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Author Topic: Monitor calibration sensor evaluations  (Read 142157 times)

shewhorn

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Re: Monitor calibration sensor evaluations
« Reply #60 on: May 17, 2011, 02:07:15 am »

For a gamma of 2.2 (monitor calibration and working space)

The working space doesn't come into play here, at least when Ethan says he can see the difference between 0 and 1 I'm under the assumption that he's talking about sending 0,0,0 and 1,1,1 straight to a profiled monitor.
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eronald

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Re: Monitor calibration sensor evaluations
« Reply #61 on: May 17, 2011, 07:59:22 am »

What you do to look at the profiled device  is switch into the monitor working space, and then you send the numbers - thus they are profiled device numbers.
For whatever that's worth. The experiment shows just about the best software will be able to do with the profiled device.
I don't know if there is a single reliable experiment you can do to get closer to the hardware.

I think.

Edmund

The working space doesn't come into play here, at least when Ethan says he can see the difference between 0 and 1 I'm under the assumption that he's talking about sending 0,0,0 and 1,1,1 straight to a profiled monitor.
« Last Edit: May 17, 2011, 08:03:55 am by eronald »
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gromit

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Re: Monitor calibration sensor evaluations
« Reply #62 on: May 17, 2011, 06:49:22 pm »

The working space doesn't come into play here, at least when Ethan says he can see the difference between 0 and 1 I'm under the assumption that he's talking about sending 0,0,0 and 1,1,1 straight to a profiled monitor.

A common way of doing so is to set the monitor and working space gamma to the same value ... which is why I mention it. Really you need to read what's said and think about it more rather than just jumping on posts. I still don't understand how this got into a discussion about soft-proofing.
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digitaldog

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Re: Monitor calibration sensor evaluations
« Reply #63 on: May 17, 2011, 10:26:50 pm »

The working space doesn't come into play here, at least when Ethan says he can see the difference between 0 and 1 I'm under the assumption that he's talking about sending 0,0,0 and 1,1,1 straight to a profiled monitor.

Well that’s how the test should be done. You’d build this document and assign the display profile to it, then use the curves test on a rectangle within the middle of the document in full screen mode.

I agree, its useful to be able to have the native calibration of the display show you a visible, albeit subtle difference between 0/0/0 and 1/1/1/.
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gromit

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Re: Monitor calibration sensor evaluations
« Reply #64 on: May 18, 2011, 12:45:10 am »

I agree, its useful to be able to have the native calibration of the display show you a visible, albeit subtle difference between 0/0/0 and 1/1/1/.

As I said elsewhere, most people's monitor calibration gives them an overly optimistic view of shadow detail. It may be handy to see the detail, but it's not accurate and won't be reflected in the print (for a gamma of 2.2).
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digitaldog

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Re: Monitor calibration sensor evaluations
« Reply #65 on: May 18, 2011, 09:09:24 am »

As I said elsewhere, most people's monitor calibration gives them an overly optimistic view of shadow detail. It may be handy to see the detail, but it's not accurate and won't be reflected in the print (for a gamma of 2.2).

But the test isn’t considering prints at all (at this point), only how well the display delivers steps throughout the tonal range. Also not discussed, the test expects the user to view the neutrality (visually of course) of each step in the ramp from black to white as one moves the up arrow on the keyboard using Curves. This test is far from the end all of such tests, but for what it was designed to illustrate, its quite useful.
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gromit

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Re: Monitor calibration sensor evaluations
« Reply #66 on: May 18, 2011, 01:41:37 pm »

But the test isn’t considering prints at all (at this point), only how well the display delivers steps throughout the tonal range. Also not discussed, the test expects the user to view the neutrality (visually of course) of each step in the ramp from black to white as one moves the up arrow on the keyboard using Curves. This test is far from the end all of such tests, but for what it was designed to illustrate, its quite useful.

I understand how the test works and what it shows. The issue is that most don't go the extra step and ask themselves whether, for the gamma chosen, they should see these differences. For a gamma of 2.2, a value of (4,4,4) still only corresponds to an L* of 0.1 which, for all practical purposes, is black.
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digitaldog

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Re: Monitor calibration sensor evaluations
« Reply #67 on: May 18, 2011, 01:43:48 pm »

The test can help decided upon a gamma setting (or we can just select Native and move on).
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Czornyj

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Re: Monitor calibration sensor evaluations
« Reply #68 on: May 19, 2011, 05:06:42 am »

I understand how the test works and what it shows. The issue is that most don't go the extra step and ask themselves whether, for the gamma chosen, they should see these differences. For a gamma of 2.2, a value of (4,4,4) still only corresponds to an L* of 0.1 which, for all practical purposes, is black.

