How to get best appearance of projected sRGB images in a dark room?

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  • #7002

    Brett Handley
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    Sorry for the long first post.

    I’m confused over how ambient viewing conditions affect a profile – I’m not sure that a good profile equates to a good perception of an image. I mean if the screen image is very bright in a dark room (lights off), even if the profile is accurate, will the image viewd in a colour managed application be perceived as intended or is shadow detail and contrast affected by the dark lighting conditions?

    Our camera club has recently acquired a bright Epson EB-2250U projector and we view our images for competition in a hall with lights off (because the assumption is that we should have lights off with a projector). The projector is perhaps too bright. I have seen 5000 lumens quoted somewhere for this projector. I have set ECO mode to cut the light output. I set it to SRGB colour mode as we have our members standardise on that for their images. I choose a -2 gamma adjustment in the projector setting as that appears to have more pleasing tonanality. There is a 9 point gamma adjust curve in the projector (adjust by image or adjust by graph) but there’s no help in the manual so I do not yet understand how to set that and whether I should.

    From my understanding the verification report for the profile I created seems pretty good though I worry whether I have set brightness and contrast correctly. Appearance seems bright in the dark room – perhaps more shadow detail is seen than expected, maybe the contrast is affected.
    I worry that cutting the brightness with the brightness control will reduce tonal levels. I would consider experimenting with an ND2 filter or something if that could be made to work to improve image appearance.

    I used a i1 Display 2 propped up, pointed at the screen about 1.5m away to do the profile (at medium quality). I have a color munki too, but it seems to take much longer to profile (at high quality) and I have limited time and access to the hall. I did try to make a colorimeter correction but I got an error that the color munki was in the wrong position when I put it into the projector position, so I gave up on that. I forgot to do an ambient light measurement when I did the profile. I will get a chance to do this again on Monday night.

    I wonder about the gamma for 90 and 95% sample points on the verification report. Does that indicate a problem with my calibration?

    In the mean time, to try to understand the ambient adjustment, I did a calibration/profiling experiment for the display of my surface pro 4, setting ambient to 0.5 lux. I see that the gamma is steeper than previously, but also see that Adobe Bridge colour management lifts the tones to compensate for the steeper gamma – appearing to nullify the ambient measurement effect. Is that right – does it mean that colour managed applications will effectively ignore ambient calibrations – or perhaps I’m really confused?

    I’ve read that one can do a gamut mapping from sRGB for perceptual intent for a dark room destination,  but it seems the only way to use that is in photoshop softproofing. Is this really the right way to get the correct appearance? We typically use Adobe Lightroom or Adobe Bridge to show about 40-50 images to an audience of around 50-100 people so it does not seem feasable to open each one up and soft proof.

    Another concern is that when we have a presenter come with their own laptop and use our projector they may not want to install a profile for it, so getting a good calibration is desirable, but I’m concerned about losing tonal levels due to gross changes in the settings.

    In summary, I would appreciate advice on the steps I should take to calibrate, profile and display sRGB images so they appear as intended using this projector.

    Verification reports attached, before and after profiling.

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    #7030

    Florian Höch
    Administrator
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    If you want to have a viewing conditions adjustment for a dark room in color managed applications, don’t use the calibration ambient light level setting, use the advanced CIECAM02 profiling options (enable perceptual gamut mapping and set target viewing conditions to “projector in dark environment”).

    #7034

    Brett Handley
    Participant
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    Ok thank you.

    So a profile created with this option can be installed as the display profile and does not need soft proofing to get the benefit of the perceptual gamut mapping?

    • This reply was modified 5 years, 4 months ago by Brett Handley.
    #7036

    Florian Höch
    Administrator
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    As long as the program explicitly gives you the choice to use perceptual intent (e.g. the Gimp) you’re set. In Photoshop, you need to use softproofing or convert to profile because the normal view is always relative colorimetric + bpc.

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