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Author Topic: Barbieri M3 Polarized profiles - worth it for PK papers?  (Read 1327 times)

narikin

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Barbieri M3 Polarized profiles - worth it for PK papers?
« on: December 15, 2018, 09:21:49 pm »

Thanks to Mark for the interesting review of RR Smooth Rag and outlining the use of M3 polarized profiles for improved shadow differentiation.

Might I ask, as a relative amateur in this (with just isIs and i1Profiler) if the improved shadow definition is just applicable to MK papers, as reviewed, or would be across the board - for example on quality PKs like Hahn Photo Rag or Canson Platine/Baryta?

I get that the shadow definition comes at the cost of less accurate profiling otherwise, but on occasions, this might be a trade worth making.

Thanks
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Mark D Segal

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #1 on: December 15, 2018, 11:13:53 pm »

It's much less important for deep quartertone appearance with the better PK papers because Maxmimum Black is much deeper and the tonal range considerably wider, permitting more tonal differentiation with those papers.
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Doug Gray

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #2 on: December 16, 2018, 12:37:42 am »

It's much less important for deep quartertone appearance with the better PK papers because Maxmimum Black is much deeper and the tonal range considerably wider, permitting more tonal differentiation with those papers.

I concur.

Also, if anyone has both M3 and M2 profiles made with the same printer and MK and PK I'd be interested in looking at the effects of M3 v M2 by comparing profiles in Matlab. MK papers should see significant gamut expansion including lower BP. PK papers much less so.

I should mention, since it may not be obvious to all readers, that if the M3 MK gamuts are materially larger than the M2 gamuts, colors printed with the M3 profile will have somewhat desaturated colors compared to those printed with the M2 profile. However, it probably will be close enough not to be observable unless two identical prints using M2/M3 are viewed side by side.

The advantage of M3 profiles is, as Mark noted, much smoother tonal change in shadows. It accomplishes something similar to a good quality BPC by spreading it out over more LUTs and with better resolution from the spectro.
« Last Edit: December 16, 2018, 12:46:26 am by Doug Gray »
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aaronchan

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #3 on: December 16, 2018, 11:39:49 am »

I concur.

Also, if anyone has both M3 and M2 profiles made with the same printer and MK and PK I'd be interested in looking at the effects of M3 v M2 by comparing profiles in Matlab. MK papers should see significant gamut expansion including lower BP. PK papers much less so.

I should mention, since it may not be obvious to all readers, that if the M3 MK gamuts are materially larger than the M2 gamuts, colors printed with the M3 profile will have somewhat desaturated colors compared to those printed with the M2 profile. However, it probably will be close enough not to be observable unless two identical prints using M2/M3 are viewed side by side.

The advantage of M3 profiles is, as Mark noted, much smoother tonal change in shadows. It accomplishes something similar to a good quality BPC by spreading it out over more LUTs and with better resolution from the spectro.

I agree with you as well.
But there is another special paper that I would like to compare m2 vs m3 as well which is Metallic Paper.

Aaron

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #4 on: December 17, 2018, 12:38:37 pm »

But there is another special paper that I would like to compare m2 vs m3 as well which is Metallic Paper.

In most but not all cases we found that polarized measurements produce the best results with metallic papers when measured with standard 45/0 spectrophotometers. These instruments are specular excluded; the specular (gloss) reflection component is not captured. Usually this produces the best visual match as human vision combines gloss and texture into perceived color. Measurements of two surfaces with the same actual color, one matte, the other highly glossy, will give different values with a 45/0 spectrophotometer. A spherical spectro will show the colors as being identical. Look at the surface straight on under diffuse light and your eyes will see the same color. Any angular shift or lighting angle, however, and your eyes will perceive color differences more in line with the 45/0 measurements.

Polarized instruments eliminate much of the effect of surface reflections, making a 45/0 instrument behave closer to a spherical spectro. Traditionally polarized filters are used when comparing wet to dry ink samples. As ink dries, surface reflections decrease apparent density values. Polarized filters improve matching between wet and dry samples.