While basically you're right, L* is not the absolute determinant of our perception, as we see lightness in a very relative way. So while it's impossible to see the above mentioned differences in 2° CIE Standard Observer L* viewing conditions, it's not necessarily that hard when we change the surround luminance, use simultaneous contrast effect, and make stimuli larger.

http://www.cis.rit.edu/fairchild/PDFs/AppearanceLec.pdf

shewhorn

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Re: Monitor calibration sensor evaluations
« Reply #69 on: May 19, 2011, 11:18:38 am »

While basically you're right, L* is not the absolute determinant of our perception, as we see lightness in a very relative way. So while it's impossible to see the above mentioned differences in 2° CIE Standard Observer L* viewing conditions, it's not necessarily that hard when we change the surround luminance, use simultaneous contrast effect, and make stimuli larger.

http://www.cis.rit.edu/fairchild/PDFs/AppearanceLec.pdf

That's a very good point to make. If the surround is white (or if the ambient light is too high) I can't tell the difference between 0,0,0 and 1,1,1.

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Alan Goldhammer

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Re: Monitor calibration sensor evaluations
« Reply #70 on: May 19, 2011, 12:16:06 pm »

FWIW, the NEC branded i1 display puck (designed for the NEC wide gamut monitors) works perfectly fine with ArgyllCMS when profiling my NEC P221 monitor.  I was able to use my existing SpectraView built profile as the starting point to create the 500 patch color target for Argyll.  After running the Argyll suite of programs my resulting profile turned out fine with a delta E lower than the ones I usually obtain with SpectraView.  However, as Ethan noted it takes a considerable amount of time to build an Argyll profile and the command line interface is not for everyone.
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shewhorn

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Re: Monitor calibration sensor evaluations
« Reply #71 on: May 19, 2011, 12:57:01 pm »

FWIW, the NEC branded i1 display puck (designed for the NEC wide gamut monitors) works perfectly fine with ArgyllCMS when profiling my NEC P221 monitor. 

I've always wondered if the correction matrix in the puck is available to applications other than Spectraview (in which case it would just work like a regular i1D2) or if it doesn't matter (the correction matrix isn't something that the software accesses and applies, but rather, the matrix is incorporated into the measurements the puck is spitting out to the applications)?

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I was able to use my existing SpectraView built profile as the starting point to create the 500 patch color target for Argyll.  After running the Argyll suite of programs my resulting profile turned out fine with a delta E lower than the ones I usually obtain with SpectraView.

Gotta be a little bit careful about comparing ∆E values reported between packages. Just having a different patch set on which to base your measurements off of can yield dramatically different results, even within the same software package.

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  However, as Ethan noted it takes a considerable amount of time to build an Argyll profile and the command line interface is not for everyone.

Holy crap does it ever!!!  :D  I've been revisiting Argyll over the past 3 days. I'd evaluated it last year for printer profiling but never really explored its monitor profiling capabilities. There are some really neat features in there but WOW... it certainly does take a long time! I really like the ability to make a correction matrix.
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Alan Goldhammer

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Re: Monitor calibration sensor evaluations
« Reply #72 on: May 19, 2011, 01:28:13 pm »

Gotta be a little bit careful about comparing ∆E values reported between packages. Just having a different patch set on which to base your measurements off of can yield dramatically different results, even within the same software package.
Yes, I understand but also need to note that SpectraView only measures the three primaries where Argyll, even in the basic form looks at more patches.  The key thing was that the initial SpectraView white point, black point, and contrast settings were preserved in Argyll which meant I didn't have to fool around with the monitor's hardware adjustment panel.

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Holy crap does it ever!!!  :D  I've been revisiting Argyll over the past 3 days. I'd evaluated it last year for printer profiling but never really explored its monitor profiling capabilities. There are some really neat features in there but WOW... it certainly does take a long time! I really like the ability to make a correction matrix.
Yes, you do have to invest time and effort but given the price of the software it's worth it! :D 
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shewhorn

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Re: Monitor calibration sensor evaluations
« Reply #73 on: May 19, 2011, 05:51:03 pm »

Yes, you do have to invest time and effort but given the price of the software it's worth it! :D 

It certainly is. Having been a software engineer in a former life I'm absolutely floored by the work he's put into this project. A codebase like that is such a HUGE undertaking. I'm really surprised that nobody has put it into a really slick GUI. There's DispCal but... it's pretty rough around the edges. I almost want to dust off OOP books and maybe learn some Objective C and whip together something for the Mac but... time time time. How the heck do you find the time for a regular job AND to code outside of that? Gramme (is that the right spelling) must be super-human.

