Luminous Landscape Forum
Raw & Post Processing, Printing => Colour Management => Topic started by: huluvu on July 23, 2016, 09:37:07 am
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Hello,
I am successfully hardware-calibrating my NEC screen with a combination of SpectraView Profiler 5 software and an x-rite i1 Display Pro colorimeter. However, I just acquired an i1 Photo Pro 2 spectrophotometer primarily for creating better print profiles (as an upgrade to my ColorMonki Photo).
Now I'm wondering: Should I use the i1 Display Pro colorimeter or the i1 Photo Pro 2 spectrophotometer to calibrate my screen, going forward?
I used to learn that colorimeters are best suited for transmissive media (such as screens) and spectrophotometers are best suited for reflective media (such as paper) – is that still true, regarding these two specific x-rite devices?
Thanks for your input!
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Sounds like you're not in the USA and possibly using the re-badged BasICColor Display5 software that NEC sells as their software in non-USA regions.
Anyway, if you have both units already, I'd probably lean toward using the i1Display Pro for the monitor. People who have used/tested both seem to find it's lower noise in the darkest areas to be slightly 'better'. It'd be an interesting experiment for you to run to use both and switch between them and see.
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Hello,
I am successfully hardware-calibrating my NEC screen with a combination of SpectraView Profiler 5 software and an x-rite i1 Display Pro colorimeter. However, I just acquired an i1 Photo Pro 2 spectrophotometer primarily for creating better print profiles (as an upgrade to my ColorMonki Photo).
Now I'm wondering: Should I use the i1 Display Pro colorimeter or the i1 Photo Pro 2 spectrophotometer to calibrate my screen, going forward?
I used to learn that colorimeters are best suited for transmissive media (such as screens) and spectrophotometers are best suited for reflective media (such as paper) – is that still true, regarding these two specific x-rite devices?
Thanks for your input!
I am not sure it really matters.
Sometimes we have a tendency to insist on 100% accuracy, when we are, in fact, "slicing the baloney to thin" You are never going to see all the colors in you image on the screen, particularly if you are working in ProPhoto.
No matter what you do, you are still, in some areas, working in the dark. Just like sharpening, you have to work with your experience, trust your tools to work with consistency, and, even then, the only measure is the final output.
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I am not sure it really matters.
Sometimes we have a tendency to insist on 100% accuracy, when we are, in fact, "slicing the baloney to thin" You are never going to see all the colors in you image on the screen, particularly if you are working in ProPhoto.
No matter what you do, you are still, in some areas, working in the dark. Just like sharpening, you have to work with your experience, trust your tools to work with consistency, and, even then, the only measure is the final output.
While I would agree that slicing the baloney too thin ends up giving you shred baloney and that the display has limitations in respect of the colours it can reproduce, it still makes sense to begin the process with the instrument that provides the more accurate profiling. Basically, these instruments are reading a succession of patches flashed on the display during the profiling process, so that the software can then compare what is read versus the reference values for those patches and build a profile accordingly. So the question is which instrument will capture and read these patches more accurately. As technology has evolved over the years and there is uncertainty about this, I like Howard's approach: as you have both instruments, do both and see.
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While I would agree that slicing the baloney too thin ends up giving you shred baloney and that the display has limitations in respect of the colours it can reproduce, it still makes sense to begin the process with the instrument that provides the more accurate profiling. Basically, these instruments are reading a succession of patches flashed on the display during the profiling process, so that the software can then compare what is read versus the reference values for those patches and build a profile accordingly. So the question is which instrument will capture and read these patches more accurately. As technology has evolved over the years and there is uncertainty about this, I like Howard's approach: as you have both instruments, do both and see.
There are really only two major producers of 'pucks', x-Rite and DataColor. Are any of these lacking in sufficient accuracy? If you think so, I would appreciate understanding the test data behind it and the significance of it in real life situations. That was the point I was making.
The real importance is that one should calibrate with something.
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There are really only two major producers of 'pucks', x-Rite and DataColor.
There is a third: BasicColor Discus, but it is expensive.
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Sometimes we have a tendency to insist on 100% accuracy, when we are, in fact, "slicing the baloney to thin" You are never going to see all the colors in you image on the screen, particularly if you are working in ProPhoto.
And sometimes, people talk about accuracy without any accuracy metric**, meaning without actual data, it's just another opinion.
The topic/issue has nothing to do with device values that are not colors and hence can't be seen.
