Wrong colors on windows background

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  • #24799

    Yamu
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    When I set an image to become windows background it presents the same colours as on google chrome, having crushed blacks, in general wrong colours. While firefox, photoshop and image viewers with color mangament are all the same showing correct/same colours. How can I make windows background use the right ICC profile sRGB 2.1 instead of the custom profile colour space?

    #24812

    Vincent
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    1 Photoshop/GIMP,  open your JPG/PNG background, asign sRGB profile if it has none

    2 convert to profile <your displayprofile>

    3 save a copy of that file (DO NOT check convert back to sRGB or something like that)

    4 use that 2nd image as background

    • This reply was modified 2 months, 1 week ago by Vincent.
    #25089

    pyron
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    Wouldn’t that force you to “reset video card gamma table”, what’s the point of Profile Loader then if we are doing everything manually?

    • This reply was modified 1 month, 3 weeks ago by pyron.
    #25091

    Vincent
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    Wouldn’t that force you to “reset video card gamma table”, what’s the point of Profile Loader then if we are doing everything manually?

    No. Those profiles are used for images in an image editor. Default display profile in OS is not changed.
    Also 2nd step knows nothing about VCGT, used data from ICC is “after calibration” display description. DisplayCAL LUT3D maker can read VCGT and embed it in its transformations but that is a special feature of that app (to avoid low bitdepth or undithered video LUTs), not a common behavior.

    • This reply was modified 1 month, 3 weeks ago by Vincent. Reason: 2nd step, not 3rd
    #25093

    pyron
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    But still matrix transformation is applied twice? or is the Profile Loader only loading the VCGT?

    I mean Firefox also loads profile data from the same profiles and the usual recommendation is to add an exception to the Profile Loader, now Firefox does read the gamma curves, but also applies matrix transformations.

    #25094

    Vincent
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    But still matrix transformation is applied twice? or is the Profile Loader only loading the VCGT?

    I mean Firefox also loads profile data from the same profiles and the usual recommendation is to add an exception to the Profile Loader, now Firefox does read the gamma curves, but also applies matrix transformations.

    Windows desktop is not color managed. DisplayCAL tray app/profile loader just “publish” display profile to OS  and loads VCGT to GPU. Since desktop is not color managed, color managed apps “ask” OS for display profile.

    So if you choose an image in some colospace and convert it to display colorspace (actually “AFTER grey calibration” colorspace as described in its ICC profile) you get the same colors but encoded in “calibrated” display colorspace. If he saves this new image with its embeded ICC it can be used as he wants in desktop and it will show ok in color managed apps to, but since it is display specific won’t work as intended “desktop image” in other windows computer.
    Also some rounding errors may happen (banding posterization).
    This has nothing to do with VCGT. Maybe you are confusing TRC (tone responde curve, AFTER grey calibration grey response, which color managed apps use) with calibration curves, which is not used unless requested by some apps like LUT3D maker.

    • This reply was modified 1 month, 3 weeks ago by Vincent.
    #25096

    pyron
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    I got VCGT and TRC mixed up. Other than that you are right, I was mistaking Profile Loader should be on 99% of the time.

    • This reply was modified 1 month, 3 weeks ago by pyron.
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