Calibration of Dell U2412M

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  • #28753

    Vincent
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    There’s a Dell_U2413_25Jul12.ccss file. Mine is U2412M, will that still be good? how do you see if it’s 3nm or 10nm?

    That is a GBLED (AdobeRGB + huge % of p3). Yours is a common WHite LED IPS sRGB only, MW showed your generic correcion (Whiet LED IPS).

    #28755

    Vincent
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    BTW you are adjusting the deviation of the barrel in the gun. But i1d3 gun is smart enough to know its deviation so if you provide “shape & distance” (CCSS) of the target, gun self aligns (software does, not device, but as an example).

    Non smart guns can only be corrected by measuring deviation then offset (CCMX). Smarts guns can be corrected this way too, all guns can. But you need a “laser pointer” (spectrophotometer like an i1Pro2) to correct the aim after firing a test shoot.

    Smart guns can be corrected in a distributed way (no laser pointer needed in YOUR side) , same correction for all, rely on self align based on firmware data for THAT particular target (spectral power distribution, CCSS data)

    • This reply was modified 2 weeks, 4 days ago by Vincent.

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    #28757

    Gil
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    There’s a Dell_U2413_25Jul12.ccss file. Mine is U2412M, will that still be good? how do you see if it’s 3nm or 10nm?

    That is a GBLED (AdobeRGB + huge % of p3). Yours is a common WHite LED IPS sRGB only, MW showed your generic correcion (Whiet LED IPS).

    Ok, so what is the exact file name I need? so many files there and I don’t know what to select. Nothing there states U2412M and the only thing that mentions “WHite LED” is Spectral: LCD White LED family (AC, LG, Samsung).

    I’ve done the banding test and I’m confused.

    Open in MS Paint, open in PS (assign sRGB colorspace if missing, IDNK your PS configuration, same for GIMP, neutral vertical bar banding is expected, color banding only if you use 3xTRC profiles)

    I opened the gradient image on PS (I use sRGB as working colour space), I opened IrfanView which is colour managed, and I opened windows photos, which is not colour managed.

    I have 3 monitors. Currently, the right monitor is the one I upload the calibration reports. Centre monitor was calibrated long time ago.

    Using IrfanView (colour managed) and Windows Photos (not colour managed) on the calibrated screen and non calibrated screen = no banding.

    Using photoshop – non calibrated screen = no banding. Calibrated screen – a clear sign of banding. Why is that? I thought the unmanaged image viewer will show banding.

    I made a screenshot comparing photoshop and windows photos – I hope you can see what I’m seeing in the screenshot.

    p.s. – are you Vincent Teoh? since I bought my LG CX last year, I follow HDTVTest on youtube and twitter. I want to learn how to calibrate this broken TV.

    • This reply was modified 2 weeks, 4 days ago by Gil.
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    #28760

    Vincent
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    There’s a Dell_U2413_25Jul12.ccss file. Mine is U2412M, will that still be good? how do you see if it’s 3nm or 10nm?

    That is a GBLED (AdobeRGB + huge % of p3). Yours is a common WHite LED IPS sRGB only, MW showed your generic correcion (Whiet LED IPS).

    Ok, so what is the exact file name I need? so many files there and I don’t know what to select. Nothing there states U2412M and the only thing that mentions “WHite LED” is Spectral: LCD White LED family (AC, LG, Samsung).

    yes, or user made CCSS 3nm for U2412M (not CCMX).

    I’ve done the banding test and I’m confused.

    Open in MS Paint, open in PS (assign sRGB colorspace if missing, IDNK your PS configuration, same for GIMP, neutral vertical bar banding is expected, color banding only if you use 3xTRC profiles)

    I opened the gradient image on PS (I use sRGB as working colour space), I opened IrfanView which is colour managed, and I opened windows photos, which is not colour managed.

    I have 3 monitors. Currently, the right monitor is the one I upload the calibration reports. Centre monitor was calibrated long time ago.

    Using IrfanView (colour managed) and Windows Photos (not colour managed) on the calibrated screen and non calibrated screen = no banding.

    = display profile = “supposed” image colorspace = sRGB, no color management transformations (source & destination match)

    Infranview color management seems to be off on preferences = no color management transformations (source & destination match)

    Using photoshop – non calibrated screen = no banding.

