Luminous Landscape Forum
Raw & Post Processing, Printing => Printing: Printers, Papers and Inks => Topic started by: rasworth on March 11, 2018, 11:55:16 am
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Needed an inexpensive 17"x25" photo paper, purchased a box of Red River UltraPro Luster 300. Checked it with the black light, as expected had significant OBA content.
I created a profile using I1Profiler, auto generated 1215 patch set, and my I1Pro UVCut. Profile checked out ok, satisfactory test print and good match via Photoshop softproofing. White point per ColorThink Pro is L*a*b* = 94.1,-.8,-.6.
So here's the question - the white point after supposedly filtering out the uv OBA excitation is close to neutral. Why is the manufacturer using OBAs at all? Is there some magic outside of the uv excitation that contributes to the whiteness, or has the manufacturer decided really bright is better than white?
I did a quick spot measurement with my I1Pro Normal, L*a*b* = 95.6,.9, -8.0, the OBAs are obviously there and kicking.
Richard Southworth
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b* of -8.0 is hardly near neutral - it's quite bluish. But to address your question: manufacturers include OBA in some of their papers for the same reason that soap companies sometimes put whiteners in laundry detergent - it's for those "whiter whites" that large numbers of consumers like.
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I understand b* = -8.0 is quite bluish, but -.6 is not, and that is the result using the uv cut instrument. So can we assume the base "whiteness" of the paper before adding OBAs is reasonably neutral? Or another way of looking at it, some years later after the OBAs have lost their uv excitation capability will the paper appear neutral instead of yellowish?
Richard Southworth
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I understand b* = -8.0 is quite bluish, but -.6 is not, and that is the result using the uv cut instrument. So can we assume the base "whiteness" of the paper before adding OBAs is reasonably neutral? Or another way of looking at it, some years later after the OBAs have lost their uv excitation capability will the paper appear neutral instead of yellowish?
Richard Southworth
Hard to say. OBAs themselves can become yellowish with age. So you might see the paper white's b* shift slightly into positive territory after many years and exposure to daylight.
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I understand b* = -8.0 is quite bluish, but -.6 is not, and that is the result using the uv cut instrument. So can we assume the base "whiteness" of the paper before adding OBAs is reasonably neutral? Or another way of looking at it, some years later after the OBAs have lost their uv excitation capability will the paper appear neutral instead of yellowish?
Richard Southworth
No - not to my thinking anyhow. a*-0.6 is quite neutral, but it's the whole reading that matters, not just one component. I don't think you can assume the paper will look neutral once the OBA fades, nor does one know anything about the time path of fading or whether it fades evenly - maybe Aardenburg has some data on this you could check?
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I guess I was assuming most photos would be mounted with low uv exposure. If true, then the fade curve wouldn't matter much, as long as aging caused a loss of emissivity without an actual OBA reflected color change. However if the OBA component actually yellows then all bets are off. I checked earlier on Aardenburg, didn't come up with anything.
Richard Southworth
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I understand b* = -8.0 is quite bluish, but -.6 is not, and that is the result using the uv cut instrument.
It isn't but then if you use UV Cut, the instrument is blind to the reality of the paper itself.
http://digitaldog.net/files/24TroubleWithFWAs.pdf (http://digitaldog.net/files/24TroubleWithFWAs.pdf)
Placing a UV-blocking filter over the spectrophotometer is a partial solution, but can be an ineffective fix. UV-blocking filters can block all but the visible light spectrum, but you get the best color matches when the print-viewing conditions have the same amount of UV as the light source in the spectrophotometer that’s used to build the paper profile. Filtering UV is like correcting one error by introducing another.
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My viewing environment is LED throughout the house, so uv cut seems to match up well. I understand the exposure when viewing in other environments that might not be so uv minimal.
Richard Southworth
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My viewing environment is LED throughout the house, so uv cut seems to match up well. I understand the exposure when viewing in other environments that might not be so uv minimal.
Richard Southworth
For LED lighting, uV cut (M2) is the best choice. There is virtually no uV in most LED lights. In fact, ColorMunki and iSis, both use a white LED for the M2 measurements. Since there is so little uV, neither needs a uV cut filter.
