Why is displayCAL said to be better?

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  • #3066

    JarrettH
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    Why do a lot of people believe displayCAL calibrates more accurately? How do you know?

    Trust me, I love displayCAL over my Spyder2 software, but are there technical reasons why it should be better? Is the math better? More patches? Something else?

    Spyder2 takes 15-20 minutes, displayCAL takes 90-95 minutes

    Some log examples:

    Spyder2 2.2 @ 6500K

    Black level = 0.4379 cd/m^2
    50% level = 24.90 cd/m^2
    White level = 111.51 cd/m^2
    Aprox. gamma = 2.16
    Contrast ratio = 255:1

    Temperature: 6440-6450K

    Size: 28 kb

    Office & Web (D65, 2.2)

    Black level = 0.4272 cd/m^2
    50% level = 24.33 cd/m^2
    White level = 110.67 cd/m^2
    Aprox. gamma = 2.19
    Contrast ratio = 259:1

    Temperature: ~6515K

    Size: 1,072 kb

    Looks to me like displayCAL is marginally better 🙂 This is on an NEC ea231wmi matte IPS screen.

    • This topic was modified 3 years, 10 months ago by JarrettH.
    • This topic was modified 3 years, 10 months ago by JarrettH.
    #3070

    Florian Höch
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    Hi,

    Why do a lot of people believe displayCAL calibrates more accurately? How do you know?

    If you get a more accurate result than with the vendor software varies on a case by case basis. In some cases, the differences may be small to negligible, in others, noticeably larger. This depends on the hardware (display and measurement instrument), the vendor software itself, and the settings used. The defaults in DisplayCAL are aimed at a compromise of accuracy and speed, with an emphasis more towards accuracy, meaning the profile type will be LUT instead of a more simple matrix profile that some vendor softwares create by default, and the actual display device response is taken into account when laying out the patches that are measured during profiling.

    But you don’t have to wonder, because you can know by running a profile verification (measurement report) with a sufficiently large patch set (the large verification patch set in DisplayCAL for example). This will give you a pretty good idea about the profiling accuracy.

    Some log examples:

    Those are purely informational, they don’t contain enough information that would allow an accuracy or quality assessment.

    #3075

    JarrettH
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    Thanks for your detailed reply, Florian. I’ll check into the measurement reports 

    One quick thing I’m wondering while I wait on this: does a 3d lut cover desktop calibration work too?

    If not, how can you run a 3d lut and the desktop calibration? Don’t the lcd settings always need to change?

    • This reply was modified 3 years, 10 months ago by JarrettH.
    #3078

    Florian Höch
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    does a 3d lut cover desktop calibration work too?

    Not generally, no.

    If not, how can you run a 3d lut and the desktop calibration?

    A 3D LUT can only be applied by software (or hardware) that has 3D LUT support, much in the same way that ICC profiles can only be used by applications that support ICC color management. Only the 1D LUT calibration is always active, because it is loaded into the graphics card gamma table.

    #3079

    JarrettH
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    So I should choose whether I want my desktop calibration active or video? I won’t be toggling my physical LCD settings all the time 😉

    One other thing. The first time I ran the madvr preset my video looked comparatively washed out. I noticed the 2.4 gamma in the profile and thought it was due to that (examples screenshots http://forum.doom9.org/showpost.php?p=1768517&postcount=38145). I ran it again and chose gamma 2.2, and I can tell you even not under controlled conditions that it looks closer to the way it should, in fact maybe even too dark. Would running Rec 1886 at 2.2 improve things?

    #3080

    Florian Höch
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    So I should choose whether I want my desktop calibration active or video?

    If you use madVR, it’ll do that for you, fully automatic.

    One other thing. The first time I ran the madvr preset my video looked comparatively washed out. […] I ran it again and chose gamma 2.2, and I can tell you even not under controlled conditions that it looks closer to the way it should, in fact maybe even too dark.