    = uncalibrated display profile = “supposed” image colorspace = sRGB, no color management transformations (source & destination match)

    Calibrated screen – a clear sign of banding. Why is that? I thought the unmanaged image viewer will show banding.

    = calibrated display profile != “supposed” image colorspace , color management transformations at limited precision. Blame Adobe PS.
    LR & C1 & ACR use dithering.

    p.s. – are you Vincent Teoh? since I bought my LG CX last year, I follow HDTVTest on youtube and twitter. I want to learn how to calibrate this broken TV.

    No

    #28761

    Vincent
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    Using single curve creates a profile that says “grey is perfectly neutral” (equal TRC curves). Hence color managed banding is fro limited precision correcting TRC between source (sRGB, 2.2, L*, 1.8…) and actual display TRC. “Colorless banding”.

    It does not need to be true, it’s a simplification to avoid issues like that in PS. In HW cal monitor like Eizo profiles made after HW cal are usually that way (1TRC) since after calibration behavior is expected to be close to excellence on grey neutrality.
    If after calibration your U2412M is so well behaved that a single curve + mtx validates OK, use it for PS if banding bothers you. “simplified profile” matches display = you can use it.

    • This reply was modified 2 weeks, 4 days ago by Vincent.
    #28763

    Gil
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    “supposed” image colorspace = sRGB

    I opened in photoshop and saved it with sRGB.

    Infranview color management seems to be off on preferences = no color management transformations (source & destination match)

    You are correct, it was off. I enabled it and set it to use “current monitor profile”. Banding is now visible! (screenshot)

    By current, I don’t know if it means the main monitor (center, yet to be profiled) or the monitor on which the image is being viewed. I don’t know where the .icm file is saved in Windows. I’ll look it up, but should I set IrfanView to use my monitor profile?

    = calibrated display profile != “supposed” image colorspace , color management transformations at limited precision. Blame Adobe PS.
    LR & C1 & ACR use dithering.

    If my monitor is profiled and is capable of 97% of sRGB and photoshop workspace is sRGB, there shouldn’t be colour management transformation. So I’m not really clear what’s happening here.

    Reading your last post:

    1. Based on the report of my calibration on the right monitor, you mean that if the report (profile behaviour on my monitor) is good, I can set photoshop workspace to use the monitor’s colour profile instead of sRGB?
    2. OR instead of setting PS to the monitor profile you mean set DispcalGUI to Profile Type: Single curve + matrix, instead of XYZLUT? (What should be the Tetchart size?)
    • This reply was modified 2 weeks, 4 days ago by Gil.
    • This reply was modified 2 weeks, 4 days ago by Gil.
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    #28767

    Vincent
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    “supposed” image colorspace = sRGB

    I opened in photoshop and saved it with sRGB.

    Infranview color management seems to be off on preferences = no color management transformations (source & destination match)

    You are correct, it was off. I enabled it and set it to use “current monitor profile”. Banding is now visible! (screenshot)

    By current, I don’t know if it means the main monitor (center, yet to be profiled) or the monitor on which the image is being viewed. I don’t know where the .icm file is saved in Windows. I’ll look it up, but should I set IrfanView to use my monitor profile?

    It should be the monitor on which the image is being viewed, auto. It is not about folders, it is about associate a display with a profile on OS settings. Anyway: C:\Windows\System32\spool\drivers\color that includes display profiles, printer profiles and working colospace profiles.

    = calibrated display profile != “supposed” image colorspace , color management transformations at limited precision. Blame Adobe PS.
    LR & C1 & ACR use dithering.

    If my monitor is profiled and is capable of 97% of sRGB and photoshop workspace is sRGB, there shouldn’t be colour management transformation. So I’m not really clear what’s happening here.

    That is not correct. Unless source profile and destination profile are EXACTLY the same there is always color management: gamut boundaries, in gamut volume and TRC.
    And if they are equal there is color management too, but is a null transfromation (identity).