Pearlescent surfaces, however, react visually differently. How surface specularity affects colors depends on the color itself and interactions with the paper substrate. Many metallic papers behave visually as though surface reflection as either absent or minimized. Dark colors in particular are seen as having higher density than what a 45/0 instrument gives. Slapping a polarizer in front of the measurement aperture results in measuring light that is diffusely reflected from within the color layer rather than the surface.

In some cases, we have combined polarized and non-polarized measurements when building profiles. Some years ago we created profiles for a museum that was selling reproductions of their collection printed on metallic papers. I spent all too many hours beating my head against measurements from spherical and 45/0 instruments in combination with 60 degree measurements that gave the true gloss component. Combining M3 (polarized) with M2 data did the trick. The results were not mathematically as good as other options but visually - no question as to which one looked better.

Josh-H

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #5 on: December 26, 2018, 01:35:58 am »

I have also done some very extensive testing of M2 vs. M3 with matt papers. I have been using the Barbieri for M3 and the Xrite ISISXL2 for M2. Well, I actually use the ISIS2XL to make M0, M1 and M2 scans.

A few observations.

1. The angle and position of the polariser in the Barbieri is hyper critical to the results. shifting it even a fraction of a mm makes a very noticeable difference in the results. Given how critical it is there really should me a micrometer for moving the polariser and there isn't. It has to be done by trial and error and is extremely time consuming to get right.

2. There is no question that M3 reads deeper into the shadows than M2 with matt papers. With gloss papers the advantage of M3 disappears. The difference is very significant on matt paper with M3 vs. M2. However, if you turn on Black Point Compensation when you make a print with an M2 profile on matt paper the shadow detail results are identical to M3 printed without BPC turned on.

3. I have found M3 to be less accurate in some colors than M2. For example, I get a more accurate match in the oranges with the M2 profile vs. M3. I cannot pin down why this is the case, except to say that the polarisation is having some sort of effect.

4. All of the above are repeatable in multiple tests with the same results.

A few other notes: I have found the Xrite ISISXL2 produces better profiles when you select 'Colourful' and not the default. The gamut improves. And always select 'Best / Highest Quality.

My final conclusions on M2 vs. M3 are that if you print with an M2 profile you must use BPC to get good shadow detail. With M3 you dont need to turn on BPC. However, I find the M2 profile more accurate in certain colors than the M3.

I cant comment on metallic papers as I have not done any testing with those. I am primarily a matter paper printer.
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Mark D Segal

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #6 on: December 26, 2018, 08:23:22 am »

Hi Josh,

Your comments 2,3,4 cohere pretty much with my findings.

Mark
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Mark D Segal (formerly MarkDS)
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Doug Gray

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #7 on: December 26, 2018, 03:20:33 pm »

I have also done some very extensive testing of M2 vs. M3 with matt papers. I have been using the Barbieri for M3 and the Xrite ISISXL2 for M2. Well, I actually use the ISIS2XL to make M0, M1 and M2 scans.

A few observations.

2. There is no question that M3 reads deeper into the shadows than M2 with matt papers. With gloss papers the advantage of M3 disappears. The difference is very significant on matt paper with M3 vs. M2. However, if you turn on Black Point Compensation when you make a print with an M2 profile on matt paper the shadow detail results are identical to M3 printed without BPC turned on.

This is predicted from the physics of reflected light. M3 strongly attenuates light reflected from the resin surface of pigment inks. The 45/0 geometry of spectrophotometers, together with the narrow angle of specular reflection of gloss papers, assures that almost all light reflected from the resin surface goes toward the opposite 45 deg. angle from the illuminant. Virtually all the light sensed by the spectro results from light reflected from the pigments themselves. Polarized light and filters doesn't change this because light reflected from the pigments randomizes the polarization. So there is little difference between M2 and M3 for glossy papers.

