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Author Topic: Calibrating an HP ZR24w monitor with an i1D2?  (Read 7984 times)
ChasP505
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« Reply #20 on: July 08, 2010, 10:39:06 AM »
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Quote from: Jessica Holden
So where it stands right now, I have my monitor back on the default profile (in my Color Management window, for the monitor, I have it set back to the "default HP ZR24w LCD Monitor" profile, called HP_zr24w.icm), but the OSD is at the settings I set last time I calibrated (I used Target 6500, Brightness 110, and Gamma 2.2, and ended up with brightness 29, contrast 99, and RGB at 72/30/47). But that was still too red, though, so I gave in and just manually eyeballed the RGB channels in the OSD with my photos open in CS5, and when I move the red slider down to 56, green at 30, and blue to 52, and it's pretty darned spot on to those photos. So that's where my OSD settings are now.

Jessica, besides all the other discussion going on...  I'm appalled that you had to move the RGB controls so far from their default 255-255-255 settings.  Have you tried leaving them at their native default settings and allowing the software to do the work of adjusting the white balance?
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Chas P.
shewhorn
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« Reply #21 on: July 08, 2010, 05:27:49 PM »
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Quote from: ChasP505
Jessica, besides all the other discussion going on...  I'm appalled that you had to move the RGB controls so far from their default 255-255-255 settings.

ETA - see post 25 for an update to my thoughts with regards to the rgb values, I'm not entirely on the ball tonight

Why? 255, 255, 255 represents the "native" white point. The native white point of the screen and the white point of your print more often than not have absolutely nothing to do with one another. In addition, the numbers that colorimters return may as well be arbitrary values. They are not lab grade devices and the variability from instrument to instrument can easily be 1800K. This presents a problem because when you enter a value for the color temperature you're going to have issues if you expect your screen to actually be that color temp (even though the puck says it is) when all is done. Colorimeters are good for relative profiling... if the colors are out of whack, it brings them back in. If you want an accurate screen to print match and you're using a proper full spectrum bulb and an ICC profile from your lab for soft proofing, then you're going to need to adjust the color temp of your screen to match up with the light source/paper white combo. The color temp of the light source you use will have an impact on what color temp your screen should be at.

Cheers, Joe
« Last Edit: July 08, 2010, 09:07:18 PM by shewhorn » Logged
WombatHorror
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« Reply #22 on: July 08, 2010, 06:13:14 PM »
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Quote from: shewhorn
Why? 255, 255, 255 represents the "native" white point. The native white point of the screen and the white point of your print more often than not have absolutely nothing to do with one another. In addition, the numbers that colorimters return may as well be arbitrary values. They are not lab grade devices and the variability from instrument to instrument can easily be 1800K. This presents a problem because when you enter a value for the color temperature you're going to have issues if you expect your screen to actually be that color temp (even though the puck says it is) when all is done. Colorimeters are good for relative profiling... if the colors are out of whack, it brings them back in. If you want an accurate screen to print match and you're using a proper full spectrum bulb and an ICC profile from your lab for soft proofing, then you're going to need to adjust the color temp of your screen to match up with the light source/paper white combo. The color temp of the light source you use will have an impact on what color temp your screen should be at.

Cheers, Joe

a good colorimeter should be able to do an order of magnitude better than 1800K off
so i would definitely worry about being 2000K off
but it is true that you really can't get thing down to the .001 either
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shewhorn
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« Reply #23 on: July 08, 2010, 08:56:36 PM »
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Quote from: LarryBaum
a good colorimeter should be able to do an order of magnitude better than 1800K off
so i would definitely worry about being 2000K off
but it is true that you really can't get thing down to the .001 either

I should probably quantify that a little more but let me assure you that these are real values from real colorimeters and they can be that far off from one another.

Spyder 3s from what I've observed tend to report a measured value as being cooler than it actually is. DTP94s by comparison report a measured value as being warmer than it actually is. Eye Ones are somewhere in the middle. If profile my monitor to say D65 with my i1 Pro and the measure the same white point with the Spyder 3 and the DTP94 I will get values of 7400K and 5600K respectively. The delta is +/- 900K in what these pucks are reporting back. They are not to be relied upon for accurate profiling of white point.

ETA - Now these are the differences I've noticed from one manufacturer to another. If you compare the same device to the same device you won't see quite that delta but I have seen 400K differences between two devices of the same make and model.

Cheers, Joe
« Last Edit: July 08, 2010, 09:00:47 PM by shewhorn » Logged
shewhorn
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« Reply #24 on: July 08, 2010, 09:05:50 PM »
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Quote from: ChasP505
Jessica, besides all the other discussion going on...  I'm appalled that you had to move the RGB controls so far from their default 255-255-255 settings.  Have you tried leaving them at their native default settings and allowing the software to do the work of adjusting the white balance?

Okay...

I gotta say though... yeah, those numbers do seem way off. Sorry... I'm a bit frazzled today. I have about 5 things exploding in my face at the moment so I'm lacking a bit of clarity. I suspect the luminance on the screen is too bright for the target value. Ideally one of those channels should be at 255 and one or two of them should be tweaked to get to the desired color temp. My apologies, you are correct. Something is off.

Cheers, Joe
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WombatHorror
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« Reply #25 on: July 08, 2010, 10:13:18 PM »
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Quote from: shewhorn
I should probably quantify that a little more but let me assure you that these are real values from real colorimeters and they can be that far off from one another.

