Hi,

We are profiling some PA243W NEC LCD monitors which we purchased in 2017.

The monitors are connected to our Linux workstations via displayport. We are using Lightspace with a Lightspace Supplied X-Rite i1 with the patch generation java tool with lightspace set up for the following settings:

* Calibration Settings = Generic CMF
* Average Low Light Measurements = True
* Enable Visible Feedback = True
* Luminance Units Max = 104
* Set Color Standard Target = Rec709
* Target Gamma 2.4

We've turned off eco mode, sharpening and are not using black levels

we're following the idiots guide to manual calibration and using a primaries quick profile to assess the monitor.

We believe we're getting: Reasonable Grey Scale Delta-E, Not great RGB separation and a Gamut coverage maximum of 96.3%.

Please see the following link:

https://drive.google.com/file/d/12SDSvxZT3HJWORAEg0fQvToJtpo8jwVX/view?usp=sharing

Please could you recommend any steps we should take to improve our result, or is this the best we are likely to see?

Best wishes,
George

Hi George - you'll need to show the Before profile too.
Difficult to make any suggestions form just the post results.

But, The probe should use a preset that best matches the backlight type f the NEC.
(You will need to ask NEC what it is for your exact display, but likely RG Phosphor (GB-LED) or PSF Phosphor.)

Also, enable visible feedback is not relevant - that is just to show the user when the probe is doing something.
And the Luminance Units Max is only required for individual Manual Measurements.
That is also true of Set Colour Standard Target and Gamma Target.
None of those settings are used when performing an automated profile, as they are just for Manual Measure use.
(The targets are set when making the LUT within Convert Colour Space.)

Steve

Thank you for the information and your quick response Steve.

Our NEC rep is away right now but the following link compares the NEC monitors that we use here and indicates that the PA243W uses WLED type backlight.

https://www.displayspecifications.com/en/comparison/84f0b6034

As such we've done profiles using CMF and White LED as a comparison.

We took another PA243W monitor and factory reset it to perform a suitable pre profiles.

We ran 2 X pre profiles - Rec709/ Gamma 2.4/Primaries + Secondaries

1) CMF - Factory reset
2) WLED - Factory reset - Gamma 2.4

Then we ran 4 X post profiles: Rec709/ Gamma 2.4/Primaries + Secondaries

1) CMF - pushing blue causes CYAN to land outside gamut
2) CMF - reducing blue to get cyan to land within the gamut
3) WLED - pushing blue coordinates futher results cyan landing outside of gamut
4) WLED- used less extreme blue - keeps cyan inside rec709 target

All 6 reports can be found in the google drive folder below.

https://drive.google.com/drive/folders/1khDbjC--M_n3RmazswqvDcat8tAkWz2h?usp=sharing

Please can you let us know what you think about the results and if we can improve the gamut coverage further?

Best wishes,
George

WLED is a generic term, and often DOESN'T mean While LED.
As said, they are probably RG Phosphor (GB-LED) or PSF Phosphor.
But only NEC can tell you.

As for the calibration/profiles, I really do not understand what you mean by 'pushing blue'?
That is not a term I am familiar with, as you cannot 'push' colours when calibrating.
The maximum gamut of the display is the maximum it can do.
You cannot extend it.

Your 'Pre Calibration' profiles show the display is very low in blue before calibration.
(Assuming you have disables any/all internal displays calibration.)
And if so, there is nothing you can do about that.

However, your Post Calibration profiles show more blue.
And they show a higher peak luma than the Pre profiles.
(And a higher black.)

That is just not possible, so something is very wrong somewhere...
And I have no idea what...
You need to check and verify what you are actually doing, as it makes no sense.

Steve

Thanks for your quick response and clarification about WLED.

If I can just verify our steps:

1) Set Rec709 and Gamma 2.4
2) Brightness and contrast cal check
3) Set Peakwhite
4) Brightness and contrast cal recheck
5) Check Greyscale
6) Set Gamut and Colour

It's at this stage that we using the following monitor OSD to set red green and blue coordinates for rec709.

When I say pushing blue - I mean trying to use the measure interface to set the primary of blue. Please see below.

https://ibb.co/h90hMxJ

Why, when you have a monitor with internal 3D LUT capability are you just playing with the manual controls?
Sorry, that makes no sense.

