displaycal overcorrecting green channel on 99% p3 monitor

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  • #35629

    NoVoicemail
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    I have an older lg ultrafine 22″ 4k monitor with native white point 8000k and 99% p3 gamut. Using the 2016 macbook retina 1nm 99% p3 correction and calibrating to D65 2.2 gamma, displaycal always over corrects the green channel and leaves me with a reddish hue(verification shows ok). Other corrections i’ve tried include p3 family and user 3.3nm ccss corrections all with similar results, its just way too red. Using visual white point editor I can get much closer to neutral by correcting mostly blue channel and the green channel very slightly. I just feel this is not very precise. what else can I try? do i need a custom correction? thank you

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    #35632

    NoVoicemail
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    i added two VCGT graphs

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    #35635

    Vincent
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    If you are using macOS you may want another profile type, simpler (defaults).

    Regarding your actual question, same as here:

    Reply To: Calibration seems too magenta

    if you get the same pinkinsh tint then may be 32ud99 uses other backlight (try to rent an spepctrophotometer and share CCSS with community) or that colorimeter firmware data does not mach actual colorimeter response (use visual whitepoint editor or rent an spectrophotometer to make a CCMX matrix) or your own visual system is not very close to std observer (use visual whitepoint editor).

    1st one may need a custom CCSS (unlikely, but reorder macbookretina CCSS to have WRGB order in spectral data samples, i did reorder mine years ago, maybe it is no longer needed, I have not imported default CCSS pack since then)
    2nd one will be needed if colorimeter firmware has no good QC (2dE to a reference 1nm is expected)
    3rd one is unavoidable, statistics work this way. Use visual whitepoint and remember to use relative white popint intents when making LUT3D.

    #35674

    NoVoicemail
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    reorder macbookretina CCSS to have WRGB order in spectral data samples

    curious what reordering the spectral sample effect would be? currently the order is RGBW

    #35679

    Vincent
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    Test

    #35681

    NoVoicemail
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    as far as I can tell the results of WRGB and RGBW ccss are identical. what effect does rearranging spectral order have normally? I was not able to find any explanation on argyll website

    #35682

    NoVoicemail
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    [V1.3.5 -> V1.3.6] 19th March 2012

    Changed ccxxmake to create default .ccss with just  RGBW, and not to weight W. This may give better matching. Made corresponding change to CCMX, giving the white patch 1/4 weighting of sum of all other patches.

    Theres seem to be no mention of WRGB in the argyll changelog

    #35683

    Vincent
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    Default order is WRGB for all tools, community CCSS and EDR from Xrite.

    To test if current Argyll is able to auto order them dump RGB to XYZ matrices with WRGB and RGBW (-D3 in some argyll tool that uses colorimeter)

    • This reply was modified 3 days, 7 hours ago by Vincent.
    #35685

    NoVoicemail
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    X-rite claims on  this page all iMac 4k/5k and Apple’s LG Ultrafine 4k/5k are RG Phosphor.

    As of late 2015, Apple has changed the technology type in the Retina 5K, 27″ and Retina 4K, 21.5″ iMacs to an RG Phosphor backlight.

    X-rite explicitly states only macbooks are PFS phosphor. Whats interesting is most of the community ccss for iMacs have plots that look close to the bundled 1nm PFS correction rather than the bundled RG corrections. Yet I was able to get better results using the bundled RG corrections. Ive also tested with i1Profiler and had similar bad results with PFS but decent results with RG. This is very odd

    • This reply was modified 3 days, 6 hours ago by NoVoicemail.
    #35687

    Vincent
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    i1Profiler has an EDR for Panasonic VXX, bundled in DisplayCAL too (it comes from Xrite EDR) with has a native green that does not cover P3 green. That is Xrite’s WLED PFS… but ther are at least 3 flavors. That one for 95% P3 gaming/multimedia, exactly P3 for Apple and AdobeRGB and P3 for newer photo displays.
    Xrite has n EDR for that last one but it is not bundled in i1profiler.

    Xrite EDR pack in i1Profiler/ccProfiler is very limited and does not have all EDRs that Xrite has created for other vendors (or thta has been created with Xrite license).

    So Xrite has no EDR that matches macbook’s WLED PFS with exactly P3 red and P3 green. So it is uselesss whatever they say about apple displays, or whatever you test on i1Profiler.
    You may try to override Xrite EDR (panasonic VVX) with data from DisplayCAL 1nm CCSS made for Apple P3 (reorder so it s WRGB as all other EDR)

    #35688

    NoVoicemail
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    what im wondering is displaycal’s bundled RG phosphor ccss gives better results than the bundled PFS 2016 retina macbook 99% p3 ccss which lines up with x-rites claim of the panel being RG phosphor.  Whats strange is most of the community 3nm iMac ccss looks similar to PFS 2016 retina macbook 99% p3 ccss which seems to indicate the panel is actually PFS not RG.

    #35693

    Vincent
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    No, the proper one for P3 mac is WLED PFS for mac, WRGB, bundled with DisplayCAL. Period. spectral power distribution data is the key.

    If you get a white different form what you expect may be because your vision being an statistical outlier of std observer cie 1931 2degree (given the spiky nature or WLED PFS red)

    or

    your i1d3 firmware data is not very accurate (it does not match actual colorimeterfilter response). This is somehow expected that a CCSS corrected measurement falls within 2dE radius from true accurate CIE 1931 2degree measured with a true reference device like a jeti or a CR.

    Both reasons may contribute to overall result… and they are corrected the same way: visual whitepoint editor… or if the later id teh bigger contribution, matrix correcting your colorimeter to a high res reference device like a JETI or CR but since it be cost prohibitive use visual approach.

    Using a wrong CCSS because you are an statistical outlier to the std observer mean or because i1d3 firmware is not accurate is useless because it is like shooting in the dark. Visual white point editor will give you better results since it is a guided process from numerical D65 match to percieved D65.
    If using some kind of visual match, remember to do not make LUT3D with absolute colorimetric.

    #35697

    NoVoicemail
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    Thanks for your reply. X-rite already correctly indicates that macbooks are PFS just as you are stating, where X-xrite differs is they indicate iMacs use a different backlight technology than macbooks. This is the where the confusion lies. For an i1profiler user, wouldnt iMacs get better results using the PFS edr (panasonic vxx) that xrite already recommends for macbooks? Xrite is suggesting, on iMacs only, their RG phosphor edr, which looks nothing like the PFS (panasonic vxx) edr, gets better results than the PFS edr (panasonic vxx) which is much closer to displaycal’s PFS 99% macbook ccss.

    • This reply was modified 3 days, 2 hours ago by NoVoicemail.
    • This reply was modified 3 days, 2 hours ago by NoVoicemail.
    #35701

    Vincent
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    Plot each all CCSS for WLED PFS and you’ll see. The correct one for apple is the one labeled macbook retina.

    Xrite’s Panasonic VVX only will give you good results if your colorimeter is almost a match for CIE 1931 2degree in those green wavelengths (where actual macbook and that CCSS differ from each other) …. because there is nothing to correct. All other scenarios will give an error, worse as colorimeter difts further form std observer.
    That is the reason to use CCSS, to avoid the need of a perfect colorimeter.

    IDNK if i1Profiler has some kind of assited visual whiet point editor. If not you’ll need DIsplayCAL.
    Another option is to forge a panasonic vxx EDR with macbook retina WRGB spectral data,  the replace the original one (with backup) in Xrite correction folder, then use i1Profiler. Read Midas’ CS2731 thread.

    • This reply was modified 3 days, 2 hours ago by Vincent.
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