"As Measured" question…

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  • #4267

    Steve Smith
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    Hi there.

    OK, so I have a question that’s been bothering me since the beginning… I’ve already asked a similar question, but I don’t think I worded it right.

    So, If I use your ‘Interactive Measuring tool’ to measure the RGB levels and white point, then adjust my monitor to reach the targets (6500K\120 ) – What happens during the calibration if I leave the targets inputted vs. switching to ‘As Measured.  (What is the exact difference in the way it will calculate)

    The reason I ask this question is because it seems that the interactive tool only measures the RGB levels at one point along the grayscale…But what happens if the monitor isn’t linear? Wouldn’t I, in most cases , leave the values inputted so that the calibration will self adjust along the gamma curve to maintain the targets? … If I leave it on ‘as measured’ aren’t I only hitting the target in one point along the gray-scale?

    I want to know how to set this control for optimal results As measured or leave values inputted.    (In a situation where the monitor is far from linear.

    Thanks for your answer. 🙂  (And patience with me!)

    #4283

    Florian Höch
    Administrator
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    What happens during the calibration if I leave the targets inputted vs. switching to ‘As Measured. (What is the exact difference in the way it will calculate)

    The difference between white point “As measured” vs a specific target is simply that “As measured” will use the measured white as target.

    The reason I ask this question is because it seems that the interactive tool only measures the RGB levels at one point along the grayscale

    Depends if you have tone curve set to “As measured” or not. “As measured” will essentially skip 1D calibration and leave any correction to a later point (i.e. when the profile is used). Any other specific tone curve setting will make the calibration match the white point over the whole grayscale.

    #4291

    Steve Smith
    Participant
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    So then are these two statements correct?

    I should choose ‘as measured’ for the white point (When I am able to pre-adjust it at the hardware level  first).

    I should choose ‘Tone Curve = xx’ (When I cannot make any pre-gamma adjustments at the hardware level first)

    Does the same apply for the ‘White Level’?

    Do  I have this right?

    • This reply was modified 7 years, 6 months ago by Steve Smith.
    #4305

    Florian Höch
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    I should choose ‘as measured’ for the white point (When I am able to pre-adjust it at the hardware level first).

    White point “as measured” is useful when you have already adjusted it before, and thus want to skip the guided adjustment step this time around.

    I should choose ‘Tone Curve = xx’ (When I cannot make any pre-gamma adjustments at the hardware level first)

    The choice here basically comes down to “do I need 1D calibration curves”, i.e. for applications that don’t support color management (e.g. the Windows desktop and such, on Mac OS X the desktop is color managed), or as a way to pre-linearize a display (which can aid profiling with fewer patches).

    Does the same apply for the ‘White Level’?

    Choosing a preset white level you’d do for the same reason as a preset white point, to be guided while adjusting (although it’s not a requirement, as even if you only have chosen a white point preset, the white level readout will always be there, too), with one exception: If a display doesn’t allow to reduce the brightness enough using its hardware controls to reach the desired level, then the videoLUTs can be used to achieve that (although using the display controls instead is recommended if possible), and for that, a preset white level is required.

    #7018

    Monstieur
    Participant
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    If I leave “Tone Curve” to “As Measured” to avoid the VCGT altogether, will ICC aware applications still display fully corrected colours (with some bits of resolution lost due to the additional correction required)? The reason being I want to avoid the DispalyCAL Profile Loader / VCGT reset headache altogether when using Windows and 3D LUTs in ReShade / madVR. My PG278Q is so accurate out of the box that it barely shows any difference on the between uncalibrated and calibrated (Colormunki Display) on the macOS desktop. If the difference is so small, is there any point in bothering with 3D LUTs?

    Should I specifically check the “Do not use VCGT” option in addition to “As Measured” for “Tone Curve”?

    • This reply was modified 6 years, 10 months ago by Monstieur.
    • This reply was modified 6 years, 10 months ago by Monstieur.
    • This reply was modified 6 years, 10 months ago by Monstieur.

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    #7022

    Steve Smith
    Participant
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    Hello… My limited understanding  is that the 3D LUT can be made to include it’s own grayscale correcting information. (Or maybe it’s the white point, can’t remember)

    Also I’ve noticed that DisplayCAL’s loader (The one that comes with version 3.2.4) is automatically disabled when Mad VR with a 3D LUT is launched.