As to Colorimeter vs. Spectrophotometer for the display, if you own a good colorimeter, it's going to be a 'better' device for this task, especially in measuring dark colors. If the filter's are not tuned for the display, that's problematic and a Spectrophotometer may do a better job albeit not in shadows. In the old days, we could measure WP with the Spectrophotometer and enter that target, then conduct the rest of the calibration using a Colorimeter. Better units with tuned or updatable filter matrices make this approach unnecessary. So yeah, the i1Display-Pro is the way to fly here. Probably want to skip anything with the name Spyder in it:
http://forum.luminous-landscape.com/index.php?topic=103094.msg845726#msg845726 (http://forum.luminous-landscape.com/index.php?topic=103094.msg845726#msg845726)
The higher the reported dE, the worse the unit preformed. So you'll see two Spyder's (newest models) were 9.9 and 7.2 which is pretty awful. The X-rite products were 1.4 and as low as 0.8!
** Delta-E and color accuracy:
In this 7 minute video I'll cover: What is Delta-E and how we use it to evaluate color differences. Color Accuracy: what it really means, how we measure it using ColorThink Pro and BableColor CT&A. This is an edited subset of a video covering RGB working spaces from raw data (sRGB urban legend Part 1).
Low Rez: https://www.youtube.com/watch?v=Jy0BD5aRV9s&feature=youtu.be (https://www.youtube.com/watch?v=Jy0BD5aRV9s&feature=youtu.be)
High Rez: http://digitaldog.net/files/Delta-E%20and%20Color%20Accuracy%20Video.mp4 (http://digitaldog.net/files/Delta-E%20and%20Color%20Accuracy%20Video.mp4)
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The toolset for using ProPhoto RGB in Photoshop and Lightroom could be greatly improved if they would implement softproofing against the monitor and improve that against printer profiles.
My wish list:
- Selectable DeltaE diffs which would paint the flat overlay. Right now it seems between 5 an 10 for printer profiles and 0 for matrix profiles which will show out of gamut even if the converted color RGB values are color exact but happen to be on the gamut boundary. Ideally, you could select a deltaE. For instance if you were looking at critical colors in a print you might choose 3, less critical 6. And the same should apply to standard matrix profiles.
- When in working space, selecting Ctrl-Alt-Y (instead of shift) to quickly see if any of the colors in the working space are out of the monitor's gamut. When combined with view proof using a printer profile this would quickly let you know if the proof view may be compromised and unable to display printable colors that are in your image. If so you could desaturate in the color settings until the view proof was within the monitor's working range. While the overall color would be desaturated at least you could still see the relative hue and saturation changes without clipping them
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The toolset for using ProPhoto RGB in Photoshop and Lightroom could be greatly improved if they would implement softproofing against the monitor and improve that against printer profiles.
That's kind of been possible in LR for many versions. Compare the display gamut against the working space gamut. We do need it in Photoshop.
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That's kind of been possible in LR for many versions. Compare the display gamut against the working space gamut. We do need it in Photoshop.
I appreciate the info. I've been a Photoshop user forever but only recently had LR available as well. I'll have to take a closer look at it. My understanding is that LR does not provide for Abs. RI. Most of my precision work is repro so Abs. RI is pretty critical which will probably keep me in PS for that portion until they get the option in LR.
Thanks again.
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My understanding is that LR does not provide for Abs. RI.
Not for any color space conversions. You get to pick RelCol or Perceptual.
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As to Colorimeter vs. Spectrophotometer for the display, if you own a good colorimeter, it's going to be a 'better' device for this task, especially in measuring dark colors. If the filter's are not tuned for the display, that's problematic and a Spectrophotometer may do a better job albeit not in shadows. In the old days, we could measure WP with the Spectrophotometer and enter that target, then conduct the rest of the calibration using a Colorimeter. Better units with tuned or updatable filter matrices make this approach unnecessary. So yeah, the i1Display-Pro is the way to fly here. Probably want to skip anything with the name Spyder in it:
Thanks everyone and especially Andrew for your feedback on my initial question.
I don't think I'm sensitive (scientific) enough to make a proper comparison between the i1DisplayPro and the i1Pro2 so I think I'll just keep using the colorimeter for screen profiling and he spectro for print profiling :)
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Thanks everyone and especially Andrew for your feedback on my initial question.
