any help Smiley

Kelly
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Czornyj
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« Reply #1 on: February 01, 2014, 09:14:31 AM »
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Run NEC Multiprofiler and enable metameric correction
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kbellis
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« Reply #2 on: February 01, 2014, 09:31:26 AM »
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SOLVED!

Thank you so much !!!
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kbellis
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« Reply #3 on: February 01, 2014, 09:51:29 AM »
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Do you know if there is a way to make Metamerism correction enabled by default?

It seems that the Metamerism correction afforded through MultiProfiler must be done after each calibration. Seems like that should be a preference setting more suited to being SpectraView - whatever.

I'm just thankful to have the green gone - thanks again - you really brightened up my day Smiley
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Czornyj
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« Reply #4 on: February 01, 2014, 10:54:02 AM »
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Sorry, but there's no way AFAIK - SVII disables metameric correction to calibrate and profile the display, but it doesn't enable that option afterwards.

Glad to hear it serves you well, all in all this is really a fantastic monitor Wink
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Frans Waterlander
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« Reply #5 on: February 01, 2014, 11:07:53 AM »
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I don't get it. Shouldn't this monitor be able to be calibrated without the green cast? Why the need to tweak after calibration?
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Czornyj
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« Reply #6 on: February 01, 2014, 11:27:17 AM »
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SVII calibrates the monitor using CIE 1931 2 standard observer, which is commonly used in GA industry. Problem is that due to effect of colorimetric additivity failure and observer metamerism a sensor that is measuring colour using CIE 1931 model "sees" monitor white point slightly different than human eye. Therefore displays with different backlight spectra look a little bit different after calibration, so that an additional correction must be applied to counteract this issue.
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Rand47
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« Reply #7 on: February 06, 2014, 08:05:21 PM »
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SVII calibrates the monitor using CIE 1931 2 standard observer, which is commonly used in GA industry. Problem is that due to effect of colorimetric additivity failure and observer metamerism a sensor that is measuring colour using CIE 1931 model "sees" monitor white point slightly different than human eye. Therefore displays with different backlight spectra look a little bit different after calibration, so that an additional correction must be applied to counteract this issue.

What wonderful and clever user-unfriendliness.

Rand
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Czornyj
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« Reply #8 on: February 07, 2014, 12:55:15 AM »
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Actually this is the most user friendly solution on the market.

In case of EIZO CX you need to buy a sensor, ColorNavigator License, and a function well hidden in the preferences to get rid of that. In case of Dell U24/2713H there's no option (other than eyeballing).
« Last Edit: February 07, 2014, 01:01:14 AM by Czornyj » Logged

Rand47
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« Reply #9 on: February 08, 2014, 04:54:31 PM »
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Actually this is the most user friendly solution on the market.

In case of EIZO CX you need to buy a sensor, ColorNavigator License, and a function well hidden in the preferences to get rid of that. In case of Dell U24/2713H there's no option (other than eyeballing).

I'm familiar w/ NEC as I own and love the PA271.   My comment is the SV II and the need for an extra step to get the profile correct w/ the 272.   Should be in the profiling run as an option, ergo is less user friendly and a step sideways if not backward.

Rand
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WombatHorror
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« Reply #10 on: March 01, 2014, 02:58:43 AM »
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SVII calibrates the monitor using CIE 1931 2 standard observer, which is commonly used in GA industry. Problem is that due to effect of colorimetric additivity failure and observer metamerism a sensor that is measuring colour using CIE 1931 model "sees" monitor white point slightly different than human eye. Therefore displays with different backlight spectra look a little bit different after calibration, so that an additional correction must be applied to counteract this issue.

I found the metamerism toggle made as many colors look even more different as made look more the same to a typical sRGB monitor. Plus the metamerism difference varies person to person so there is no one setting that would work ideally for everyone. You'd need a fully through and through spectral based color-management system to totally solve the problem (and a narrow band spectrophotometer as the probe).

Interestingly I found that the so-called green cast and other issues actually made an on screen color checker chart look MORE like a real life color checker chart viewed under D65 conditions than the so-called perfect cast of an sRGB made a color checker chart look. So between the toggle not making a perfect match anyway and my eyes matching the wide gamut monitor response better vs real life I was like to heck with the regular gamut monitors I'm not going to bother trying to match those. I don't intended to ever go back to editing on one of those anyway.

I wonder what the spectral spikes of OLED are like though. More like wide gamut LCDs or standard gamut LCDs? I hope the former.
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Czornyj
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« Reply #11 on: March 01, 2014, 07:11:10 AM »
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The problem is not related to observer variation nor sensor quality - it's a problem with CIE 1931 CMF. NEC PAxx2 series are calibrated with narrow band Konica-Minolta CS-2000 spectroradiometer, and all users are reporting agreeably they're observing a green cast, and after they enable metameric correction the display gets perceptually more neutral.

D65 is hypothetic illuminant, so may I ask how did you illuminate the CC using non existing light source? Anyway, it's not about monitor to print match, it's rather about monitor to monitor match.

