How do whitepoint chromaticity coordinates work?

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  • #23727

    second
    Participant
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    Hello,

    I’m trying to calibrate my display with the Spyder 5. My goal is to achieve a perfect calibration for photo editing. So I chose “sRGB” under “Settings”. In the calibration tab is “Whitepoint” now set to “Chromaticity coordinates” which have already some x and y values. Why is that? Shouldn’t it be 0? Also when I go into the “Visual whitepoint editor” there is always a value of 252 Red, 255 Green, 252 Blue. If I change them to white (255/255/255) it switches back if I open the editor again.

    I’m just trying to understand how those “whitepoint chromaticity coordinates” work. Or can I just switch the whitepoint to “Color temperature” and set it to 6500K, which is the value I want the display to have?

    Sorry I’m absolutely new to Display Cal.

    #23771

    Florian Höch
    Administrator
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    In the calibration tab is “Whitepoint” now set to “Chromaticity coordinates” which have already some x and y values. Why is that? Shouldn’t it be 0?

    Chromaticity coordinates allow more fine-grained control over the whitepoint than, say, a correlated color temperature (CCT). They can never be zero.

    Also when I go into the “Visual whitepoint editor” there is always a value of 252 Red, 255 Green, 252 Blue. If I change them to white (255/255/255) it switches back if I open the editor again.

    Yes. It will use the current calibration as a starting point. You will not need to use the visual whitepoint editor unless you want to closely match several displays.

    #23842

    second
    Participant
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    Thanks for your answer. I left it at the default settings (sRGB). The calibration result looks good but compared to a white sheet of paper too reddish. It also seems to have no effect on colors but only on contrast.

    Is “Color temperature” set to 6500K maybe better or should I choose “Gamma 2.2” instead of “sRGB” in the settings?

    #24109

    Florian Höch
    Administrator
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    I do not know which whitepoint you calibrated to, but if it’s far from the generic D65 equivalent (6500K or xy 0.3127 0.329) or the colorimeter correction you used is not suitable for your display/backlight type, then this influences the result. Note that most paper has optical brighteners added in which make the paper appear “whiter” (more blue) than it would be without, and it also depends under which lighting you are viewing the paper.

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