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Author Topic: NEC PA 301W  (Read 4852 times)
Wayne Fox
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« on: May 11, 2011, 09:34:29 PM »
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Finally decided to bite the bullet and move to a wide gamut display.  I've been experimenting with calibrating it with varying degrees of success.  I finally was able to get a nice display to print match, but only after doing a couple of slight manual tweaks in the Spectraview II software. Without this there was a very subtle green cast, especially in the mid-tone grays.

Just curious if this is OK, or for some reason a not a good idea.  (is it typical?) I know quite a few of you are running the NEC displays, so much more experience with them.

Really like it now that I've got it setup.
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howardm
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« Reply #1 on: May 11, 2011, 10:04:57 PM »
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let the display burn-in for a 100 hours before trying to do/calibrate critical work.  The CCFL tubes will mellow out a bit.

On my 241, I did end up setting specific x/y coordinates.
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Schewe
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« Reply #2 on: May 11, 2011, 10:58:40 PM »
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I agree with the burn in...and I don't dispute the 100 hours (although I didn't wait that long with my PA241W).

Also, there are some important things to check in the SpectraView software & Prefs; you want the option in the Prefs to average low luminance measurements, you want the highest quality (52 steps) in the Calibration and Profile option, you alwso want Best grayscale color tracking and you prolly want the option to do Extended luminance stabilization time, you also prolly want the Factory measurements in the source for color chromaticities. I presume you have selected the target settings for Photo Editing; D65, Gamma 2.2, luminosity 140 and contrast ratio Monitor Default? You may end up wanting to adjust the contrast ratio to lower it depending on what display you are coming from. What hardware are you using as the measurement device?
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Czornyj
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« Reply #3 on: May 12, 2011, 12:57:55 AM »
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What color sensor was used for calibration? I usually saw green cast after D65 calibration done with regular i1 colorimeter.

As for Prefs - highest quality (52 steps), best grayscale color tracking and extended luminance stabilzation time work you're calibrating the display with a colorimeter, and I'm not sure if they're necessarily such a good idea when a spectrophotometer (i1pro, ColorMunki) is used.

I've also heard that it's good to let the display burn-in for a couple of hours, with the whole screen set to white if possible (it has something to do with liquid crystal).
« Last Edit: May 12, 2011, 01:05:06 AM by Czornyj » Logged

Marcin Kałuża
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« Reply #4 on: May 12, 2011, 03:31:16 AM »
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Hi Wayne, I just set up my PA271W and are experiencing the same colour cast as you.
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Wayne Fox
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« Reply #5 on: May 12, 2011, 05:51:43 PM »
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Thanks for all the good advice.  The device is the included i1 display. (I assume it's just an i1 with NEC printed on it).  I haven't really looked into spectravsion II much, just did the basic steps, but the manual tweak has it pretty good (a little better than my 30" apple). Sounds like the best plan is to give the thing some time to burn in, then revisit the calibration and make sure I'm doing it right.  After it burns in, I'll check out some things (especially some of the details from Jeff, thx) just to make sure I'm doing it right.

« Last Edit: May 12, 2011, 10:24:22 PM by Wayne Fox » Logged

Alan Goldhammer
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« Reply #6 on: May 12, 2011, 07:07:23 PM »
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On the contrast the default for the monitor is much higher than you can achieve on an inkjet print.  You might dial this down to 350:1 for calibration purposes. 
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howardm
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« Reply #7 on: May 12, 2011, 08:54:09 PM »
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yes, you'll want to lower the contrast.  I think mine is something like .35 black
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aaronchan
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« Reply #8 on: May 12, 2011, 10:44:13 PM »
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"Your" i1d2 is not just a printed NEC oem version. NEC has actually modified the filter for their specific reason to optimized the result with their monitor. but under the earlier report from Ethan, these sensor will NOT do a good job on other monitors.
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Czornyj
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« Reply #9 on: May 13, 2011, 09:41:20 AM »
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On the contrast the default for the monitor is much higher than you can achieve on an inkjet print.  You might dial this down to 350:1 for calibration purposes.
yes, you'll want to lower the contrast.  I think mine is something like .35 black

I wouldn't make a general rule here, the perceived contrast can be substantially lowered by a light flare on the displays diffuser. I've used the basICColor DISCUS to make few measurements from the distance in various ambient light conditions, and in a bright enviroment the contrast ratio was only ~150:1, while the contact measurement was showing >500:1 and more.
« Last Edit: May 13, 2011, 02:19:40 PM by Czornyj » Logged

Marcin Kałuża
Wayne Fox
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« Reply #10 on: May 14, 2011, 02:28:22 PM »
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"Your" i1d2 is not just a printed NEC oem version. NEC has actually modified the filter for their specific reason to optimized the result with their monitor. but under the earlier report from Ethan, these sensor will NOT do a good job on other monitors.
Found that out.  Used it to calibrate the apple and it was horrible. 
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Jeff Kott
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« Reply #11 on: July 17, 2011, 09:33:44 PM »
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let the display burn-in for a 100 hours before trying to do/calibrate critical work.  The CCFL tubes will mellow out a bit.



I understand that the CCFL tubes may "mellow" after some number of hours of use, but I don't understand why you can't get a reasonably close calibration before that (and then not be surprised if the monitor drifts from that initial calibration as the tubes "mellow").