I found the metamerism toggle made as many colors look even more different as made look more the same to a typical sRGB monitor. Plus the metamerism difference varies person to person so there is no one setting that would work ideally for everyone. You'd need a fully through and through spectral based color-management system to totally solve the problem (and a narrow band spectrophotometer as the probe).

Interestingly I found that the so-called green cast and other issues actually made an on screen color checker chart look MORE like a real life color checker chart viewed under D65 conditions than the so-called perfect cast of an sRGB made a color checker chart look. So between the toggle not making a perfect match anyway and my eyes matching the wide gamut monitor response better vs real life I was like to heck with the regular gamut monitors I'm not going to bother trying to match those. I don't intended to ever go back to editing on one of those anyway.

I wonder what the spectral spikes of OLED are like though. More like wide gamut LCDs or standard gamut LCDs? I hope the former.

« Last Edit: March 01, 2014, 07:22:20 AM by Czornyj » Logged

WombatHorror
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« Reply #12 on: March 01, 2014, 06:38:26 PM »
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The problem is not related to observer variation nor sensor quality - it's a problem with CIE 1931 CMF.

It is also related to observer variation as there variations in response to spectral spikes and ratios of various cell types that can skew how primaries with different spikes when used in a simple tri-stim color-management system look relative to one another.

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NEC PAxx2 series are calibrated with narrow band Konica-Minolta CS-2000 spectroradiometer, and all users are reporting agreeably they're observing a green cast, and after they enable metameric correction the display gets perceptually more neutral.

I'm not sure it is more perceptually neutral, is it really or is it simply closer to the typical look of a standard gamut LCD display?
As I said, if anything the real life color check chart whites looked a bit more like they did on non-metameric toggled wide gamut monitor to me, although in all three cases they looked different.
Maybe standard gamut LCD are closer, but I have some doubts.

Anyway the metamerism toggle maybe made the grayscales look a bit more similar but other tones became even more different so I didn't find the toggle really worked out so well. I'm pretty sure NEC ships the screens with metamerism toggle OFF by default.

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D65 is hypothetic illuminant, so may I ask how did you illuminate the CC using non existing light source?

Just got as close as I could using indirect sunlight of the proper atmospheric conditions and at the right time of day to get reasonably close.

Quote
Anyway, it's not about monitor to print match, it's rather about monitor to monitor match.


It depends what it is about. And soon enough standard gamut LCD tech will go the way of the Dodo. I don't know how LCD's of standard gamut have become THE thing to match now and forever.
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Czornyj
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« Reply #13 on: March 02, 2014, 06:31:30 AM »
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It is also related to observer variation as there variations in response to spectral spikes and ratios of various cell types that can skew how primaries with different spikes when used in a simple tri-stim color-management system look relative to one

I'm not sure it is more perceptually neutral, is it really or is it simply closer to the typical look of a standard gamut LCD display?
As I said, if anything the real life color check chart whites looked a bit more like they did on non-metameric toggled wide gamut monitor to me, although in all three cases they looked different.
Maybe standard gamut LCD are closer, but I have some doubts.
There's a distinct trend, that all users indicate they see a green cast, so logically it's not variation observer related issue, where each user would rather report different colour casts rather than definitely green. Let's say that after correction the display looks more pleasing, whether it's more neutral or not is indeed a moot question.

Anyway the metamerism toggle maybe made the grayscales look a bit more similar but other tones became even more different so I didn't find the toggle really worked out so well. I'm pretty sure NEC ships the screens with metamerism toggle OFF by default.

Just got as close as I could using indirect sunlight of the proper atmospheric conditions and at the right time of day to get reasonably close.

It depends what it is about. And soon enough standard gamut LCD tech will go the way of the Dodo. I don't know how LCD's of standard gamut have become THE thing to match now and forever.
So or so we don't know how close to D65 illuminant the light spectra was, and - while the comparison wasn't done at D50 - there's also additional CAT issue.
And it's not that strange that metamerism correction is toggled off by default, because CIE 1931 is still standard CMF in graphic arts industry, I believe.
It's all not about standard gamut LCD being the "golden standard", it's rather about getting inconsistent results with different display types - after calibration normal gamut CCFL looks slightly different than WG CCFL, which looks slightly different than GBr LED, which looks slightly different than OLED, and so on...
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Czornyj
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« Reply #14 on: March 02, 2014, 08:36:11 AM »
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I wonder what the spectral spikes of OLED are like though.

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WombatHorror
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« Reply #15 on: March 03, 2014, 03:17:47 AM »
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OK now I wonder what CCFL wide gamut and the new type of LED backlight spectra look like.  Wink Grin

I'm pretty sure the CCFL ones are a LOT spikier though right?

Anyway an interesting quote I found, getting to my point about observer to observer differences for different display technology is this from a color scientist in answer to someone's question:
"Q:    Is there enough variation in individual retinal sensitivity that broad spectrum stimuli are required?
A: Yes. Definitely. I haven't studied enough about the visual system to know how broad/varied, although I doubt there's one definitive answer.""

which fits right with what I said.
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