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My original question, why did the manufacturer add OBAs to a paper that is apparently close to neutral, is probably not answerable. A more reasonable question is given the results of the uv cut based profile, l*a*b* = 94.1,-.8,-.6, is this a reasonable paper to use in a low uv environment, and expect to have stable image on a near neutral surface for some number of years. The closest match in Aardenburg for my printer, an Epson 3880, is Epson Ultra Premim Photo Paper Glossy, which seems to be holding up ok (listed as high in OBAs). I understand that Epson may well use a different formulation than Red River.
The paper, Red River UltraPro Luster 300, is slightly heavier than some of its competition, and the large sheets handle well without kinking. Initial test printing with the aforementioned profile is positive. Given that it will be displayed in low UV environments the changing uv induced emissivity should not be an issue. There is the possibility the OBA compounds themselves will yellow, I'm willing to live with that exposure given that I haven't seen much of this phenomena with modern papers.
Richard Southworth
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My original question, why did the manufacturer add OBAs to a paper that is apparently close to neutral, is probably not answerable.
Mark answered didn't he? It is only 'neutral' in those Lab values if you accept what isn't being measured.
A more reasonable question is given the results of the uv cut based profile, l*a*b* = 94.1,-.8,-.6, is this a reasonable paper to use in a low uv environment, and expect to have stable image on a near neutral surface for some number of years.
No due to instability of OBAs. Best to avoid them if this is a concern.
There is the possibility the OBA compounds themselves will yellow, I'm willing to live with that exposure given that I haven't seen much of this phenomena with modern papers.
Wait ;D
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Andrew,
I'm assuming "what isn't being measured" are the visible blues generated by the uv excitation. I don't see an inconsistency with combining a uv cut m2 profile with a viewing environment with little or no uv present, and therefore labeling the paper as near neutral without OBA action.
Richard Southworth
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I would not assume that the paper base without OBA is neutral. Usually it is warm, add enough OBA and it becomes cool. Less expensive than starting from a neutral base paper. That the profile shows a near neutral white point is not just the result of a UV cut Spectrometer, it includes the software extrapolation to say 380nm based on the measurements above 400/420nm. There are often some arbritrary things done in that spectral range. Numbers just copied downwards happens too.
Enough Aardenburg-Imaging results that show shifting to neutral in time of OBA content papers is not always the case. Either the base was never neutral and/or the OBAs degraded to a stain.
http://forum.luminous-landscape.com/index.php?topic=53690.20
Ernst, op de lei getypt.
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Andrew,
I'm assuming "what isn't being measured" are the visible blues generated by the uv excitation.
What isn't being measured is what's cut, so yes. It's there. We may see it and maybe differently than the Spectrophotometer and based on the illuminants (there is the one in the Spectrophotometer and one we use to view the prints and they often differ).
Make a profile each way. Examine the soft proof using an Absolute Colorimetric intent and you'll usually see quite a large visual difference between the two profiles. But as I pointed out earlier, there are no rules. If you have a Spectrophotometer that can measure both ways, do so and build two profiles and see which you prefer under your own lighting. But don't assume that because you have a Bstar value that isn't large in the negative direction if you will, that there are no OBAs when the measurement is made to cut them out!
The big issue I see with OBAs is that the print can change over time due to them and I suspect that's not desirable for many.
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I'm not assuming there are no OBAs, rather that the effect of the OBAs is minimized. So yes, the OBAs are still there, but if they are not emitting do they have any other effect? We need a paper chemistry type to answer that one.
It's easy to state we should avoid OBAs, and I use papers that don't contain any. However some people prefer the brighter whites, and the resin coated papers are usually cheaper. I have profiled several papers with OBAs with an uv cut i1Pro, and they generally end up b*=-2 or "more", i.e. once the OBA is negated the resulting white point tends to yellow. This paper struck me as unusual because the m2 results ended up close to neutral, and in a uv free viewing environment the whites are still "whiter" than the OBA free papers.
Richard Southworth
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I'm not assuming there are no OBAs, rather that the effect of the OBAs is minimized.
The bit about assuming (sorry) is simply based upon what you read via Lab values from a UV cut reading. And yes, it is easy to state you should avoid OBAs, even detecting them can be tricky although a good ol' black light works well. Bigger point is, if you can measure with UV cut and UV included, do it and build two profiles, then test. Thankfully it's affordable to do so these days. Back in the day, a Spectrophotometer that could read both was expensive and slow (I'm thinking of my old Spectrolino). Noisy too!