I don't think I'm sensitive (scientific) enough to make a proper comparison between the i1DisplayPro and the i1Pro2 so I think I'll just keep using the colorimeter for screen profiling and he spectro for print profiling :)
Your approach is really quite good. In addition to error from colorimeter filter responses is individual human variations in spectral sensitivity. It's often more variable than even error from low resolution industrial, 10nm, spectros. Andrew's videos describe a way to tweak white points when proofing that is a way to compensate for this. It also is a way to adjust for variations in uV/ OBA effects.
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Your approach is really quite good. In addition to error from colorimeter filter responses is individual human variations in spectral sensitivity. It's often more variable than even error from low resolution industrial, 10nm, spectros. Andrew's videos describe a way to tweak white points when proofing that is a way to compensate for this. It also is a way to adjust for variations in uV/ OBA effects.
...and additivity failures caused by postreceptoral adaptation, and alike :D
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...and additivity failures caused by postreceptoral adaptation, and alike :D
Variation in color perception due to adaptation is far larger in most all circumstances but is not a factor when viewing an illuminated print and a monitor display of a proof with the same XYZ values and the same surround on each. Perceptible differences occur because of spectral differences between the monitor and ink/illuminant print. If a given person's color response matched the CIE matching functions the images would appear identical. They usually don't exactly match because individual human variation of their own color matching functions. This is a particularly big problem in the ultra wide gamut biz where pure (laser) colors are used. Sometimes with 4 or more to get larger gamut coverage. They have found that while they can get super saturated colors visual perception variations are much larger and they produce lower quality color than traditional displays in typical, small gamut use, such as simulating sRGB. It's a somewhat unanticipated problem.
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Variation in color perception due to adaptation is far larger in most all circumstances but is not a factor when viewing an illuminated print and a monitor display of a proof with the same XYZ values and the same surround on each. Perceptible differences occur because of spectral differences between the monitor and ink/illuminant print. If a given person's color response matched the CIE matching functions the images would appear identical. They usually don't exactly match because individual human variation of their own color matching functions. This is a particularly big problem in the ultra wide gamut biz where pure (laser) colors are used. Sometimes with 4 or more to get larger gamut coverage. They have found that while they can get super saturated colors visual perception variations are much larger and they produce lower quality color than traditional displays in typical, small gamut use, such as simulating sRGB. It's a somewhat unanticipated problem.
AFAIK additivity failures were known since introduction of color TV...
Addaptation differences also occur because of spectral differences, as adaptation differs between broadband and narrowband stimuli :)
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There are really only two major producers of 'pucks', x-Rite and DataColor.
There are a lot more than that available, if you are prepared to pay for them:
basICColor DISCUS
Klein K10 etc,
JETI specbos, spectroval etc.
Colorimetry Research CR100, CR-250
Konica Minolta CS-200, CA-210, CA-310 etc,
Photo Research spectrometers & colorimeters.
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AFAIK additivity failures were known since introduction of color TV...
Addaptation differences also occur because of spectral differences, as adaptation differs between broadband and narrowband stimuli :)
Yes, And additivity (putting adaption aside for the moment) failure is going to be most apparent with narrower spectra R, G, and B spectra. Also, additivity failure should be less for smaller gamut (RGB spectra are generally broader) monitors than for the mono freq., experimental wide gamut displays or even just wider gamut monitors. Is the effect enough to credibly argue that sRGB monitors are better suited for color matching (proofing) prints than wider gamut monitors? This could certainly be the case if the printed colors are within sRGB but how far outside that would it have to be for wider gamut monitors to provide a better visual match?
I'm mostly concerned about getting decent proof matches before I commit to print. It might be interesting to view side by side patches proofing on a monitor and a matching Solux illuminated print. Is it possible a sRGB'ish monitor with broader spectral greens could produce better monitor proofs than a wide gamut monitor due to a smaller additive failure?
As an aside, I'm pretty happy with the process I use to set the white point and luminance match (xy tweaked slightly from D50 cords). But, of course, it's based on my sense of color and we do vary.
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Yes, And additivity (putting adaption aside for the moment) failure is going to be most apparent with narrower spectra R, G, and B spectra. Also, additivity failure should be less for smaller gamut (RGB spectra are generally broader) monitors than for the mono freq., experimental wide gamut displays or even just wider gamut monitors. Is the effect enough to credibly argue that sRGB monitors are better suited for color matching (proofing) prints than wider gamut monitors? This could certainly be the case if the printed colors are within sRGB but how far outside that would it have to be for wider gamut monitors to provide a better visual match?
