Checking monitor calibration

[RedRebel]

There are many discusions about monitor calibration, which colorimeter to use, which software, colour temp setting etc...

But after you have calibrated your monitor using lets say an Optix XR, how do you actualy verify if the monitor colours are right?

...to go one step further (I intend to buy an new monitor) how do you judge the colour capabilities of a monitor? I know that Gretag Macbeth sells colour check cards, but can you use those cards to actualy verify if the monitor is well calibrated and which colour spectrum it can display...or is this a stupid question..

I am not a pro so I just ask...

[Tim Gray]

I don't think there's any way to visually verify the success of the calibration.  Experts could probably detect a problem, but that's an acquired skill.

I also don't think comparing a Gretag card is going to help much either.  The difference in the quality of light between the reflected light of the card and transmitted light of the monitor make such a comparison very difficult for us mere mortals.

Any calibration technique incorporating subjective assessment (eg Adobe Gamma) is fraught with hazzards.

[eronald]

There are a variety of techniques to use. I strongly recommend getting a Gretag Colorchecker chart, it is a reference that once also uses for print comparison. Then you compare the screen image of the chart with your physical chart and this gives you an insight into the quality of calibration and the quality of your monitor.

Also, you need to print some sample imagery *in your favorite syle* on a profiled printer and check against what the monitor is showing - after all this is the purpose of this game.

Another test you should do is create a document in the monitor working space (yes, really), and then create a grey scale gradient in it. This should show you how the shadow and highligts are displaying, and how neutral the profile is. Good screen profiles show both ends, and are smooth, with no bands or reversals.

Edmund

There are many discusions about monitor calibration, which colorimeter to use, which software, colour temp setting etc...

But after you have calibrated your monitor using lets say an Optix XR, how do you actualy verify if the monitor colours are right?

...to go one step further (I intend to buy an new monitor) how do you judge the colour capabilities of a monitor? I know that Gretag Macbeth sells colour check cards, but can you use those cards to actualy verify if the monitor is well calibrated and which colour spectrum it can display...or is this a stupid question..

I am not a pro so I just ask...
[a href=\"index.php?act=findpost&pid=83691\"][{POST_SNAPBACK}][/a]

[61Dynamic]

To save my lazy self some typing, here's Andrew Rodney's article on the subject:
http://www.ppmag.com/reviews/200412_rodneycm.pdf

There are a variety of techniques to use. I strongly recommend getting a Gretag Colorchecker chart, it is a reference that once also uses for print comparison. Then you compare the screen image of the chart with your physical chart and this gives you an insight into the quality of calibration and the quality of your monitor.
Edmund
[a href=\"index.php?act=findpost&pid=83834\"][{POST_SNAPBACK}][/a]

That technique introduces quite a few variables (particularly room lighting) unnecessarily. Testing for blacks and artifacts (refer to linked article) are more effective, not to mention easier since you deal directly with the profile and are not depending upon the subjectivity of your eyes.

[RedRebel]

There are a variety of techniques to use. I strongly recommend getting a Gretag Colorchecker chart, it is a reference that once also uses for print comparison. Then you compare the screen image of the chart with your physical chart and this gives you an insight into the quality of calibration and the quality of your monitor.
[a href=\"index.php?act=findpost&pid=83834\"][{POST_SNAPBACK}][/a]

Okay but if I wan't to compare a colorchecker chart you also need the digital version of the chart to correctly verify what's on your screen versus you chart? Or are these colour numbers available in Photoshop by default?

I did the tests described in the link to Andrew Rodney's article. I had a simillar test from NEC, but that one mainly focusses on the black level and if there are any artifacts showing up in a black-white gradient.


Thanks for posting, it's usfull info

[RedRebel]

PS I just found the GretagMacbeth colour charts in a digital form at: DryCreek

[61Dynamic]

I did the tests described in the link to Andrew Rodney's article. I had a simillar test from NEC, but that one mainly focusses on the black level and if there are any artifacts showing up in a black-white gradient.
Thanks for posting, it's usfull info
[a href=\"index.php?act=findpost&pid=84347\"][{POST_SNAPBACK}][/a]

And that's what counts. If black levels are good and you have a smooth grayscale gradient, all else will render correctly. Looking at all the colors of a color chart will not net you any additional useful information.

[eronald]

And that's what counts. If black levels are good and you have a smooth grayscale gradient, all else will render correctly. Looking at all the colors of a color chart will not net you any additional useful information.
[a href=\"index.php?act=findpost&pid=84401\"][{POST_SNAPBACK}][/a]

Really ? Maybe people who subscribe to this idea just need black and white screens.

Edmund

[indianavince]

Here is my LOW tech calibration method.

I use a one lab to output my critical work on Fuji Crystal Archive paper.

I have a portrait of a couple on my "desktop" that has been printed with no color corections by this lab.  I open the file and reference it to an item I am going to have printed by this lab, and compare it to what is going to go.  I know this sound confusing but it works for me for 4 years now and three computer set-ups.  I find that my Sony Monitor (LCD) and Apple computers don't need much adjustment to make that reference photo "look right" as my benchmark.