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Let me make sure I understand how an uv cut i1Pro operates - I "assume" the uv from the lamp is eliminated/attenuated, and therefore the reflection to the spectro would contain little or no content from the OBAs. Am I on track?
Richard Southworth
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Let me make sure I understand how an uv cut i1Pro operates - I "assume" the uv from the lamp is eliminated/attenuated, and therefore the reflection to the spectro would contain little or no content from the OBAs. Am I on track?
There's either a filter or no filter but let's just look at the results, not what is happening deep in the instrument.
I have Lab values from my iSis using M0 and M2 and I'm measuring Epson's Prem Luster paper which has OBAs. M0 the bstar reads -6.72. M2 it measures 2.5. One tells us something about the OBA's while the other isn't really true because again, it isn't measuring without the UV Cut filter. That is why I wrote: if you use UV Cut, the instrument is blind to the reality of the paper itself.
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There's either a filter or no filter but let's just look at the results, not what is happening deep in the instrument.
I have Lab values from my iSis using M0 and M2 and I'm measuring Epson's Prem Luster paper which has OBAs. M0 the bstar reads -6.72. M2 it measures 2.5. One tells us something about the OBA's while the other isn't really true because again, it isn't measuring without the UV Cut filter. That is why I wrote: if you use UV Cut, the instrument is blind to the reality of the paper itself.
Whoops - this is getting a bit difficult, as double-negatives can be - maybe just at my age. Does your iSis work like the i1Pro2 using a dual scan mode to create the M2 condition? More generally how do you create the M2 data file? With M0 you get the kind of bluish reading we expect from Epson PLPP. Turning to the M2 reading, you say you don't trust it because "it isn't measuring without a UV cut filter." What does this mean - that it is measuring with a UV cut filter? Or measuring with a light source that doesn't excite the FBA? If so, I would expect something like the 2.5 because that M2 measurement is supposed to be neutralizing the OBA impact by not seeing or suppressing the UV - somehow. It's the "somehow" that I would emphasize here - seems that the 2.5 is an approximation, because the filtering may not be accurate. But give or take a bit, we should still expect an M2 b*reading considerably warmer than -6.7 if it's counteraction of the UV is "in the ballpark" - right? If so, the M2 reading may be closer to eventual paper white (after OBA fading) than is the M0 reading, but we don't know how close. Am I making sense here?
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There's either a filter or no filter but let's just look at the results, not what is happening deep in the instrument.
I have Lab values from my iSis using M0 and M2 and I'm measuring Epson's Prem Luster paper which has OBAs. M0 the bstar reads -6.72. M2 it measures 2.5. One tells us something about the OBA's while the other isn't really true because again, it isn't measuring without the UV Cut filter. That is why I wrote: if you use UV Cut, the instrument is blind to the reality of the paper itself.
The basic problem with OBA laden papers is that it will look different depending on the uV content of whatever illuminant you choose to display or show the print. Change it and the print can appear different. There are other issues as well such as metameric shift which is especially a problem for cheap LED and fluorescent lighting but one thing at a time.
Whether profiles using M2 are "true" or not depends on whether the illuminant the paper is viewed under has uV or not. If not, it IS true. The problem is determining whether the light you are viewing the print has uV, and if it only has some, which a lot of regular incandescents do, whether M2, M1, or M0 is the closest match to the level of uV from it.
There is a fairly simple say to determine this with OBA papers.
Measure the Lab value of the white patch on your colorchecker card.
Create a patch in Photoshop and it has to be in Photoshop or some other program that allows Abs. Col. printing. Fill the patch with Lab=(Colorchecker white patch). Then print the patch using each of the three M0, M1, and M2 profiles made for the paper using Absolute Colorimetric. It's easy to print these on the same sheet by positioning them differently across the paper's top and making 3 prints on the same sheet.
Now, cut the patches off so you don't see any surround and have three patches. Good idea to mark the patches with M numbers to keep track.
View these patches against the Colorchecker under the illuminant of interest (home lighting, display lighting, outdoor lighting, etc).
Then just use the Mn Profile that most closely matches.