However, matte paper does not have a physically flat surface. Light that hits it at any angle is reflected back almost without any directional component. This includes both light that passes through the resin and is reflected from the pigments, and light that is reflected by the resin's surface. However, the light that reflects off the resin retains it's polarization (though not direction which is still randomized) and so can be strongly reduced by the M3 polarized filters.
Quote

3. I have found M3 to be less accurate in some colors than M2. For example, I get a more accurate match in the oranges with the M2 profile vs. M3. I cannot pin down why this is the case, except to say that the polarisation is having some sort of effect.

Very true, This can be easily demonstrated by printing a Colorchecker image using Abs. Col. on the same matte paper using M2 profiles and M3 profiles then comparing them to an actual colorchecker.

The M3 printed colorchecker will be significantly desaturated compared to the M2 print and the M2 print will match an actual Colorchecker more closely. Also, the darker M3 print neutral CC patches will be somewhat lighter with the darkest (L=20) patch being the lightest. Very similar to the effect of BPC. in Rel. Col.
Quote

4. All of the above are repeatable in multiple tests with the same results.

A few other notes: I have found the Xrite ISISXL2 produces better profiles when you select 'Colourful' and not the default. The gamut improves. And always select 'Best / Highest Quality.

The Colorful option only affects Perceptual. It has no effect on gamut which requires a colorimetric process. Rel. Col. and Abs. Col. are not changed by the Perceptual sliders.

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Josh-H

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #8 on: December 26, 2018, 07:10:51 pm »

Quote
The Colorful option only affects Perceptual. It has no effect on gamut which requires a colorimetric process. Rel. Col. and Abs. Col. are not changed by the Perceptual sliders.

Thank you - I did not know that.
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Alan Goldhammer

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #9 on: December 27, 2018, 08:27:21 am »

So if I am understanding Josh's points, M3 profiles have a lot to offer for B/W prints as more shadow detail is evident but such profiles are not as good for color printing because of color accuracy.  What I'm not clear about is the role of Black Point Compensation.  PS allows one to turn this on/off but in LR it is always on.  Given the following statement, "...However, if you turn on Black Point Compensation when you make a print with an M2 profile on matt paper the shadow detail results are identical to M3 printed without BPC turned on...", printing from LR should show a difference in prints from LR on the same paper using the two differing profiles, correct???  Some of this is counter intuitive as measurements are always different from visual acuity in terms of what the actual black represents.
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Mark D Segal

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #10 on: December 27, 2018, 08:49:33 am »

So if I am understanding Josh's points, M3 profiles have a lot to offer for B/W prints as more shadow detail is evident but such profiles are not as good for color printing because of color accuracy.  What I'm not clear about is the role of Black Point Compensation.  PS allows one to turn this on/off but in LR it is always on.  Given the following statement, "...However, if you turn on Black Point Compensation when you make a print with an M2 profile on matt paper the shadow detail results are identical to M3 printed without BPC turned on...", printing from LR should show a difference in prints from LR on the same paper using the two differing profiles, correct???  Some of this is counter intuitive as measurements are always different from visual acuity in terms of what the actual black represents.

I've explored this issue in some detail in my recent review of Red River's new Palo Duro Fine Art Smooth paper, because the Red River profile is a Chromix-supplied M3. You may wish to have a look there, also paying attention to the short Annex, and see whether this helps. There is a fundamental problem talking about "what the actual Black represents", because one needs to define the meaning of "actual" and the context for "represents". :-) The kind of analytics I did cannot be handled in Lr, so I did it all using Photoshop where one has more fulsome control over the relevant variables.
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Mark D Segal (formerly MarkDS)
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Alan Goldhammer

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #11 on: December 27, 2018, 09:11:14 am »

Mark, I read the review when you posted it and again this morning.  It's difficult reading some of the graphs that you present as they cannot be enlarged and I cannot read some of the small print or the axes.  I understand that the examination of the profiles reveals quite different gamuts and that this is a result of using polarized light.  However, and this is the big point I'm trying to grasp, the printed black point is what it is regardless of how one is making a measurement.  When I profile matte papers using my i1Pro and ArgyllCMS I routinely get a black point in the range of L* 15-18 depending on the paper for my Epson 3880.  If I had access to a Barbieri I could get a reading showing a "much deeper black point" even though the actual printed black has not changed.  It is the extension of the B/W range that permits a better gradation of shadow details as the profile is not compressed (I'm curious about how many B/W patches Chromix use in their profiling).

