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Author Topic: verify calibration  (Read 5180 times)
shacharoren79
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« on: June 25, 2012, 01:41:47 AM »
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hello,

i am using the i1display to try and calibrate my 30" cinema display.

i am using all standard settings:

CCFL monitor
(tried both D65 and Native white points)
native contrast
used the largest patch set provided with the software.

after calibrating it as if it's not perfect.

than i ran a delta E check with the i1profiler and got poor results.

(i'm attaching the results page)

i understood that a reasonable average  delta e should be under 1.5-2

need help

 
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digitaldog
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« Reply #1 on: June 25, 2012, 08:26:22 AM »
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I’d spend less time worrying about that report and check that you have a good screen to print match using the “standard settings” which may very well need to be tweaked.
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Andrew Rodney
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shacharoren79
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« Reply #2 on: June 25, 2012, 08:37:44 AM »
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well im not sure what should i do.

i am sending all my files to print in a lab. asking them not to correct anything.

i can also add, that besides that apple cinema display that i am fighting with, i have here 2 different laptops, another old CRT and a projector

the thing is that in the apple monitor (after calibration) no matter what i do i get like pink/reddish tones that seems wrong.

when i compare the reddish monitor with all other displays there is a noticable difference between the apple (reddish) and all other.

the prints from the lab also don't show the red tint and the pinkish look that i have with the apple monitor.



that's why i was wondering how to check if what i'm seeing is ok, and tried Delta e.

i hope that i explained my situation right.


what should i do next?
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shacharoren79
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« Reply #3 on: June 25, 2012, 08:42:42 AM »
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maybe this will help,

one more odd thing is that every time i'm creating a new profile with the i1profiler i click "create and save ICC profile" at the end of the process.

and 5 minutes after when i'm trying to recalibrate, when it comes to the brightness control adjusments, i need to change it again.

i find that odd since 5 minutes ago i allready did it with the previous profile.

maybe i'm wrong.
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digitaldog
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« Reply #4 on: June 25, 2012, 08:51:55 AM »
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well im not sure what should i do.

i am sending all my files to print in a lab. asking them not to correct anything.

See: http://www.luminous-landscape.com/tutorials/why_are_my_prints_too_dark.shtml

You need to set the calibration targets to produce a visual match to your prints, Lab generated or otherwise.

Forget trying to get a prefect match among differing units. You might get close and, the calibration settings will likely be quite different to get to this result.
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Andrew Rodney
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shacharoren79
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« Reply #5 on: June 25, 2012, 10:16:59 AM »
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ok, so i've read the article twice.

first, just wanted to say that i am not trying to match a few displays, rather i was comparing with my eyes just to better understand and verify that i am seeing the pinkish/reddish cast over my apple monitor.

all the other displays (without any calibration) looks better and closer to prints than my apple after calibration.

things are becoming a bit complicated for me, but i can't give up!

whatever i do, i can't seem to get rid of the reddish cast over my monitor.

i have tried ddifferent options.

is there a documented reason for this reddish cast that i have'nt found yet.

so what exactly does the i1display messure if i input all the different values?
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digitaldog
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« Reply #6 on: June 25, 2012, 11:35:16 AM »
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Red (more specifically a magenta cast) may be due to the white point you’ve set.
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Andrew Rodney
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Ellis Vener
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« Reply #7 on: June 25, 2012, 07:51:48 PM »
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whatever i do, i can't seem to get rid of the reddish cast over my monitor.

i have tried ddifferent options.


Are you sure you are not applying the profile twice?
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Ellis Vener
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shacharoren79
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« Reply #8 on: June 26, 2012, 02:44:14 AM »
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to be honest, i'm not sure of anything at this point.

all i can say is that once i finish measuring the default patch set (the large one - 478) i give the profile a name and hit "create and save profile"

than when i look in the windows color management tab i see that the last name i gave (the profile name) is the default monitor profile.

i don't understand at this point how it is even possible to apply the profile twice.



one more thing that i'd like to add (which is odd) is that the ambient light measurement does not ask for my permission to act and measure from the ambient light from the room.

although at the beginning of the process i DID NOT check the box for "adjust profile based on my ambient light"

so before creating the profile the software have me click the measure button for the ambient light.


but i had the "red/magenta/pink" problem even before the issue with the ambient light.

it is important to say that i have tried to calibrate the monitor 3 times with all settings the same apart from the white point temp.

one time i used 5500k one time 6500 and 7500 just to see what it does.

the reddish cast was with all 3 profiles. 
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digitaldog
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« Reply #9 on: June 26, 2012, 08:48:48 AM »
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Try calibrating using native white point and gamma.
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Andrew Rodney
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« Reply #10 on: June 26, 2012, 10:57:55 PM »
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What video card do you have?
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shacharoren79
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« Reply #11 on: June 27, 2012, 02:46:59 AM »
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well i have an option of native white point,

but the gamma settings (Tone response curve) i have these options:

gamma 1.8

gamma 2.2

gamma 3.0

sRGB


i'm using i1Profiler latest ver.

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shacharoren79
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« Reply #12 on: June 27, 2012, 02:49:34 AM »
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What video card do you have?

i have NVIDIA GeForce GTX 560 Ti with the latest driver.
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digitaldog
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« Reply #13 on: June 27, 2012, 08:45:09 AM »
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well i have an option of native white point,

but the gamma settings (Tone response curve) i have these options:

Try 2.2. The TRC shouldn’t have a big role here in terms of your issue.
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Andrew Rodney
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« Reply #14 on: June 27, 2012, 06:56:29 PM »
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Video cards do matter, mostly because of the LUTs. Google reveals this:

http://forums.nvidia.com/index.php?showtopic=201821&st=540

Perhaps your LUTs are not getting updated or are getting overwritten. If you're not sure, I would make sure you have the latest driver then try whatever people are talking about in that thread.

Note that if you have multiple monitors connected to one card, some cards out there will use the same LUT for both/all monitors resulting in one of them always getting the wrong LUTs.
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shacharoren79
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« Reply #15 on: June 28, 2012, 05:40:07 PM »
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so i dissconected my secondary monitor,

updated the GPU driver to the latest.

and calibrated with gamma 2.2 and native white point.


still same issue.


isn't there a way to verify that the color i'm seeing on the monitor, after creating a profile are correct?

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chrismurphy
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« Reply #16 on: July 20, 2012, 11:05:38 AM »
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What you're describing, one display compared to other displays, with a white point discrepancy even after calibration, sounds to me like a kind of metamerism failure. The calibration matrix of a colorimeter is tied to the spectral power distribution of the display, and this SPD is different display to display. If the instrument calibration matrix isn't well suited for a particular display's spectra, in effect the instrument reports incorrect XYZ values, and you get a color cast.

I suggest you enter a custom white point in xy value for the troubled display, rather than choosing a color temperature value that matches the other displays. You may have to iterate this quite a bit to get a visual match to other displays. Basically you're asking the calibration software to calibrate to a bogus xy value (an error), to compensate for another error. It's imperfect because it will only "fix" white, but should remove the color cast. You still will have some slight discrepancy with colors, most likely.

Another possibility is to borrow a spectroradiometer, calibrate with it to the same color temperature as for the other displays. Then measure the xy value of the calibrated white with your colorimeter and note the xy value. Subsequent calibrations with your instrument, you'd use those xy values.
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