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I guess that's where we disagree - I don't consider the results from stimulating the paper with a uv free source any less real than stimulating with uv included. Both results are valid if they reflect real viewing conditions, and if those viewing conditions can be practically selected. I practiced for several years only using a normal i1Pro, and often had problems profiling OBA papers. I've been much more successful using the i1Pro uv cut for those papers. And for those of use still doing hand scanning it is significantly more work to scan with both instruments in order to compare profile results.
You measured Epson Prem Luster M0 b*=-6.72 and M2 b*=2.5. I measured RR UltraPro Luster M0 b*=-8.0 and M2 b*=-.6. I believe both M2 results are just as true as the M0 results, and equally useful. I agree that without the M0 measurements we wouldn't know anything about the OBA content, but that doesn't make the M2 measurements incomplete, they are sufficient to create a profile for use where the viewing conditions match, i.e. no uv.
Richard Southworth
Added by edit - I was answering Andrew, didn't realize other posts had occurred. BTW both of my instruments are i1Pro 1s, second generation.
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Whoops - this is getting a bit difficult, as double-negatives can be - maybe just at my age. Does your iSis work like the i1Pro2 using a dual scan mode to create the M2 condition? More generally how do you create the M2 data file? With M0 you get the kind of bluish reading we expect from Epson PLPP. Turning to the M2 reading, you say you don't trust it because "it isn't measuring without a UV cut filter." What does this mean - that it is measuring with a UV cut filter? Or measuring with a light source that doesn't excite the FBA? If so, I would expect something like the 2.5 because that M2 measurement is supposed to be neutralizing the OBA impact by not seeing or suppressing the UV - somehow. It's the "somehow" that I would emphasize here - seems that the 2.5 is an approximation, because the filtering may not be accurate. But give or take a bit, we should still expect an M2 b*reading considerably warmer than -6.7 if it's counteraction of the UV is "in the ballpark" - right? If so, the M2 reading may be closer to eventual paper white (after OBA fading) than is the M0 reading, but we don't know how close. Am I making sense here?
I believe all iSis scanners scan using M2 (uV cut) because they use a "white" led. Then they do a second scan, if selected, using uV only which they read and add in various amounts to generate spectra and Lab values for M0 and M1. The I1Pro 2 uses an incandescent lamp which reads M0. The second pass, if selected, activates a uV light only and reads the fluorescent response. It then calculates M2 and M1 from those.
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Yes Mark the Isis measured the row twice.
And observing OBAs is as simple as viewing it under a black light from the cool 1960s or a newer LED black light which are available for little money (you don’t have to own a spectrometer)
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I guess that's where we disagree - I don't consider the results from stimulating the paper with a uv free source any less real than stimulating with uv included. Both results are valid if they reflect real viewing conditions, and if those viewing conditions can be practically selected. I practiced for several years only using a normal i1Pro, and often had problems profiling OBA papers. I've been much more successful using the i1Pro uv cut for those papers. And for those of use still doing hand scanning it is significantly more work to scan with both instruments in order to compare profile results.
You measured Epson Prem Luster M0 b*=-6.72 and M2 b*=2.5. I measured RR UltraPro Luster M0 b*=-8.0 and M2 b*=-.6. I believe both M2 results are just as true as the M0 results, and equally useful. I agree that without the M0 measurements we wouldn't know anything about the OBA content, but that doesn't make the M2 measurements incomplete, they are sufficient to create a profile for use where the viewing conditions match, i.e. no uv.
Richard Southworth
Added by edit - I was answering Andrew, didn't realize other posts had occurred. BTW both of my instruments are i1Pro 1s, second generation.
The safest way to get a print profiled for more display conditions is selecting an OBA free paper and measure it with an UV enabled spectrometer then create the printer profile.
The second safest way is selecting an OBA free paper and measure it with an UV cut spectrometer. After that come the worst combinations. Starting with an OBA loaded paper like the one you have is asking for issues at some point. 99% of RC inkjet papers have OBA content, very few so little that it is no issue. The shift of the paper white in time can be caused by UV light, light, gasses like oxygen, ozone, dark storage after exposure. Framed behind plain glass the fluorescence effect already is reduced, behind UV blocking glass it is absent. Yet that does not mean the OBAs are totally free of degrading there. Display conditions vary and UV light may be part of it or not, either caused by daylight entering or not so good converted by fluorescents in the CFLs. In short it suffers more of changing conditions than paper without OBA does.