I'm mostly concerned about getting decent proof matches before I commit to print. It might be interesting to view side by side patches proofing on a monitor and a matching Solux illuminated print. Is it possible a sRGB'ish monitor with broader spectral greens could produce better monitor proofs than a wide gamut monitor due to a smaller additive failure?
As an aside, I'm pretty happy with the process I use to set the white point and luminance match (xy tweaked slightly from D50 cords). But, of course, it's based on my sense of color and we do vary.
The softproofed images match good enough so the people usually don't complain. The problem is monitor's white, where the difference is obvious, and where you can see the difference between displays of different backlight spectra calibrated to the same wtpt x,y coordinates. From my personal experience it's not about observer variability - I calibrated monitors with dozens of clients and they saw same issues like me, we usually agreed when it was satisfactorily neutral in most cases, we agreed it was too greenish or pinkish.
Maybe it becomes an issue in case of superwide gamut laser displays, but IMO it also sounds like it might be the problem with adaptation.
From Oicherman: "The existence of adaptation differences between broadband and narrowband stimuli
leading to additivity failures is also long acknowledged (Trezona 1953; Trezona 1954; Stiles
1963; Crawford 1965; Lozano and Palmer 1967; Zaidi 1986). In this study we have established
a relationship between the two, and have shown evidence indicating that both effects are caused
by the same mechanism of postreceptoral adaptation. To our knowledge, this report is the first
to show the consequences of additivity failure in conditions relevant to practical colorimetry.
Since the establishment of colorimetry, the additivity laws were somewhat of a sacred issue.
The general understanding seemed to be that failure of additivity essentially leads to breakdown
of CIE colorimetry and need of redesigning it. Our main conclusion concerning the failure of
additivity is that this is not so: the additivity failure can be predicted, modelled and compensated
for."
"The present research has begun as the research in basic colorimetry. We saw our target in the
development of the new standard deviate observer. The way to approach the goal seemed to be
in collection of large as possible amount of colour matching data. By the end of the first
experiment we knew that we do not need any more data: the set from S&B (Stiles and Burch
1959) study from 50 years ago provides all the information we need. The second experiment
taught us that the new SDO in not needed altogether – at least for the cross-media colour
matching: the observer metamerism does not contribute much to variations in colour matches of
spatially separated stimuli. Moreover: in these conditions, the colour matching itself does not
seem to operate according to classical cone-quantum metamerism model, as the observer’s
adaptation state changes instantaneously when the gaze is moved from one media to another. As
the result, we had to resort to advanced colour difference formulae and chromatic adaptation
transform."
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There are a lot more than that available, if you are prepared to pay for them:
basICColor DISCUS
Klein K10 etc,
JETI specbos, spectroval etc.
Colorimetry Research CR100, CR-250
Konica Minolta CS-200, CA-210, CA-310 etc,
Photo Research spectrometers & colorimeters.
My understanding from an industry source is:
"With the exception of basICColor, which is really only viable in Europe, these are all scientific-grade devices, non-contact meters, not consumer-level tools. Nothing wrong with that, if you have the money, the time, and the pitch-black room to use them in."
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My understanding from an industry source is:
"With the exception of basICColor, which is really only viable in Europe, these are all scientific-grade devices, non-contact meters, not consumer-level tools. Nothing wrong with that, if you have the money, the time, and the pitch-black room to use them in."
Pitch-black room is not necessary, and the Specbos+K10 commonly used by professional calibrators is a very fast combo ;)
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The softproofed images match good enough so the people usually don't complain. The problem is monitor's white, where the difference is obvious, and where you can see the difference between displays of different backlight spectra calibrated to the same wtpt x,y coordinates. From my personal experience it's not about observer variability - I calibrated monitors with dozens of clients and they saw same issues like me, we usually agreed when it was satisfactorily neutral in most cases, we agreed it was too greenish or pinkish.
Maybe it becomes an issue in case of superwide gamut laser displays, but IMO it also sounds like it might be the problem with adaptation.
From Oicherman: "The existence of adaptation differences between broadband and narrowband stimuli
leading to additivity failures is also long acknowledged (Trezona 1953; Trezona 1954; Stiles
1963; Crawford 1965; Lozano and Palmer 1967; Zaidi 1986). In this study we have established
a relationship between the two, and have shown evidence indicating that both effects are caused
by the same mechanism of postreceptoral adaptation. To our knowledge, this report is the first
to show the consequences of additivity failure in conditions relevant to practical colorimetry.