    Here’s the thing. How do you know which is more correct? The answer is you can’t, unless you know exactly how the material was mastered. As in most situations you don’t have that information, you have to go with a likely default, and for video that is BT. 1886. Ultimately though, this choice is up to you.

    Would running Rec 1886 at 2.2 improve things?

    If you’re looking to increase contrast, then no – that will do the opposite. You probably want to increase the black output offset, while at the same time lowering gamma only slightly.

    #3082

    JarrettH
    Participant
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    Last question I hope…you’ve definitely helped me a lot! Is there a proper way to run the uncalibrated measurement? I see it clears any profile (linear display) but does the LCD need to be factory reset or set to native?

    • This reply was modified 3 years, 10 months ago by JarrettH.
    #3084

    Florian Höch
    Administrator
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    […] does the LCD need to be factory reset or set to native?

    No, although you can do that if you want to get some metrics on the display in factory state.

    #3087

    JarrettH
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    What do you make of this? It’s for the Office & Web preset. Do I need to correct anything?

    https://c2.staticflickr.com/8/7342/26621483594_b550a3a89b_o.png

    • This reply was modified 3 years, 10 months ago by JarrettH.
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    #3097

    Florian Höch
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    Do I need to correct anything?

    You can safely ignore that, it’s a false positive. Generally you don’t ever need the “check measurements” functionality unless you are using the untethered display interface where it can be used to check if the measurements are sane.

    #3109

    JarrettH
    Participant
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    Hey Florian,

    I’ve been observing a lot of drift in my settings, and it’s driving me nuts. My monitor is a CCFL LCD. For example:

    83.9
    75.5
    97.4
    (72 brightness, about 112cdm2) achieves 0.5-0.6 (left of the DE triangle in the interactive window)

    I tried the same settings at night (the room is cooler, zero ambient light this time [but before I pulled the curtain, which made the room dark enough]) and the interactive window displays 1.0-2.0 error (left of the DE triangle) and brightness is down to 110cdm2 (okay, whatever). I fixed the settings using 83.9, 76.6, 98.4 (72 brightness, about 112cdm2) and got it down to 0.2.

    The next morning, after the LCD being on for an hour, the interactive window reported 0.7-0.8 (ambient light present) and 115cdm2. You would think though, that the puck is blocking out all ambient light underneath it.

    I’m not sure what variable is making my settings drift. Am I verifying correctly? Do I need to use the drift compensation? The number to the right of the DE triangle never seemed to change from 00.

    • This reply was modified 3 years, 10 months ago by JarrettH.
    • This reply was modified 3 years, 10 months ago by JarrettH.
    #3122

    Florian Höch
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    You would think though, that the puck is blocking out all ambient light underneath it.

    Only in the area that is covered by the puck – but ambient light can enter over the whole surface of the screen, because the LCD isn’t fully opaque of course.

    I’m not sure what variable is making my settings drift.

    I’m relatively certain it’s the ambient light. Some professional displays come with a hood for that reason.

    Do I need to use the drift compensation?

    That will only help for display/instrument drift, it won’t compensate for different levels of ambient light between calibration runs.

    The number to the right of the DE triangle never seemed to change from 00.

    ΔE*00 is short for delta E 2000, the (currently) most sophisticated delta E formula.

    #3212

    JarrettH
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    p.s. I meant to thank you for this wonderful software. It is clearly better than Spyder’s.

    I opened a grey gradient test in Photoshop CC 2014, assigned the Spyder icm, then assigned the displayCAL icm. With displayCAL the grey ramp was noticeably smoother, and without the blotchy yellow bands present in the Spyder profile.

    It’s also wonderful as a 3D LUT, but takes some getting used to.  I configured mine with gamma 2.2 and black output offset at 80. The depth it adds is so nice, and I’m able to see into low light scenes easier. Fixing the colour casts in shadowy areas helps tremendously to remove the veiled appearance.

    I’m a photographer, so editing in the right environment is part of my workflow: https://www.flickr.com/photos/jehather/

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