Since the introduction of OBAs in papers after WWII consumers are more and more used to a bluer white point where UV fluorescence adds brightness to the normal whiteness of papers. Paper manufacturers introduced the Brightness property where the blue part of the spectral range is used to measure the "light reflection", they promoted that Brightness property. Most RC paper bases used to apply inkjet coatings on are already containing OBA, the coating may contain them too. For an RC inkjet paper manufacturer it is harder to create a neutral paper without OBA that gives similar Lab L light reflection that papers with OBA can achieve by this physics trick. So when consumers like to get that OBA look and it is easier to make, you get the paper you have.
The spectral plot of a Red River paper close to your paper is attached together with some alternatives with lower OBA content. Your's is most likely a Mitsubishi manufactured type. The PIctorico one too but with less OBA and Red River has a similar one. The purple plot is one of the RC exceptions with almost no OBA, Epson Proofing White Semi-Matte. Little OBA in the paper base, plenty of other "normal" whitening agents aboard to flatten the spectrum reflected and no OBA in the inkjet coating. You probably will not like its texture and it looks warm despite being neutral in the CIE definition. The dot lines show the OBA as measured at the back of the paper (black underneath) so more or less the paper bases with OBA content they started with.
UV-cut spectrometer raw readings are massaged one way or another when printer profiles are created with them. The white point is not the white point when OBAs are activated nor is it the white point of the paper base as if no OBA was added at all, the created white point is a virtual one representing a generic neutral paper. As shown the brightness created by fluorescence can differ a lot between OBA containing papers yet near neutral white points are usual for the printer profiles created that way. From the left to 575nm an OBA effect could exist but goes unnoticed by spectrometers with UV cut lamps + UV cut sensors, depending on how flat the remaining reflected spectrum is a profile can be made but what is actually raw measured for some must be way warmer than neutral, red end high and steadily descending towards the blue side. In that sense the Lab a figure is more revealing when white point numbers are taken from profiles made that way, green/yellow reflection of that paper being low and measurable, you would expect a positive Lab a number there but it is slightly negative in your profile. Green plot lines representing your paper.
Although it starts from UV enabled measurements and aims at the estimation of the OBA effect, extrapolations included, this article is interesting to read. The attitude to declare UV cut measurements as dealing with the OBA paper content in practice is a false one, kind of ostrich head in the sand approach. Also notice that the estimation mentioned there improves when the non OBA reflection is already quite neutral, read "normal" whitening agents already created a flat spectrum without the OBA effect. Then the so called D50 measurement versus so called D50 viewing conditions and actual light sources used for both.
https://www.argyllcms.com/doc/FWA.html
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
March 2017 update, 750+ inkjet media white spectral plots
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Ernst,
Thank you for your reply. I have one minor disagreement - the paper with similar characteristics to RR UltraPro Luster (subject of my post) is RR UltraPro Satin, represented by the brick red line on your graph. The green line represents Arctic Polar Luster, which I also own and have profiled, and it is indeed a "hotter" paper with higher OBA content. Red River recommends using their UltraPro Satin profile with the UltraPro Luster paper.
So per your statement "The attitude to declare UV cut measurements as dealing with the OBA paper content in practice is a false one, kind of ostrich head in the sand approach", what would you recommend as an alternative? I own two instruments, both i1Pros, one normal and one uv cut. I've had more visually pleasing results building profiles for OBA papers using the uv cut instrument. In the old days using a normal instrument with Profilemaker, even though they claimed to sense and correct, I was always fighting a tendency for the resulting print to tend toward yellowish. I don't have that issue with the uv cut instrument.
Richard Southworth
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I guess that's where we disagree - I don't consider the results from stimulating the paper with a uv free source any less real than stimulating with uv included.
Look at the numbers man! Look at the name (UV CUT).
Both results are valid if they reflect real viewing conditions, and if those viewing conditions can be practically selected.
There's no viewing conditions yet. Just numbers from the Spectrophotometer. And I said, and I'll repeat: there are no rules! If you can you should measure both ways and build two profiles do so. Then make prints and test. Enough said.
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Ernst,
Thank you for your reply. I have one minor disagreement - the paper with similar characteristics to RR UltraPro Luster (subject of my post) is RR UltraPro Satin, represented by the brick red line on your graph. The green line represents Arctic Polar Luster, which I also own and have profiled, and it is indeed a "hotter" paper with higher OBA content. Red River recommends using their UltraPro Satin profile with the UltraPro Luster paper.
