Comparing profiles?

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    Topic: Comparing profiles? Read 24 Times
  • Jeremy Roussak
    Jeremy Roussak
    Gold Member
    Posts: 1014
    Printing Colour Management
    on: May 16, 2024 at 2:09 pm

    This is about projector profiles but there doesn’t seem to be any better forum.

    My camera club has a Canon projector which we use for visiting speakers and also for the monthly club competitions. Someone recently profiled it; I’m not sure what kit he used. He’s sent me the resulting profile, which to my eyes produces results indistinguishable from the Apple-supplied profile for this projector.

    He’s now suggesting that the profile needs to be re-done and wondering if we need to splash out on a better piece of kit to do it. Before we spend any money, I’d like to compare his profile with the Apple-supplied profile using a rather better and more objective tool than my eye.

    Is there some (preferably free) software which will compare two .icm profiles and give some indication, meaningful to an ignoramus (me), how similar / different they are?

    Jeremy

    Mark D Segal
    Mark D Segal
    Silver Member
    Posts: 948
    Re: Comparing profiles?
    Reply #1 on: May 16, 2024 at 2:48 pm

    I don’t know how this would work in the specific case of projectors, but in general the usual way we compare the accuracy of profiles is with bespoke software that runs a set of patches through the profiles and calculates an average and patch-specific dE comparing the references values for the patches with the colour values rendered by the device. Whichever profile shows the lowest dE value would be the more accurate, but to interpret such results you need to know how to relate the dE values to actual perceptions of inaccurate colours.

    Andrew Rodney
    Andrew Rodney
    Participant
    Posts: 403
    Re: Comparing profiles?
    Reply #2 on: May 16, 2024 at 2:57 pm

    What “Apple Projector” profile?

    One can profile a projector using an EyeOne Beamer (a device and an EyeOne Spectrophotometer). It works fairly well only using color-managed applications and only one source, meaning the projector and not the display of the computer. One mirrors the two, only one uses the profile. So if the projected data through the profile looks good, the display looks awful. Noting you can do about that.
    Compare profiles for free, well sure, the Apple ColorSync utility will do this, at least in terms of viewing color gamut. Which doesn’t tell you anything useful about ‘accuracy’ or even the desired color. So I’m not sure what good that would do you. Profile the projector. Pass a known color reference image through it and view the results subjectively. That’s about all you can really do. Again, always use a color-managed application to apply said profile, through data, to the screen (s).

    Author “Color Management for Photographers" & "Photoshop CC Color Management" (pluralsight.com)

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