hey guys,
i recently started working on my monitor profiles since i bought a new graphics card and i'm about to start editing and colour grading a documentary in november. usually i'm only working (photography) on my calibrated screen, but for editing and grading i added an older (cheap) screen as well as a crt preview monitor to the mix. i wanted to work in rec709 colour space and to have (at least some) colour consistency between these three monitors. i started reading and experimenting and while i made good progress at first, i'm kinda stuck and confused right now.
my problem is that i seem to get weird (very greenish) results when trying to calibrate any of my screens to D65 (or any other white point than its native). it does not matter, whether i use dispcalgui/i1profiler to manually set white point (RGB controls on monitors), or use the native white point of the monitor and let the profile do the rest. i end up with a green result. so green that it hurts my eyes and i'm pretty sure it cannot be a matter of getting used to a new white point.
if any of you has experienced similar problems with adapting, and you think this is a case of user error, please stop reading here and just let me know (but please keep in mind that my case is pretty severe - the weird green appearance persists even after going to work and coming back - and the screens look green in any lighting condition and compared to any other device i have at hand - iphone, macbook pro, macbook air,..). otherwise please continue reading the whole story:
my setup:
main screen: eizo sx2762w (1 year old)
second screen: acer al1906 (very old)
video monitor: sony triniton broadcast monitor (probably even older)
colorimeter: x-rite i1 display 2 (3 years old)
graphics card: geforce gtx760
os: mac osx 10.9 mavericks
software for calibration: dispcalgui+agryllcms and i1profiler lion edition
a little background - here's how colour management started for me: i had bought my i1 display when i was still on my old acer screen. i remember playing around with different settings. iirc i wanted to profile to D65 but couldn't get it to look right (i was put off by the strange green cast i perceived - thought it was the acer's fault..), so i decided to go with native white point and lived happy ever since. last year came my eizo screen and another round of playing with profiling. i again ended up with native white point (because of the green tint). basically all my screens (even laptops) are profiled with native white point. i decided to live with the slight difference in colour as i almost never use them side by side...
a few days ago things changed (the above mentioned three monitor setup) and i decided to do something about colour consistency. i installed dispcalgui and started experimenting. i tried it all: screens calibrated to D65, eizo at native and trying to match acer, the other way round,... i never managed to get an acceptable result. either one, or all of my monitors where greenish. of course i know that i will never reach a perfect match between my eizo and a years old and cheap acer - but i was hoping to be able to get close enough. after some more experiments i decided to live with some inconsistencies but still at least i wanted to have monitors calibrated to D65 (monitor space for photo work and rec709 for video work). and that's where i'm stuck right now. i even cannot get my eizo to look acceptable in D65, neither with dispcalgui nor with i1profiler - that green again. btw, this is your second chance to tell me i would have to wait for my eyes to adapt, but if you still think something else might be wrong continue reading - i tried my best to evaluate the situation and will present some facts now:
my eizo looks about right as is (with standard profile from osx and any profile calibrated at native white point) at any possible white balance setting i can choose (of course it starts looking warm below 5500). 6500 looks very pleasing. as soon as i try to calibrate to D65 or any other setting than native things start to get weird.
finding 1: take a look at the curves that i1profiler shows at the end of the calibration process.
monitor set to 6500 kelvin - calibration set to native
monitor still at 6500 - calibration set to D65:
finding 2:
this one correlates somewhat with finding 1 - and, at least to me, proves that something is wrong...
here's the calibrated reading from within dispcalgui using the profiles from above:
monitor set to 6500 kelvin - calibration set to native:
Current calibration response:
Black level = 0.1795 cd/m^2
50% level = 27.62 cd/m^2
White level = 125.03 cd/m^2
Aprox. gamma = 2.18
Contrast ratio = 697:1
White chromaticity coordinates 0.3714, 0.3326
White Correlated Color Temperature = 3898K, DE 2K to locus = 19.4
White Correlated Daylight Temperature = 4000K, DE 2K to locus = 20.5
White Visual Color Temperature = 4472K, DE 2K to locus = 18.4
White Visual Daylight Temperature = 4471K, DE 2K to locus = 19.9
The instrument can be removed from the screen.
monitor still at 6500 - calibration set to D65:
Current calibration response:
Black level = 0.1795 cd/m^2
50% level = 22.22 cd/m^2
White level = 101.59 cd/m^2
Aprox. gamma = 2.19
Contrast ratio = 566:1
White chromaticity coordinates 0.3130, 0.3293
White Correlated Color Temperature = 6485K, DE 2K to locus = 4.6
White Correlated Daylight Temperature = 6486K, DE 2K to locus = 0.0
White Visual Color Temperature = 6322K, DE 2K to locus = 4.4
White Visual Daylight Temperature = 6486K, DE 2K to locus = 0.0
i'm pretty sure that something's wrong here, and i' guessing that either, my eyes (unlikely), screen (unlikely - i'm having the same problem with the old acer - tests above yield same results, although the courves are not as straight, which was expected) or my colorimeter are completely off target. clearly the i1 display 2 is my prime suspect, but what i find a bit weird is that at my screens' native white points it seems to do a great job...!?
unfortunately i do not have a second colorimeter at hand (yet) to proove or falsify my suspicions. i thought i'd ask here before going out and buying a new one - you know, this wouldn't be the first time that it's actually me who's off target. what do you think?
sorry for the long post!
thanks a bunch,
joerg