So per your statement "The attitude to declare UV cut measurements as dealing with the OBA paper content in practice is a false one, kind of ostrich head in the sand approach", what would you recommend as an alternative? I own two instruments, both i1Pros, one normal and one uv cut. I've had more visually pleasing results building profiles for OBA papers using the uv cut instrument. In the old days using a normal instrument with Profilemaker, even though they claimed to sense and correct, I was always fighting a tendency for the resulting print to tend toward yellowish. I don't have that issue with the uv cut instrument.
Richard Southworth
Richard, if your UV-enabled spectrometer, i1Pro Normal as you call it, is worth its money and it reads Lab 95.6 0.9 -8.0 then that paper has more relation with the RR Artic Pro Luster that my UV-enabled i1Pro measures as Lab 95.8 1.4 -9.8. The RR Palo Duro and UltraPro Satin have respectively a Lab b -3.4 and -3.1 here. All the RR RC papers I measured fall in these two classes. That has been measured some time ago though. Checking all the 300 grams RC versions that I have and anything near b -8.0 gives me this screengrab, does not change my opinion on what is happening with the numbers. RR may purchase from Felix Schoeller or have the same supplier Moab uses. Something is odd if RR says the OBA content is low, UltrPro Satin class, and you measure Lab b -8.0
BTW that -.5 instead of -0.5 use is highly confusing for me, could be my glasses or my EU metric background.
Use a low OBA content RC paper, measure it with both spectrometers. Make two profiles, greys neutral, compare. Make another two profiles with the greys adapted to the paper white, compare the four. Not familiar with i1Profiler but settings like that should be aboard. Then check the white point numbers again.
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
March 2017 update, 750+ inkjet media white spectral plots
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Red River doesn't claim low OBA for UltraPro Luster, just that it matches UltraPro Satin. The confusion may lie in the fact that the current version of UltraPro Satin is 4, considerably "whiter" than the older versions, which may be what you measured. A RR support person told me that their Palo Duro Satin is more or less equivalent to the older versions of UltraPro Satin, considerably warmer than today's version.
And I'll try to keep the 0 in front, i.e. -0.x.
Richard Southworth
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Ran a non-quantitative test with the black light, RR Arctic Polar Luster on the left, and the subject of my post, RR UltraPro Luster 300, on the right. You can draw your own conclusion as to relative OBA content. I don't have any UltraPro Satin for comparison.
Richard Southworth
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Aardenburg Imaging & Archives reports a "UV fluorescence" figure in each test report and in the database list as well. We use the following criteria to determine if the paper has no OBA, low OBA, moderate OBA, or High OBA content.
No OBA: absolute value of M0-M2 readings measured b* difference <0.3
Low OBA: absolute value of M0-M2 measured b* difference = 0.3 to 2.5
Medium OBA: absolute value of M0-M2 measured b* difference = 2.5 to 5.0
High OBA: absolute value of M0-M2 measured b* difference ≥5.0
As a general rule of thumb, papers with no or low OBAs test better in Aardenburg light fade tests, i.e not contributing much in the way of highlight color changes which contribute adversely to the overall Aardenburg Conservation Display rating for a given printer/ink/media combination.
Medium OBA content starts to impact the score and undermine the inherent goodness of any reasonably light fast ink set performance.
High OBA content inevitably and significantly undermines the inherent light fade resistance of any decent dye-based or pigment based ink set.
Lastly, the "yellowing" which accrues due to OBA burnout is not just about the loss of fluorescence causing the paper to revert to its underlying "natural" UV filtered media whitepoint. It's also about the fact that the degradation bi-product(s) of the OBA burnout don't necessarily remain colorless over time. The faded OBAs typically produce an additional metastable (i.e., light- bleachable but not stable) yellowing/discoloration component when retired to dark storage (or when displayed under low to moderate illumination levels). This additional staining can double or triple the amount of discoloration observed by the viewer merely due to loss of fluorescence. I've seen degraded whitepoint values of high-OBA content papers climb above b*=20.0 for media stored in the dark after 100 Mlux hour accumulated light exposure for an additional year or more and then remeasured.