Since the establishment of colorimetry, the additivity laws were somewhat of a sacred issue.
The general understanding seemed to be that failure of additivity essentially leads to breakdown
of CIE colorimetry and need of redesigning it. Our main conclusion concerning the failure of
additivity is that this is not so: the additivity failure can be predicted, modelled and compensated
for."
"The present research has begun as the research in basic colorimetry. We saw our target in the
development of the new standard deviate observer. The way to approach the goal seemed to be
in collection of large as possible amount of colour matching data. By the end of the first
experiment we knew that we do not need any more data: the set from S&B (Stiles and Burch
1959) study from 50 years ago provides all the information we need. The second experiment
taught us that the new SDO in not needed altogether – at least for the cross-media colour
matching: the observer metamerism does not contribute much to variations in colour matches of
spatially separated stimuli. Moreover: in these conditions, the colour matching itself does not
seem to operate according to classical cone-quantum metamerism model, as the observer’s
adaptation state changes instantaneously when the gaze is moved from one media to another. As
the result, we had to resort to advanced colour difference formulae and chromatic adaptation
transform."
I've noticed the same thing and had chalked it up to just personal variation in CMF responses. I've seen a paper where this was investigated and pretty large variations existed amongst so called "normal color perceivers" which group somewhat differently for men and women. Alternately, I assumed it could be poor spike resolution using the I12. My approach has been the same as yours: to tweak the xy target cords so the white points match between my CFL v LED Eizos.
This xy tweak approach would be effective for both additivity failure and individual variation in CMF. That you have seen similar perceivable differences with a large number of different people strongly points to additivity failure. I had only myself as a data point.
This suggests it might be useful to compare a set of graduated printed neutral patches against the monitor showing presumably the same, in standard colorimetric terms, neutral colors. This is a little tricky because one has to illuminate the paper strip on the monitor screen at 45 degrees (to match standard colorimetric measurements) then compensate the monitor patches to add in the reflected color. For white point checking this effect is negligibly small but for darker patches it would have to be accounted for. I'm curious how close (or not) they would be.
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My understanding from an industry source is:
"...these are all scientific-grade devices, non-contact meters, not consumer-level tools.
They are industry tools, and high end TV consumers certainly buy and use them.
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They are industry tools, and high end TV consumers certainly buy and use them.
That's nice. I'll get two for my home setup. 😀😀
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That's nice. I'll get two for my home setup. 😀😀
There's a promo for SpectraVal 1501 and Klein K-80 - AFAIK both are compatible with older brothers ;)
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I've noticed the same thing and had chalked it up to just personal variation in CMF responses. I've seen a paper where this was investigated and pretty large variations existed amongst so called "normal color perceivers" which group somewhat differently for men and women. Alternately, I assumed it could be poor spike resolution using the I12. My approach has been the same as yours: to tweak the xy target cords so the white points match between my CFL v LED Eizos.
This xy tweak approach would be effective for both additivity failure and individual variation in CMF. That you have seen similar perceivable differences with a large number of different people strongly points to additivity failure. I had only myself as a data point.
This suggests it might be useful to compare a set of graduated printed neutral patches against the monitor showing presumably the same, in standard colorimetric terms, neutral colors. This is a little tricky because one has to illuminate the paper strip on the monitor screen at 45 degrees (to match standard colorimetric measurements) then compensate the monitor patches to add in the reflected color. For white point checking this effect is negligibly small but for darker patches it would have to be accounted for. I'm curious how close (or not) they would be.
I just did some ad hoc work testing this approach by creating a series of different brightness neutral patches (the same xy cords). Then printing the same using Rel Col and placing the printed paper on the monitor adjacent to the displayed patches. Paper white using a Solux at 4100 CCT was matched by adjusting the white patch on the monitor. The reflected light from the Solux was only about .2% so it had almost no affect except on very dark patches. There is a significant difference in the colors of the paper white v monitor white using at the same xy cords with an I1 Pro. The "white" visual match occurred with xy cords shifted between .0030 and .0060. There was then quite a good match across the patches. I see no evidence of additivity failure in the neutral patches in the sense that it, if there, is linear and indistinguishable from individual variation of the CMF not to mention the limitations of 10nm resolution. It might be a significant effect with colorful patches but that will require much more work. This would be a nice area for some careful academic work.