I also don't seem to get many complaints if any from images I send for publication to dozens of offset printers each year.  I am always "in the ballpark".

--for what it's worth

[Tim Gray]

There are a variety of techniques to use. I strongly recommend getting a Gretag Colorchecker chart, it is a reference that once also uses for print comparison. Then you compare the screen image of the chart with your physical chart and this gives you an insight into the quality of calibration and the quality of your monitor.

Also, you need to print some sample imagery *in your favorite syle* on a profiled printer and check against what the monitor is showing - after all this is the purpose of this game.

Another test you should do is create a document in the monitor working space (yes, really), and then create a grey scale gradient in it. This should show you how the shadow and highligts are displaying, and how neutral the profile is. Good screen profiles show both ends, and are smooth, with no bands or reversals.

Edmund
[a href=\"index.php?act=findpost&pid=83834\"][{POST_SNAPBACK}][/a]

Just so I understand what you're saying...

I believe the question is predicated on determining the quality of the callibration AFTER you have run an Eye One or Gretag etc etc.  I understand you to be saying that you can eyeball a printed Gretag chart against a displayed chart on a recently callibrated monitor and visually decide that the monitor is not acceptably close enough the the printed chart.  Is that correct?

[pobrien3]

I did the checks after re-profiling today, and the monitor is decidedly NOT right.  I used BasICColor 4.02 on the Eizo CE210W, and the result has a definite magenta cast.  The profile validation shows some pretty ordinary results for the colour patches, and very poor results for the greys (mostly in the red).

Settings - D65, L*, target white 115cd, min black.

What does one do when this happens?  I can drag points on the curves in the adjustment feature the software has, but it's coarse and depends on visual accuracy and a lot of trial and error.

Peter

[pobrien3]

I re-calibrated using 'Native' rather than D65, and the output looks visually more neutral, but still not right.  BasICColor continually fails to hit my brightness target too - I set it for 115, it returned 125 cd.  First time, I set it for 120, it returned 130.

The validation shows that the greys are better (out of the red, at least) but the colour patches fared worse, though they're still in the green zone.

Anyone got any bright ideas?  Is this as good as I can expect from this monitor, or is there something I'm messing up?

[pobrien3]

...I understand you to be saying that you can eyeball a printed Gretag chart against a displayed chart on a recently callibrated monitor and visually decide that the monitor is not acceptably close enough the the printed chart.  Is that correct?[a href=\"index.php?act=findpost&pid=84495\"][{POST_SNAPBACK}][/a]

That is, after all the purpose of the profiling - to match what you see on screen with what comes out of the printer.  I visually check the monitor calibration with a couple of test prints plus a grey ramp / continuous tone, to look for any gross issues.

I'm certainly seeing noticeable colour and neutrality differences between this monitor profile and a well-calibrated print - ones which I didn't have before I changed the monitor.

Peter

[eronald]

I re-calibrated using 'Native' rather than D65, and the output looks visually more neutral, but still not right.  BasICColor continually fails to hit my brightness target too - I set it for 115, it returned 125 cd.  First time, I set it for 120, it returned 130.

The validation shows that the greys are better (out of the red, at least) but the colour patches fared worse, though they're still in the green zone.

Anyone got any bright ideas?  Is this as good as I can expect from this monitor, or is there something I'm messing up?
[a href=\"index.php?act=findpost&pid=84594\"][{POST_SNAPBACK}][/a]

I assume this is an LCD ?

The brightness differential is related to the high native color temperature of the display.
You should let the display warm up for half an hour before calibrating. Backlights fluctuate substantially when warming up.

If you are on a PC, I would recommend checking whether some old pieces of monitor have hooked in profile-loaders, and disable those. Also, I would try firing off a message to Basiccolor, and experiment with some other software eg. ColorEyes.

Maybe your calibration device is unhappy with you or the screen. And then, maybe, if this is a cheap LCD it may be cheap rather than good.

Edmund

[eronald]

Just so I understand what you're saying...

I believe the question is predicated on determining the quality of the callibration AFTER you have run an Eye One or Gretag etc etc.  I understand you to be saying that you can eyeball a printed Gretag chart against a displayed chart on a recently callibrated monitor and visually decide that the monitor is not acceptably close enough the the printed chart.  Is that correct?
[a href=\"index.php?act=findpost&pid=84495\"][{POST_SNAPBACK}][/a]

Correct: You want to check the calibrated monitor against a Colorchecker chart. This chart is not printed, it is actually something more like painted, and unfortunately it's expensive. Putting up an image of this chart on the screen and comparing it to the original is one (just one) of the accepted ways of getting a "feeling" for the quality of the monitor and the calibration software.