I get that you did a lot of the analysis in PS because of increased control over some variables.  However, most of us print from LR where these kinds of controls are absent.  Most of this is academic for me as I don't use Red River matte paper and don't have the hardware or software to prepare an M3 profile for the papers I use.  I'm also surprised by the high dE values posted in the sidebar at the bottom of the article.  I would have to go back and double check some of my profiling but IIRC, I don't get anywhere near that high a deviation using ArgyllCMS.
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Mark D Segal

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #12 on: December 27, 2018, 01:42:28 pm »

Alan, I wasn't aware of a reading difficulty with the graphs because on my PA272W display I can moderately magnify the material on the website and read everything clearly enough; however I can provide you what will be perfectly readable graphs off line if you send me a PM advising which.

I don't think the use of Argyll would make any significant difference to anything I am reporting here. When I test my own profile (made and tested with i1Pro2/i1Profiler) the average dE was 0.7, which is pretty darn good. The high dE readings we are seeing here is also for me a unique outcome that I have not encountered nearly to this extent with the many paper/profile combinations I've been testing.

As for how we print ordinary photographs, yes I agree - making prints out of LR one would be using Relative or Perceptual Rendering Intent and Lightroom handles BPC under the hood. One can replicate this exactly in Photoshop. LR has no Absolute Rendering Intent, which one needs for testing accuracy, so that is why I don't test out of LR.

We have two items at play determining Black shading appearance: the Maximum Black and the shape of the tonal rendition above it. The article demonstrates that the type of profile affects the shape of the quarter-tone rendition down to the maximum Black that the paper/printer combination can reflect. An M3 profile provides for more tonal separation in the quarter-tone range of a matte paper than we get from conditions M0/M1/M2. Turning to the Maximum Black point, if you examine Figure SB2 in the sidebar, you will see that Maximum Black only deviates from c. L*20 in the condition where one measures the Black patch with a spectro and software wherein M3 is enabled. In that one condition, the statistical value of Black is down at L*1. However, when you make a print with that profile and look at it, the printed Black looks more like L*20. The two lower panels of Figure SB2 are in Relative Intent with BPC, so they would predict outcomes printing from Lightroom with Relative Intent selected. Maximum Black should look similar whether using an M0 or M3 profile, but with somewhat more distinct tonal separation above that using the M3 profile. Perhaps we are saying the same thing! :-)
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Alan Goldhammer

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #13 on: December 27, 2018, 03:32:57 pm »

In that one condition, the statistical value of Black is down at L*1. However, when you make a print with that profile and look at it, the printed Black looks more like L*20. The two lower panels of Figure SB2 are in Relative Intent with BPC, so they would predict outcomes printing from Lightroom with Relative Intent selected. Maximum Black should look similar whether using an M0 or M3 profile, but with somewhat more distinct tonal separation above that using the M3 profile. Perhaps we are saying the same thing! :-)
Yes, I think we are.  The profile analyses are interesting but it's the print output that's most important.  I've no doubt that monochrome prints might benefit from this type of profile approach but color printing, not so much. 
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Rainforestman

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #14 on: January 17, 2019, 10:38:04 pm »

Quote
1. The angle and position of the polariser in the Barbieri is hyper critical to the results. shifting it even a fraction of a mm makes a very noticeable difference in the results. Given how critical it is there really should me a micrometer for moving the polariser and there isn't. It has to be done by trial and error and is extremely time consuming to get right.

