Matching 100% sRGB Laptop + External Display

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  • #19011

    TomS
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    Hi

    Would appreciate your help.

    I have an Asus UX580GD laptop (100% sRGB, IPS display), and a Dell U2417H (99% sRGB, IPS display) as my main screen.  My colorimeter is Spyder 3.
    I’d like to have both displays match as closer as possible, so I can edit photos on each separately and interchangeably.
    The external display’s native white-point is closer to “correct”. The laptop’s has a greenish tendency.

    So far, I’ve only managed to get one of the following results:

    1. Both displays look good (good gradients and general appearance), but they differ in color – the laptop has a slight greenish tint compared to the Dell. This was done using the native white point of the laptop’s display (since it can only be calibrated by SW).
    2. The displays match in color (that’s actually quite impressive – credit to DisplayCal), but the laptop’s display shows posterization in the dark tones. This was achieved by using the driver’s SW to calibrate the laptop’s white point, by reducing the green channel brightness. Bad idea, I know (so the FAQs)… but had to try.

    This lack of success in achieving a good match between the displays seems odd to me. Both claim to be capable of ~100% sRGB… and in practice, people (photographers and others) do work with both laptops and external displays interchangeably.

    Are these the only options? or am I missing something?

    • This topic was modified 4 years, 8 months ago by TomS.
    • This topic was modified 4 years, 8 months ago by TomS.
    • This topic was modified 4 years, 8 months ago by TomS.
    #19019

    Vincent
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    Hi

    Would appreciate your help.

    I have an Asus UX580GD laptop (100% sRGB, IPS display), and a Dell U2417H (99% sRGB, IPS display) as my main screen.  My colorimeter is Spyder 3.

    Not the most suitable measurement device for this task, as you may know.

    The displays match in color (that’s actually quite impressive – credit to DisplayCal), but the laptop’s display shows posterization in the dark tones. This was achieved by using the driver’s SW to calibrate the laptop’s white point, by reducing the green channel brightness. Bad idea, I know (so the FAQs)… but had to try.

    Instead of relying in GPU driver options use DisplayCAL visual point editor.
    This correction is goin to be translated to GPU LUT calibration in displaycal reducing one or two channel maximum output.
    Some driver options are know to use low precision for this task while 16bit calibration computation from DisplayCAL may help you there.
    But… most laptop GPU are known to have limited precision LUTs (iGPU) so you may get banding after calibration too even if the calibration calculated by DisplayCAL is smooth without those steps you see.
    Anyway, it would be worth trying: DisplayCAL visual white point editor. should be in the doc or faqs.

    This lack of success in achieving a good match between the displays seems odd to me. Both claim to be capable of ~100% sRGB… and in practice, people (photographers and others) do work with both laptops and external displays interchangeably.

    Are these the only options? or am I missing something?

    There are more options but they are not cheap.
    -Best one is to get an spectrophotometer and a good colorimeter. Measure displays’ RGBW with spectro, then compute a correction for a colorimeter. Measure & calibrate with colorimeter.
    -Get a better colorimimeter (i1d3 family) and use their sets of bundled corrections (instead a custom one made with an spectrophotometer for your displays) + perhaps a little visual whitepoint editor to match white.
    -Use an external display with reliable (and that means not cheap: Eizo Cs or NEC PAs or better) HW calibration, so you not depend on laptop’s GPU (lack of) precision/dithering. In the same way some laptop manufactures are including what looks like a basic HW calibration suite but I suspect that they took the same basic approach full of simplifications like lesser monitor’s HW calibration suites (Dells, Benq and such) so you may (or not) end needing a little correction in GPU done with DisplayCAL… which again makes you GPU precision dependent (this lack of precision may be visible… or not).

    • This reply was modified 4 years, 8 months ago by Vincent.

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    #19021

    Vincent
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    This lack of success in achieving a good match between the displays seems odd to me. Both claim to be capable of ~100% sRGB… and in practice, people (photographers and others) do work with both laptops and external displays interchangeably.

    Also this is a misconception.

    Coverage % value of some colorspace it’s just an intersection ratio of two sets… or volume solids in a 3D space.
    You can have a cube of 5cm side and call it sRGB.  Then you can have two big boxes (2 displays) of different sizes (different native gamuts) that can hold that cube inside. Coverage will be 100% for them… but they are not equal.
    This is an extreme example, usually these 100% sRGB (without any other % coverage advertisement) are very close to the shape of sRGB colorspace if you represent their gamut in a 3D space. The portion of gamut outside sRGB is small but if you do not use those screens under color managed applications there could be a noticeable difference between sRGB 255 red, display 1 native gamut 255 red and display2 natiev 255 red: for example Windows desktop and microsoft browsers or default Windows 10 Photo app.

    Even with 2 units of the same model of screen you can get a visual mismatch in white. Each display can have the same spectral power distribution signature in their RGB primaries (same technology, same model)… but the “gain” of each one may be sligthly different for each display. This is what you tweak in display OSD controls “RGB gain” options, or what you did in GPU driver.
    In this favorable situation (same model, 2 units) it will be easy to find an equivalent gain for each display output but if you need to rely on limited 8bit precision (like some GPU laptops driver, what you did) rounding errors may arise, and you see banding/posterization.

    #19026

    TomS
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    Thank you for  your detailed reply Vincent.

    I understand what you meant regarding the sRGB coverage. Probably explains the issue.

    Regarding the Spyder 3 – starting to think about replacing it  but it might take some time as the alternative is quite expensive.

    Let me just check if I understand what you wrote about the visual whitepoint tool. So I should calibrate my main (external) screen – with the RGB calibrated according to the measurements at the beginning of the calibration process. Then, visually choose a whitepoint on the laptop that looks  like the main screen’s white. Then start the calibration (on the laptop), and ignore the interactive measurements when calibration starts (i.e. if they show it’s too green – leave it like that and start anyway)?

    Thanks again

    Tom

    #19027

    TomS
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    Just to correct my previous reply – meant use the whitepoint tool to measure the whitepoint on the main screen, then calibrate the laptop with it (and ignore the interactive color measurements at the start of the calibration process).
    Is that what you meant?
    Thanks

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