I just got a new NEC PA 241W with the Spectraview II software and NEC branded calibration puck. I plugged the monitor in and calibrated it and the screen has a greenish color cast. I spent a couple of hours researching this issue on the web and found this thread (which I had read previously) and made all the suggested tweaks to the software suggested by Jeff Schewe. I did another calibration and the monitor still has a greenish cast.

Previously, I was using an Eizo CG21 calibrated with ColorEyes DisplayPro and a DPT-94 and it looked great compared to the new PA 241W. I uninstalled ColorEyes DisplayPro just to make sure there would be no conflict with the Spectraview II software.

I know I shouldn't expect two different monitors using two different software packages and two different calibration instruments to look the same, but the thing is that whites in my prints printed on my Epson 4900 through Imageprint using IP profiles look white on the print and they looked white on my Eizo, but when I look at the printed image in Photoshop on my new PA 241W, the whites have a greenish tint (after making J. Schewe's suggested tweaks to the Spectraview software and recalibrating). There's no way I can do accurate color correction using this monitor.

BTW, I just checked and the white I'm referring to in my image has RGB values of 240,240,239 in Photoshop, but looks green on my monitor.

It just doesn't seem to me that this problem is going to slowly go away by itself after I let the monitor burn in for 100 hours.

Any help would be appreciated.
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digitaldog
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« Reply #12 on: July 18, 2011, 08:34:02 AM »
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BTW, I just checked and the white I'm referring to in my image has RGB values of 240,240,239 in Photoshop, but looks green on my monitor.

You have to adjust the white point using x/y custom values. See: http://www.luminous-landscape.com/forum/index.php?topic=55782.new#lastPost:

When people report their display is too green/magenta, the fix can be zooming in on the central white point of the CIE xy diagram in the SpectraView software. It will give you a better idea of how changing the x and y values will affect the white point. If the screen is too green, you‘ll want to move the white point down and to the right (vise versa for magenta). Make tiny adjustments (i.e. 0.002) and recalibrate. Understand that this only works if the calibration software allows you to enter specific CIE xy values.
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Andrew Rodney
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tony22
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« Reply #13 on: July 18, 2011, 12:05:01 PM »
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Andrew, I'm stepping in because I'm curious. Is this something that has been commonly observed with the NEC PA series?
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Jeff Kott
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« Reply #14 on: July 18, 2011, 12:10:37 PM »
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Andrew, I'm stepping in because I'm curious. Is this something that has been commonly observed with the NEC PA series?

And one other question - is the discrepancy in white point values caused by sample variation in the NEC branded calibration instrument? If not, what is the cause?
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Czornyj
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« Reply #15 on: July 18, 2011, 12:12:28 PM »
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I just got a new NEC PA 241W with the Spectraview II software and NEC branded calibration puck. I plugged the monitor in and calibrated it and the screen has a greenish color cast.

And one other question - is the discrepancy in white point values caused by sample variation in the NEC branded calibration instrument? If not, what is the cause?
Try to calibrate the display to D65 without a sensor using NEC Multiprofiler software, and tell us if the green cast is still there.
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Marcin Kałuża
digitaldog
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« Reply #16 on: July 18, 2011, 12:13:16 PM »
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And one other question - is the discrepancy in white point values caused by sample variation in the NEC branded calibration instrument? If not, what is the cause?

Possible, but all displays and graphic systems they utilize are different or we wouldn’t have to calibrate them. Point is, you should be able to fix the issue by adjusting the WP with the provided tools.
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Andrew Rodney
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Jeff Kott
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« Reply #17 on: July 18, 2011, 12:15:26 PM »
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Try to calibrate the display to D65 without a sensor using NEC Multiprofiler software, and tell us if the green cast is still there.

Thanks for the suggestion - I'll try this tonight and post results later.
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Jeff Kott
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« Reply #18 on: July 18, 2011, 12:27:29 PM »
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Possible, but all displays and graphic systems they utilize are different or we wouldn’t have to calibrate them. Point is, you should be able to fix the issue by adjusting the WP with the provided tools.

I don't really understand what you're saying. The point of calibration is to get consistency. There are three variables, the monitor, the calibration software and the hardware calibration device.

Now, it's a given that the monitors have some sample variation and the colors will drift over time. That's why we calibrate them. There's no variation in the Spectraview II software so if when I calibrate using the NEC colorimeter my whites have a greenish cast, either I'm using the software incorrectly or the colorimeter is off.

One possibility is to adjust the white point using the x/y custom values until the whites look white - but then I'm really just using my eyeballs as the colorimeter. The other option would be to return the colorimeter until I get one that seems to work without having to change the white point by what looks good to my eye.

So, I'm wondering if the problem that a number of people have is just poor quality control with the NEC branded colorimeter. I never had this problem using ColorEyes Display Pro with my DPT-94.
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digitaldog
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« Reply #19 on: July 18, 2011, 12:30:53 PM »
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I don't really understand what you're saying. The point of calibration is to get consistency.

If that were true, there would only be one calibration target aim points. We’d always use them for that consistency. But its pretty clear that we have to specifically ask for a target for TRC gamma (not all that important), white point and luminance (very important) and if available, contrast ratio. The point of calibration is first and foremost to set the display conditions to an idealized behavior (for me and many others, to visually match a print next to that display). Then we want consistency in that behavior.
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One possibility is to adjust the white point using the x/y custom values until the whites look white - but then I'm really just using my eyeballs as the colorimeter.
Yup and that’s all fine if the goal is a visual match to the print. That’s what most of us are after.
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Andrew Rodney
Author “Color Management for Photographers”
http://digitaldog.net/
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