Color Calibration hardware - monitor agnostic?

Discussion in 'Mac Accessories' started by macmesser, Jul 1, 2013.

  1. macmesser macrumors 6502a

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    Aug 13, 2012
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    Long Island, NY USA
    #1
    I have a Dell U3014 on order, which I planned to calibrate with my i1 display calibration kit. To my dismay I saw an post elsewhere which claimed that the U3014 is not compatible with the spectraview i1. I had always thought that color calibration solutions were monitor-agnostic. Is this incorrect and if so why?

    Thanks for any insights.
     
  2. mm201 macrumors regular

    Joined:
    Feb 17, 2013
    #2
    In short, the light sensor in your colourimeter may not accurately simulate the human visual system and produce inaccurate results because of the light spectrum of your monitor.

    See here for an explanation of how this is possible.

    If the program is good, it should let you try anyway but the results might be wacky.
     
  3. macmesser, Jul 2, 2013
    Last edited: Jul 2, 2013

    macmesser thread starter macrumors 6502a

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    #3
    Thanks for the link, which is very helpful in sensing the complexity of the topic. I still don't really understand why a calibration system would work with one RGB monitor and not another but I have a better idea of the variables. Will need to research this further, especially with regard to how calibration systems work. Any hardware issue with the calibrator must have to do with the range of its color resolution. Could be the software can't talk with a monitor that has 10^3 bigger vocabulary.

    Assuming two monitors with different dynamic ranges use the same the same red, green and blue (?), they would differ basically in the number of tristimulus values they can display. Also assuming that both monitors would use the same RGB (tristimulus?) value to display any color falling in the smaller color space, metamerism would not be an issue for those colors. One would expect the variation in representation between nearby points in any color space (these would be within the higher dynamic range monitor's space) to be continuous, so even though they could not be precisely represented in the smaller color space they would be more or less calibrated by interpolation. This would mean that even though not really calibrated, the higher range monitor should not display weirdly distorted colors and should in fact "look like" the lower DR monitor, except for finer grained (if not necessarily totally accurate) gradations between similar colors. This is most probably way too simplistic but I'm just trying to get a down and dirty rationale for either keeping the monitor (it came from Amazon yesterday, $989!) or sending it back. If my i1 might calibrate it "good enough for gummint work", or if I can do so in Lion, I'm inclined to keep it and wait for Dell to release Mac software (they should do this soon, right?). I'm a little bummed. Keep thinking I should have picked up an Auria 27" at Microcenter for less than half the price, which would have been perfectly happy with my i1, or an NEC 27". It was the lure of all that real estate that got me.

    Thanks again for any insights.
     
  4. mm201 macrumors regular

    Joined:
    Feb 17, 2013
    #4
    Gamut and bit depth are unrelated. The issue is entirely of spectrum. The colourimeter is built around the assumption that monitors all have a similar backlight spectrum, so the sensors they use are very limited and "fill in the blanks" based on that assumption. (This is an inaccurate explanation but gets the point across. *) Adobe RGB displays have a different spectrum so the sensor's assumptions are wrong for them, leading to inaccurate colour.

    What you have is a very good monitor and I wouldn't suggest taking it back just because it's too good for the spectraview i1 to handle.

    * A more accurate description would be that the colourimeter operates in a different "metamer space" than average human vision and matches your display's colours based on that, producing results which look wrong to you.
     
  5. macmesser thread starter macrumors 6502a

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    Aug 13, 2012
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    Long Island, NY USA
    #5
    Thanks. I understand now why calibration hardware would be not generally be compatible with all RGB monitors. The back-lighting would be taken as neutral by the calibrator, the colors would be sensed by subtracting the backlight contribution. If this backlight contribution is hard wired into the device it won't work with a different backlight. If the calibrator had the ability to actually analyze the spectral power curve of a monitor's backlighting it could then calibrate itself for any particular monitor. I had seen discussions mentioning the distinction between colorimiters and spectrometers but didn't absorb the meaning.

    As for the U3014, I am keeping it. I can either calibrate it by eyeball in Lion or just go with the factory calibration for now. Will know when I try it. Down the pike a bit I'll buy or borrow a spectrometer type calibrator.
     
  6. iLukeJoseph macrumors 6502

    Joined:
    Dec 20, 2011
    #6
    Man did you ever get taken for a loop here. No offense to you MM201, but you took a somewhat simple question and turned it in to a mind numbing (and incorrect) answer.

    First bit depth and gamut are related. At least in regards to a monitor. A monitor with a low bit depth cannot accurately display a large gamut.

    I will start by saying I haven't used spectraview before. But with some quick research Spectraview is software from NEC. The software is not compatible with any other monitors. So maybe that answered your question right there :)

    Now which i1 do you have exactly? There is really no such thing as a "spectraview i1". If it is the older Xrite i1d2 then no that is not compatible with an LED backlight. Now if it is Xrite i1Display Pro then yes you can. You just need different software.

    Actually according to Dell's product page on your monitor. They either have a bit of software or a function built into the monitor to use a i1Display Pro.

    You do NOT need a spectrometer. And believe it or not, a lot of pro TV calibrations prefer using a colorimeter (like the i1 Display Pro). The catch is they will also have a certified spectro to profile the Colorimeter to. Reason some prefer using the colorimeter for the actual calibration process is that it reads faster and almost always performs better in dark grayscale.
     
  7. Bear macrumors G3

    Joined:
    Jul 23, 2002
    Location:
    Sol III - Terra
    #7
    I do know that the original versions of the ColorVision Spyder would not work on LED backlit screens and you needed to buy a new Spyder to be able to calibrate the LED displays. So I suspect there may be something different in the Dell backlight system that is incompatible with how your unit works.

    The question is, did you check with the manufacturer of your calibration unit to ask about compatibility? Also, it's possible that depending on what's different in the Dell, it might only require a software change as opposed to needing an updated piece of hardware.
     
  8. mm201 macrumors regular

    Joined:
    Feb 17, 2013
    #8
    Adobe RGB screens *do* use a different backlight spectrum. (This is necessary to get the wider gamut.) This different spectrum can fool cheap sensors. Websites for these sensors list that they don't support LED or Adobe RGB screens for this exact reason.

    Whether this is the particular problem I can't say since I don't use that calibrator but it's a common enough problem.
     
  9. iLukeJoseph macrumors 6502

    Joined:
    Dec 20, 2011
    #9
    http://www.tftcentral.co.uk/reviews/dell_u3014.htm

    That should answer all your questions.

    And honestly OP if your i1 is a i1D2 depending on the age of it (not how long you owned it, but from when it was actually made). And if you haven't been storing it properly. In a Ziploc Baggie with a moisture absorbing solution, is one example. I can nearly guarantee the sensors have drifted out of spec.

    That's the nice thing about the i1 Display Pro. It is sealed.
     

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