Have you not read the '3D LUT User Guide' on the website. and followed that?

Steve

Hi Steve,

NEC have confirmed that these PA243W use GB-r LED which should be the same as RG Phosphor (GB-LED)

We've been following the manual calibration as we believed adding a LUT would further the reduce the gamut coverage.

We're now following the 3D LUT calibration Guide and will let you know how we get on.

Many thanks again,

George

Hi Steve,

We've tried the 3D LUT Calibration Workflow you recommended for the same monitor.

STEPS TAKEN

1) Warm up probe and display which is connected to the Linux workstation via Display Port or DVI.
2) In Lightspace set max brightness to 104Nits and calibration settings to RG Phosphor under options.
3) Factory reset the monitor
4) Change the monitor preset to BT-Rec709
5) Set Gamma to 2.4 on monitor
6) Switch Off uniformity on the monitor
7) Run Pre Profile Primaries and Secondary Profile & generate report
8) Run Pre Profile Gamma 100% with Secondaries Profile & generate report
9) Adjust the brightness to 104Nits (but do not move the White point)
10) Check the brightness and contrast using provided charts
11) Run a 10 side display characterisation profile & generate report
12) Use the display characterisation to generate a colorspace.
13) Apply the colorspace & run a post primaries & secondaries profile & gen report
14) Apply the colorspace &run a post gamut100%+Secondaries profile & gen report
15) Apply the colorspace & run a post profile with gamut 75% & generate report

REPORTS AND BCS FILES

Google Drive with Reports and BCS Files
https://drive.google.com/drive/folders/1T9An2s8d_8de1fe5qmubN-hBefnkiZzI?usp=sharing

Lucidchart Link with Reports
https://www.lucidchart.com/documents/view/0fedd25a-8258-4cff-865e-f2b5d12ae3e0/2

* In addition to the pre/post reports there is also a report for the 10 side display characterization that may or may not be useful.

GAMUT COVERAGE RESULT: PRIMARY AND SECONDARY VS GAMUT SWEEP QUICK PROFILES

We chose to run gamut sweep as well as primary and secondary quick profiles for both pre and post profiles as we're getting very different results for gamut coverage between them. In both cases the primaries and secondaries produced considerably worse results for gamut coverage compared to the gamut sweep quick profiles.

We thought this could be because primary and secondaries are measuring at the 7 specific points only. If the monitor is unable to display one or more of those points it'll quickly drag down the gamut coverage results.

Is that a correct interpretation?

In our quest for better gamut coverage should we be using one profile type over another?

GAMUT COVERAGE: GAMUT SWEEP 75% VS GAMUT SWEEP 100% POST PROFILES

We got quite different results for gamut coverage for the different gamut sweep quick profiles. Gamut sweep 75% resulted in a higher gamut coverage of 99.4% compared to the Gamut 100% and secondaries quick profile, which was recorded 97.1% coverage. The guide explains that "Gamut Sweeps maintain the same 'colour' level (100%, or 75%), and change the saturation level in progressive steps."

Please could you explain what is meant by "'colour' levels" here?

Please could you tell us if one gamut sweep is better than the other or if they both should be used to get a better understanding of the the display?

GAMUT COVERAGE: PRE VS POST RESULTS

We created a LUT within lightspace and we applied this for our post profiles to perform LUT verification. The gamut coverage with the LUT applied is pretty similar to the pre profiles, without the LUT applied.

* Primaries and Secondaries - Pre 88.8% - Post - 89.1%
* Gamut Sweep 100% + Secondaries - 97.2%, Post - 97.1%
* Gamut Sweep 75% Pre - N/A, Post - 99.4%

How should we interpret the similarities between the gamut coverage results between pre and post results for same type of profile? Also how should we read the differences between the post results for gamut coverage for the different types of profiles ? The guide recommends "Select the desired 'Quick Profile type', such as a Gamut Sweep', or 'Memory Colours' which will verify the LUT Calibration." Should we not be using primaries and secondaries for LUT verification at all?

Many thanks in advance,
George

Sorry, but nothing seems to make logical sense.
I can't follow your steps, based on the instructions you should be following in the User Guides.
You seem to be doing things very differently?

I'm travelling at the moment, so can't look deeper into your data.
Hopefully, someone else can help.

I'll have a better look as soon as I have time.

Steve