    • This reply was modified 6 years, 10 months ago by Steve Smith.
    • This reply was modified 6 years, 10 months ago by Steve Smith.
    #7028

    Florian Höch
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    If I leave “Tone Curve” to “As Measured” to avoid the VCGT altogether, will ICC aware applications still display fully corrected colours (with some bits of resolution lost due to the additional correction required)?

    Yes.

    My PG278Q is so accurate out of the box that it barely shows any difference on the between uncalibrated and calibrated (Colormunki Display) on the macOS desktop. If the difference is so small, is there any point in bothering with 3D LUTs?

    The PG278Q may have accurate grayscale, but its gamut is quite a bit larger than sRGB (not wide-gamut, but somewhat more saturated primaries).

    Should I specifically check the “Do not use VCGT” option in addition to “As Measured” for “Tone Curve”?

    No. madVR can only do the right thing automatically if calibration is included, wheter linear or not.

    #7033

    Monstieur
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    Should I specifically check the “Do not use VCGT” option in addition to “As Measured” for “Tone Curve”?

    No. madVR can only do the right thing automatically if calibration is included, wheter linear or not.

    Why does the madVR preset uncheck “Do not use VCGT” and uses 1553 samples? Is this because the madVR TPG is assumed to be running on a remote machine and not part of the desktop? Both these settings are unnecessary if I create a madVR 3D LUT from the Default preset instead, correct? Is it fine to use a LUT + swapped matrix if the profile is also being used for desktop ICC?

    #7038

    Florian Höch
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    Why does the madVR preset uncheck “Do not use VCGT” and uses 1553 samples?

    The madVR preset is aimed at HTPC use, where desktop grayscale correction is not necessarily desired. More patches are used for higher baseline accuracy.

    Is it fine to use a LUT + swapped matrix if the profile is also being used for desktop ICC?

    If you’re going to be install the profile as display profile, you probably want an accurate matrix (as far as possible), unless you don’t mind limiting yourself to properly color managed application (e.g. the Gimp, Photoshop).

    #7039

    Monstieur
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    The madVR preset is aimed at HTPC use, where desktop grayscale correction is not necessarily desired. More patches are used for higher baseline accuracy.

    So on my desktop PC is it better to just use MPC-HC with ICC and VGCT then? If I were to use 3D LUT, can the VCGT be reset only for madVR in windowed mode?

    #7040

    Florian Höch
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    So on my desktop PC is it better to just use MPC-HC with ICC and VGCT then?

    You can enable calibration if you want it.

    If I were to use 3D LUT, can the VCGT be reset only for madVR in windowed mode?

    Not sure I understand the question. When using a 3D LUT, vcgt is reset during playback, and restored when the player is closed.

    #7041

    Monstieur
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    I mean using MPC-HC’s built in ICC colour management instead of madVR. I don’t care about the other features of madVR – I would only use it for 3D LUT.

    Not sure I understand the question. When using a 3D LUT, vcgt is reset during playback, and restored when the player is closed.

    What does the reset? DisplayCAL Profile Loader using an exception? Or does madVR reset the gamma only within its window because it’s a Direct3D application?

    • This reply was modified 6 years, 10 months ago by Monstieur.
    #7043

    Florian Höch
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    I mean using MPC-HC’s built in ICC colour management instead of madVR. I don’t care about the other features of madVR – I would only use it for 3D LUT.

    If you don’t mind limiting yourself to a 100% output offset gamma curve with exponents 2.2, 2.35 and 2.4 (depending on choice in MPC-HC). I would suggest enabling 10-bit output and floating point processing in MPC-HC.

    What does the reset? DisplayCAL Profile Loader using an exception? Or does madVR reset the gamma only within its window because it’s a Direct3D application?

    madVR resets and restores the calibration by itself. Calibration is not per-window, it is global.

    #7044

    Monstieur
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    If you don’t mind limiting yourself to a 100% output offset gamma curve with exponents 2.2, 2.35 and 2.4 (depending on choice in MPC-HC). I would suggest enabling 10-bit output and floating point processing in MPC-HC.

    What should rendering intent be set to in MPC-HC? How is this related to the same setting in DisplayCAL?

    #7045

    Florian Höch
    Administrator
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    What should rendering intent be set to in MPC-HC?

    Perceptual or relative colorimetric (I think MPC-HC employs BPC, so the two will be quite similar with DisplayCAL generated cLUT profiles).

    How is this related to the same setting in DisplayCAL?

    It select the appropriate table in cLUT-based profiles, if such a table is available. It has no effect for matrix-based profiles.

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