Male color consultants, male painters, and much of the female population can actually discern color variations between different production samples of the Colorchecker chart. Consultants may measure the physical  chart and substitute the values into the screen image; however this degree of obsession is probably not healthy

Edmund

[pobrien3]

Edmund, the display is indeed an LCD - it's the Eizo CE210W, definitely not a cheap monitor, marketed as geared towards colour accuracy: one step down from the CG range.  Approximately US$1,200 worth.

Before calibration I ensured the screen and power savers were off, and it warmed up for about four hours whilst I was working at my day job.

This is a new monitor, and a new graphics card (Radeon X1600PRO dual DVI).  I had 2x 20" Apple Cinema Displays before on an Asus card, one of the monitors died.  I de-installed the PowerStrip drivers I created for the ACDs, I did not use WinACD.  I also de-installed all the previous graphics card drivers before loading my new card, and there have never been any other monitors on this system - no possibility for rougue monitor drivers.  I re-added the second, non-dead ACD monitor and it calibrated as well as it did before.

There are no other profile loaders in my PC, I can verify that the correct profile is loaded through the 'Color' WinXP control panel.  I have no other monitor profiles loaded except the ones I create.  Adobe Monitor Gamma (or whatever it's called) has not been on my system ever - that's not interfering.

I demo-tested ColorEyes before I bought BasICColor, I don't think I can demo it again. I'm loath to buy another calibration software unless I can be sure that it will sort out my issue.  One thing in favour of ColorEyes was that I found Jack Bingham to be very helpful and responsive; I doubt I'll get anywhere with BasICColor over the weekend...

[pobrien3]

BTW, the calibration device is the DTP-94

[RedRebel]

BTW, the calibration device is the DTP-94
[a href=\"index.php?act=findpost&pid=84605\"][{POST_SNAPBACK}][/a]

Im am not a calibration expert but the CE210/CE240 are hardware calibrated that means the calibration is done inside the monitor using the Eizo software. If this is true I think their should be no profile active that affects the LUT in the videocard. The video card should have no profile or a neutral one. You could make the mistake that there is a calibration profile active inside the monitor, while another one is active for the videocard. Normaly the video cards LUT is used to calibrate the monitor, but the Eizo CE, CG and some NECS with spectraview software are calibrated inside the monitor. Maybe you should check the Eizo documentation on the subject for calibration and monitor profiling.

I wonder if in your case the black-white gradient looks neutral and without artifacts.

just my $0.02

[Tim Gray]

Correct: You want to check the calibrated monitor against a Colorchecker chart. This chart is not printed, it is actually something more like painted, and unfortunately it's expensive. Putting up an image of this chart on the screen and comparing it to the original is one (just one) of the accepted ways of getting a "feeling" for the quality of the monitor and the calibration software.

Male color consultants, male painters, and much of the female population can actually discern color variations between different production samples of the Colorchecker chart. Consultants may measure the physical  chart and substitute the values into the screen image; however this degree of obsession is probably not healthy

Edmund
[a href=\"index.php?act=findpost&pid=84602\"][{POST_SNAPBACK}][/a]

Ok, you've eyeballed the callibrated monitor next to a gretag chart and decided there are differences that you'd rather not live with.  In my view the skill required to accurately make that judgement is acquired only after __considerable__ experience, and is not likely a skill possess by one just starting out on the color management journey, but regardless....  What next?  

I see only three options (none of which make particular sense to me) 1.  Recallibrate with the same hardware 2. get a different hardware tool, 3. start to manually tweak based on what you see (which makes no sense - why would you bother with hardware callibration if you could get superior callibration manually) - hey - there's always adobe gamma

Having said that, I certainly understand that it's always possible that the hardware callibration device is grossly malfunctioning, and if that's the scenario we're dealing with then I don't have any issues.

FWIW I assume you'll agree that without a controlled light source with which to view the gretag chart you're wasting your time?

[pobrien3]

Im am not a calibration expert but the CE210/CE240 are hardware calibrated that means the calibration is done inside the monitor using the Eizo software. If this is true I think their should be no profile active that affects the LUT in the videocard. The video card should have no profile or a neutral one. You could make the mistake that there is a calibration profile active inside the monitor, while another one is active for the videocard. Normaly the video cards LUT is used to calibrate the monitor, but the Eizo CE, CG and some NECS with spectraview software are calibrated inside the monitor. Maybe you should check the Eizo documentation on the subject for calibration and monitor profiling.

I wonder if in your case the black-white gradient looks neutral and without artifacts.

just my $0.02
[a href=\"index.php?act=findpost&pid=84610\"][{POST_SNAPBACK}][/a]

The gradient looks smooth, but not neutral - there is a pronounced magenta cast.

The BasICColor software takes account of the ability of the monitor to be hardware calibrated, and offers the option for Hardware Calibration (monitor LUTs), which I selected.  I don't know how to check if there is a monitor profile active as well as a video card profile - I don't think so, but I'll do a bit more reading - the Eizo documentation is crap.

Cheers,
Peter