Spyder 3s from what I've observed tend to report a measured value as being cooler than it actually is. DTP94s by comparison report a measured value as being warmer than it actually is. Eye Ones are somewhere in the middle. If profile my monitor to say D65 with my i1 Pro and the measure the same white point with the Spyder 3 and the DTP94 I will get values of 7400K and 5600K respectively. The delta is +/- 900K in what these pucks are reporting back. They are not to be relied upon for accurate profiling of white point.

ETA - Now these are the differences I've noticed from one manufacturer to another. If you compare the same device to the same device you won't see quite that delta but I have seen 400K differences between two devices of the same make and model.

Cheers, Joe

Well I have heard that as many as a third of a spyder 3s can be like 15dE or more off.

I'm surprised the DTP94b and Eye1Pro were so far apart. I haven't heard of a huge 900K difference reported elsewhere.
Both DTP actually make my HDTV look a bit redder then when using an I1D2 which would mean they are reading cooler than the I1D2.

The two DTP94 that I tried only reported about 60-80K difference in color temp on an sRGB monitor (for some reason they were more like 200-300k off using icolor generic matrix on a wide gamut though).

I used to have a spyder2 that tended to make everything look red.

Did you try them on perhaps LED backlit panels?
(or wide gamut?)


anyway, interesting, i will have to look into it more
my NEC PA (suing NEC puck calibrated sRGB mode or factory sRGB mode) with either metamerism on or off doesn't really look the same in the grays as my DTP94 calibrated samsung monitor
« Last Edit: July 09, 2010, 05:22:14 PM by LarryBaum » Logged
David Saffir
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« Reply #26 on: July 08, 2010, 11:15:12 PM »
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I agree with Ernst. Try a Color Munki or other spectro.

David
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shewhorn
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« Reply #27 on: July 09, 2010, 09:54:28 AM »
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Quote from: LarryBaum
Did you try them on perhaps LED backlit panels?
(or wide gamut?)

anyway, interesting

I've tried them on displays with white LED backlights, CCFL backlights, screens that are wide gamut, and screens that pretty much stick to the gamut of sRGB (and always after letting the monitors and the pucks warm up to a stable operating temp). Not only did the color temps vary but the reported luminance varied by as much as 15 cd/m^2 between instruments as well.

What I got out of it was, you can't rely upon a colorimeter to hit a quantifiable value. They're kind of like body fat monitors that are based on resistance. They aren't at all accurate at calculating body fat but used consistently, they do allow you to track relative changes. They do however allow you establish a reproducible standard relative to themselves and that is good enough for maintaining quality control. What you can't do is establish consistent control at remote sites with different pucks so... if you and I both had an NEC 2690 and we both calibrated/profiled to D65, gamma 2.2, @ 110 cd/m^2, we would end up with different results, especially if we had pucks from different manufacturers. Complicating matters more though is the fact that even different software will report back a different value for the SAME white point so there's lots of variables here.

If you want more consistency from instrument to instrument, and something that will get you closer to actual quantifiable values, in theory you would have to move to a spectrophotometer. I haven't as of yet had the opportunity to compare spectros to one another. I do have a Spectroscan/Spectrolino and an i1 Pro... one of these days I'll compare them to see how close they are. In an ideal world they'd render the same values but I know they do not do that as the Spectrolino is dramaticlly better in the shadows.

Cheers, Joe
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WombatHorror
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« Reply #28 on: July 10, 2010, 05:57:10 PM »
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Quote from: shewhorn
I should probably quantify that a little more but let me assure you that these are real values from real colorimeters and they can be that far off from one another.

Spyder 3s from what I've observed tend to report a measured value as being cooler than it actually is. DTP94s by comparison report a measured value as being warmer than it actually is. Eye Ones are somewhere in the middle. If profile my monitor to say D65 with my i1 Pro and the measure the same white point with the Spyder 3 and the DTP94 I will get values of 7400K and 5600K respectively. The delta is +/- 900K in what these pucks are reporting back. They are not to be relied upon for accurate profiling of white point.

ETA - Now these are the differences I've noticed from one manufacturer to another. If you compare the same device to the same device you won't see quite that delta but I have seen 400K differences between two devices of the same make and model.

Cheers, Joe

I'm starting to think you may be right (sort of, I do seem to be noticing differences only I'm getting the DTP94b reading things as cooler than they actually may be and the other probes warmer, the exact opposite of what you wrote; EDIT: actually maybe not, it seems that it is perhaps making profiles end up with too much blue and not enough green, anyway whatever the exact details I think you are likely right about DTP94 perhaps not getting white point exactly on spec), at least about the differences in color temp various probes may read.

I just compared a DTP94b calibrated (but not profiled) sRGB CCFL LCD HDTV to a color checker chart (viewed during the day with windows open, but the sun not directly on it, so hopefully that is vaguely D65) and did the same for the set calibrated by the NEC custom puck and the same for NEC PA calibrated with NEC puck and using factory defaults.

The NEC (i1D2) calibrated HDTV looked way red, nothing more needs to be said.

The DTP94b calibrated Samsung CCFL LCD sRGB HDTV and Samsung sRGB monitor actually didn't seem to match quite as closely as the either the NEC PA with SVII+NEC puck or simply using the factory preset.

to be honest none of the displays really matched the checked when it was held up with each color side by side, even the NEC seemed noticeably off, but it did seem to be the closest overall and if the chart was held closeish but not too close it at least looked somewhat ballpark, the other displays needed the color checker held much farther away for things to begin to look ballpark.

Of course I really need to use a D65 lamp to be sure. (then again it seems that ones with a good spectral response cost rather a lot)

(of course you also mention that different software provides different values too and that was certainly an element in play here, very different software and calibration methods)
« Last Edit: July 11, 2010, 01:27:43 PM by LarryBaum » Logged
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