Josh - the polariser for the Barbieri LFP S3 has a pin on the polariser and a registration socket on the spectrometer that the pin docks into.  It clicks into place magnetically and snugly without any play.  It can't rotate and should be in perfect alignment every time.  (see attached photos).

I wonder if there was something wrong with the polariser on the Barbieri LFP S3 that you tried - maybe it had a missing registration pin or wasn't a genuine filter?

Cheers,


Neil


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narikin

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #15 on: January 18, 2019, 10:29:03 am »

As the instigator of this thread - (who has quietly read each post as it comes in) - thank you all for your informative replies. I learn a lot on the 'Color Management' sub-forum, and am very appreciative.

I'll never know half the stuff you've already forgotten, but the helpfulness and willingness to share expertise is very refreshing, especially in these divisive times. Thank You.
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Josh-H

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #16 on: January 18, 2019, 04:01:47 pm »

As the instigator of this thread - (who has quietly read each post as it comes in) - thank you all for your informative replies. I learn a lot on the 'Color Management' sub-forum, and am very appreciative.

I'll never know half the stuff you've already forgotten, but the helpfulness and willingness to share expertise is very refreshing, especially in these divisive times. Thank You.

Thank you - I believe the pin is missing on the Barbieri I have access too.. I will look into getting a replacement. Thank you.
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Josh-H

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #17 on: January 19, 2019, 03:26:41 pm »

Josh - the polariser for the Barbieri LFP S3 has a pin on the polariser and a registration socket on the spectrometer that the pin docks into.  It clicks into place magnetically and snugly without any play.  It can't rotate and should be in perfect alignment every time.  (see attached photos).

I wonder if there was something wrong with the polariser on the Barbieri LFP S3 that you tried - maybe it had a missing registration pin or wasn't a genuine filter?

Cheers,


Neil

Neil, the Barbieri I have been using does not have this registration pin.. perhaps this was added in the newer model? I spoke with a colleague who also has one in Sydney and his does not have it either.
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Steve Upton

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #18 on: January 23, 2019, 04:04:59 pm »

2. ...... However, if you turn on Black Point Compensation when you make a print with an M2 profile on matt paper the shadow detail results are identical to M3 printed without BPC turned on.

I respectfully disagree. Perhaps I'm reading this response incorrectly but if you could simply use BPC instead of M3 measurements, then why would anyone bother with M3 measurements?

M3  / polarized measurements allow the instrument to do a better job discriminating between shadow colors. As a result (when used with the right substrates) the profiles gain access to better detail in the shadows.

This is much different than simply turning on BPC...


.....  I've no doubt that monochrome prints might benefit from this type of profile approach but color printing, not so much.

Again, I disagree. The dimension we're primarily addressing here is Lightness, rather than saturation or hue.

If an image has significant detail in the shadows and the first-surface reflections from the substrate are interfering with the instrument's ability to measure, M3 measurements can help. Whether or not it's a color or monochrome print isn't relevant in our experience.

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Doug Gray

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Re: Barbieri M3 Polarized profiles - worth it for PK papers?
« Reply #19 on: January 23, 2019, 05:28:04 pm »

Quote
My final conclusions on M2 vs. M3 are that if you print with an M2 profile you must use BPC to get good shadow detail. With M3 you dont need to turn on BPC. However, I find the M2 profile more accurate in certain colors than the M3.
I respectfully disagree. Perhaps I'm reading this response incorrectly but if you could simply use BPC instead of M3 measurements, then why would anyone bother with M3 measurements?


I don't. His observations concur with the physics differences between M2/M3 on matte.


Quote


M3  / polarized measurements allow the instrument to do a better job discriminating between shadow colors. As a result (when used with the right substrates) the profiles gain access to better detail in the shadows.

Yes, M3 can produce better appearing dark shadow and dark color gradients on matte. Especially under strong illumination with large, dark areas. This is because there is better utilization of the M3 profile 3D grid as well as more value separation between the dark patch, profile target measurements.

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