Help with DCI P3 coverage on new display

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  • #25142

    andrewted
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    Hi, I have tried for several days now to get my monitor to calibrate at least near the advertised DCI P3 coverage but with bad results, and I am at a loss now on what might be the issue here.

    My monitor is an LG 27GL850 using the nano IPS panel and it is supposed to be at a DCI P3 coverage of 98%

    I am trying to calibrate the monitor with a Colormunki using a gamma 2.2 profile, whitepoint around 120 cd/m2 and at around 6500k of rgb.

    I am using the PFS Phosphor IPS 94% from Panasonic for the colorimeter correction, I also tried other corrections but all of them gives the same results.

    The issue is I can only reach around 91% of DCI P3 gamut coverage wtih a Gamut Volume of around 98%. I understand that I might not get close to the advised 98% but I have seen several other cases of this monitor calibrated in DisplayCal and in all cases users were reaching around 95-96% gamut coverage at least.

    What might be the issue here? Is it the panel itself which is not acting properly or just a bad one, or it might be my colorimeter that is acting up considering it’s around 5-6 yrs old, is there some other setting I have to use to improve the coverage?

    Any help will be greatly appreciated

    #25145

    AstralStorm
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    This is very likely not a PFS screen. It is likely the case of LG RG panel with the native DCI-P3 primary LED color setup. Try using Samsung Quantum LED profile which has the same primaries and standard white mixing behavior. (unlike WOLEDs)

    It is still not enough though, but should produce much better results.

    • This reply was modified 1 week, 5 days ago by AstralStorm.
    #25149

    Vincent
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    Shared by Florian some time ago. You’ll need to code 2D graph into CCSS. You can set White =R+G+B in an spreadsheet:

    Which Correction is proper for LG TV? (2019 Nanocell)

    What is LG’s Nano Cell Technology?

    Looks close the SPD of an WOLED but inorganic, and without W of course.

    #25152

    AstralStorm
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    If calibrating at high brightness or high color gain/saturation, e.g. for HDR, you might also want to use CIE 2012 observer as I found only this one produces accurate results in that case. (Making dark part of display slightly cold though.)

    #25164

    S Simeonov
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    So in short which correction should we use for nano IPS displays?

    #25165

    Vincent
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    So in short which correction should we use for nano IPS displays?

    There could be several flavors, but one is the YAG phosphor suggested by Florian and explained in that link.

    Unfortunately AFAIK there is no user made CCSS, so if you wish to use an spectral correction for YAG phosphor backlight you’ll have to code it from 2D plot. Not extremely difficult at 10nm step… but time costly.

    PS: If somebody do it, sharing it with community would be kind since some unexperienced users may find cumbersome making it from scratch.

    • This reply was modified 1 week, 5 days ago by Vincent.
    #25167

    S Simeonov
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    So in short which correction should we use for nano IPS displays?

    There could be several flavors, but one is the YAG phosphor suggested by Florian and explained in that link.

    Unfortunately AFAIK there is no user made CCSS, so if you wish to use an spectral correction for YAG phosphor backlight you’ll have to code it from 2D plot. Not extremely difficult at 10nm step… but time costly.

    PS: If somebody do it, sharing it with community would be kind since some unexperienced users may find cumbersome making it from scratch.

    The chance for somebody to code is very slim…

    #25168

    Vincent
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    So in short which correction should we use for nano IPS displays?

    There could be several flavors, but one is the YAG phosphor suggested by Florian and explained in that link.

    Unfortunately AFAIK there is no user made CCSS, so if you wish to use an spectral correction for YAG phosphor backlight you’ll have to code it from 2D plot. Not extremely difficult at 10nm step… but time costly.

    PS: If somebody do it, sharing it with community would be kind since some unexperienced users may find cumbersome making it from scratch.

    The chance for somebody to code is very slim…

    I did not choose the proper word. My mistake. I meant to translate this 2D graph (in the link) to a spreadsheet, 1 row for each channel, 1 white as the sum of RGB, 10nm interval:

    Time consuming yes, buy you can do it even with Paint.

    Once in spreadsheet,  just use a 10n CCSS as template and paste new spectral data from spreadsheet.

    So no “coding” (programming), just “translate to spreadsheet numbers” a 2D plot in a JPG.

    #25169

    Vincent
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    Shape looks like RGB channels in WOLED but I did not plot it and compare RGB SPD from an WOLED scaled to nm & height.
    *If they were a close match* (and this is a big if) “cooking” a CCSS for those YAG phosphors would be even easier, just get W=R+G+B and copy back to an WOLED CCSS template.

    #25170

    S Simeonov
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    Shape looks like RGB channels in WOLED but I did not plot it and compare RGB SPD from an WOLED scaled to nm & height.
    *If they were a close match* (and this is a big if) “cooking” a CCSS for those YAG phosphors would be even easier, just get W=R+G+B and copy back to an WOLED CCSS template.

    It sounds pretty complicated to me. 🙁

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