    Reading your last post:

    1. Based on the report of my calibration on the right monitor, you mean that if the report (profile behaviour on my monitor) is good, I can set photoshop workspace to use the monitor’s colour profile instead of sRGB?
    1. no, never (or almost 99.9999% confidence never do that). I’m saying to build a simpler profiler from scratch with Displaycal, maybe reusing previous grey calibration that seems good (but that woul lead to more questings and reconfiguring whole calibration tab, so it may be easier for you redo from scratch single curve matrix profile with Black Point Compensation BPC=ON).
    1. OR instead of setting PS to the monitor profile you mean set DispcalGUI to Profile Type: Single curve + matrix, instead of XYZLUT? (What should be the Tetchart size?)

    Yes, choose whatever chart you want. Small 1xx patches chart for LUT profiles may track actual TRC (brightness across grayscale) better, I’ll use that (175) for a matrix profile.

    • This reply was modified 2 weeks, 4 days ago by Vincent.
    #28769

    Gil
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    Used single curve + matrix.

    It doesn’t seem to track gamma better than the previous profiling I did with XYZLUT+matrix.

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    #28774

    Vincent
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    It can’t. It’s simplified = true neutral grey (1TRC) + infinite contrast (BPC).

    #28775

    Gil
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    p.s. – when I re-profile, does Dispcal remove the previous profile or do I need to do it manually? I’m just trying to be sure if the previous calibration doesn’t affect the newer calibration.

    #28776

    Vincent
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    p.s. – when I re-profile, does Dispcal remove the previous profile or do I need to do it manually? I’m just trying to be sure if the previous calibration doesn’t affect the newer calibration.

    It does not remove old ICM file. Also it does not matter.

    Displaycal clears GPU calibration (unless instructed to do not do it), makes a new one, apply it, then measure after calibratio behavior and stores it in profile (and embeds GPU calibration in VCGT tag inside profile).
    Then ask user to assign it as default display profile in OS. This last past is what matters.

    • This reply was modified 2 weeks, 4 days ago by Vincent.
    #28778

    Gil
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    It can’t. It’s simplified = true neutral grey (1TRC) + infinite contrast (BPC).

    But looking at the report, there’s a gap between what’s expected to what’s measured. So I guess I don’t know how to read the graph correctly, or there’s something else I don’t quite understand.

    Comparing the report between XYUZLUT and the single curve, the XYZLUT seems better tracking. What don’t I understand?

    #28779

    Gil
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    Banding still happens using the gradient test file with photoshop, using the single curve + matrix, and with IrfanView.

    With unmanaged colour apps like windows photos, no banding. I still don’t get it.

    #28781

    Vincent
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    It can’t. It’s simplified = true neutral grey (1TRC) + infinite contrast (BPC).

    But looking at the report, there’s a gap between what’s expected to what’s measured. So I guess I don’t know how to read the graph correctly, or there’s something else I don’t quite understand.

    Comparing the report between XYUZLUT and the single curve, the XYZLUT seems better tracking. What don’t I understand?

    Single curve matrix is an idealized profile. It tracks worse actual monitor behvior, but rounding errors due to lower precision color management are less annoying. Banding is there, but is colorless (unles your intel iGPU or nvidia card cannot calibrate bandless).
    Also GPU aceleration to “basic” causes less issues in PS

    With unmanaged colour apps like windows photos, no banding. I still don’t get it.

    You cannot map 256 tones with some arbitrary TRC (image) to other 256 tones TRC (display) without loosing some values and repeating others, unless you use dither.
    Same for colorspace volume. It’s unavoidable unless you use dither or widen bitdepth end to end.

    • This reply was modified 2 weeks, 3 days ago by Vincent.
    #28784

    Gil
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    So what should I do?

    You cannot map 256 tones with some arbitrary TRC (image) to other 256 tones TRC (display) without loosing some values and repeating others, unless you use dither.

    I know what dithering is, I don’t know what you mean by arbitrary TRC. I think there’s a gap in my understanding, which you gracefully try to explain to me, but I think I don’t understand your explanation. It’s not your fault. I think the way I learn is by visualizing, and the explanations simply don’t make sense to me.

    I have an image saved in sRGB profile, doesn’t seem arbitrary to me at all. I have a monitor profiled in a manner that covers about 97% of sRGB. I load a greyscale image and I get banding. How is this mechanism work? This monitor is good enough and shouldn’t present banding. If an unprofiled monitor can present this image without banding, why a profiled monitor is worse? What’s the point of profiling if I get worse results?

    So what should I do now? I don’t trust my calibration is correct or I’m getting my monitor to its peak performance.

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