Cheers, Joe
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Alan Goldhammer

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Re: Monitor calibration sensor evaluations
« Reply #74 on: May 19, 2011, 06:36:34 pm »

It certainly is. Having been a software engineer in a former life I'm absolutely floored by the work he's put into this project. A codebase like that is such a HUGE undertaking. I'm really surprised that nobody has put it into a really slick GUI. There's DispCal but... it's pretty rough around the edges. I almost want to dust off OOP books and maybe learn some Objective C and whip together something for the Mac but... time time time. How the heck do you find the time for a regular job AND to code outside of that? Gramme (is that the right spelling) must be super-human.

Cheers, Joe
I looked at the DispCal GUI but it was more complicated than using the command line and was missing a some features.  I did some Visual C++ programming for fun in the past and writing the GUI is the easiest part of all.  I think the issue with Argyll is that it is constantly evolving (version 1.3.3 was released within the past week or so with more features so anyone supporting a GUI would have to make changes as well.  I'm surprised as you are by the one man show effort that he puts into this and it makes most commercial efforts in color management pale in comparison.  I'm waiting on an i1 unit to arrive and I'm going to do some paper profiling using Argyll.
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Ethan_Hansen

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Re: Monitor calibration sensor evaluations
« Reply #75 on: May 23, 2011, 12:57:22 pm »

We now have a better understanding of how OEM-specific Eye-One Display 2 sensors work. Each i1D2 can be calibrated using a reference spectroradiometer. This both allows tuning the readings to be accurate for a particular display panel's back light characteristics and, perhaps more importantly, significantly reduces the unit-to-unit variability. Our initial sampling of 17 i1D2 sensors showed a mean variation between units when measuring a standard gamut panel set to a 6500K white point at 150 cd/m2 of 7.0 dE-2000. Testing 11 individually calibrated pucks on the same display type as they were calibrated to showed only 3.7 dE average disagreement between sensors. Not spectacular, but a 50% reduction in variability between sensors is not trivial. This put the OEM-tuned i1D2 as less erratic than the Spyder 3, but still more variable than either the i1Pro or DTP-94.

Accuracy of the bespoke i1D2 sensors is still limited to the monitor they are tuned for. It is possible, however, to use a correction matrix for these pucks to improve results on other panel types. This leads one to the conclusion that X-Rite has a marketing opportunity to sell individually calibrated Eye-One sensors tuned to different generic back light types. Targeting standard and wide gamut RGB LED and wide gamut CCFL would be a good start. Also, suppliers of monitor profiling software would be well advised to include correction matrices for different panel back light types.

Thanks to SpectraCAL for pointing me in the right direction and to HP for the generous loan of a box o' pucks.

Mark D Segal

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Re: Monitor calibration sensor evaluations
« Reply #76 on: May 23, 2011, 03:18:39 pm »

Interesting results Ethan. To me it adds up to negative quality progress from XRite between DTP-94 and the various flavours of i1 Display 2. Their first business opportunity should be to make instruments that behave more consistently. And of course if the consistency were also geared to accuracy it would be yet more helpful.
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Czornyj

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Re: Monitor calibration sensor evaluations
« Reply #77 on: May 23, 2011, 04:40:09 pm »

Very interesting - as a logical conclusion it seems that every NEC OEM sensor is individually calibrated...

I'd really like to have some kind of software, that could internally tune an i1d2 to a specific display using some spectroradiometer - I suppose even i1pro or ColorMunki could make things better, and maybe it also could fix the problem with i1d2's tendency to degrade over time.

Speaking of stability - any information regarding basICColor DISCUS testing?

shewhorn

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Re: Monitor calibration sensor evaluations
« Reply #78 on: May 23, 2011, 04:56:33 pm »

I'd really like to have some kind of software, that could internally tune an i1d2 to a specific display using some spectroradiometer - I suppose even i1pro or ColorMunki could make things better

You can do with in Argyll with ccmxmake.

Cheers, Joe
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Czornyj

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Re: Monitor calibration sensor evaluations
« Reply #79 on: May 23, 2011, 06:31:40 pm »

You can do with in Argyll with ccmxmake.

Argyll won't modify colorimeters LUT. At least not yet...
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