Moral of the story: Media with high OBA content like many of today's RC photo media are well matched to traditional dye-based photos where the fading of the dyes typically occurs faster than the degradation of the RC photo paper. However, with modern synthetic dye or pigmented inkjet systems, today's RC photo inkjet papers aren't stable enough in their own right to achieve what the latest OEM inkjet inks deserve in terms of a stable paper to maintain their higher levels of light fade resistance over time.
cheers,
Mark
http://www.aardenburg-imaging.com
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Mark A.,
Thank you for your contribution to this thread. I noted in your test results for the Epson 3880 you had data for Epson Ultra Premium Glossy, which has an OBA high rating. Have you seen yellowing as you described for this paper? Have you detected any awareness/concern about this issue by paper manufacturers, i.e. are they developing any new less susceptible OBA compounds?
Richard Southworth
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Ernst,
Decided to "cheat" on my homework assignment, and just do spot measurements with Measure Tool (see attached image).
First I measured Moab Juniper Baryta, claimed to be OBA free, with both of my i1Pro instruments:
Normal l*a*b* = 97.2, -0.6, 2.5
uv cut l*a*b* = 97.2, -0.4, 2.8
I consider this to be a reasonable match between the two instruments.
Now the OBA laced Red River UltraPro Luster 300:
Normal l*a*b* = 96.3, 1.0, -7.6
uv cut l*a*b* = 95.6, -0.7, -1.0
No surprises I believe.
Interestingly to me, test prints from my 3880 on these two papers, viewed in my normal environment which I believe is uv minimal, appear very similar. The main difference is the slightly creamier white of the Moab. I'd say it was a toss-up, except of course for the over 2 to 1 cost difference. Profiles were constructed per my usual approach, uv cut for OBA paper and normal for the OBA-free paper.
One last question - do the OBA compounds degrade as fast in a low uv environment, both emissivity and yellowing?
Richard Southworth
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Mark A.,
Thank you for your contribution to this thread. I noted in your test results for the Epson 3880 you had data for Epson Ultra Premium Glossy, which has an OBA high rating. Have you seen yellowing as you described for this paper? Have you detected any awareness/concern about this issue by paper manufacturers, i.e. are they developing any new less susceptible OBA compounds?
Richard Southworth
I'm working on an Aardenburg light fade database II which will integrate both light fade and dark storage combined results. It's definitely a work in progress, but once the dark storage yellowing issues are integrated into the overall test result, the current Epson Ultra Premium luster and glossy papers are going to rank among the worst RC inkjet photo papers on the market. Canon RC photo papers (Luster and Semigloss pro, but not Platinum) will have about half of the light-induced post exposure staining as the Epson papers.
Are the manufacturers working on improvement? Hell no! The customer can't see the problem when looking at initial image quality, so the customers aren't complaining...yet! But once the yellowing problems begin to be talked about in forums like LULA's printers and printing forum, I'm optimistic that media longevity improvements will be made. Epson's Proofing Paper White Semimatte is a good example of a low OBA resin coated (RC) paper exhibiting far less yellowing/discoloration over time. That said, EPPWSM does not have a typical "photo" surface texture that will appeal to all RC photo paper enthusiasts, but it would be easy enough for Epson to specify an "Epson Premium Luster Natural" RC photo paper with all of the good longevity characteristics of Epson Proofing Paper White Semimatte. The printmaking community just has to insist that the manufacturers do better!
cheers,
Mark
http://www.aardenburg-imaging.com
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One last question - do the OBA compounds degrade as fast in a low uv environment, both emissivity and yellowing?
Richard Southworth
Not as fast, but fast enough. Blue wavelength radiation has enough energy to fade OBAs, dyes, and pigments as well... the UV wavelengths from direct sunlight striking a print on the wall typically contributing to 2-3x increased fade rate, but again, UV excluded light still has plenty of energy to fade artwork hanging on the wall. Many framers say UV filtered glazing stops fading. That's wrong. The truth is that it typically slows the process 2-3X, which is, of course, significant, but lowering the light level on display 2-3x is also incredibly trivial. So, in the long run, print collectors should worry far more about light intensity on display (it can routinely vary 10-100x or more) than on the choice of glazing which frames their prints on display.
cheers,
Mark
http://www.aardenburg-imaging.com
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The printmaking community just has to insist that the manufacturers do better!
cheers,
Mark
http://www.aardenburg-imaging.com
And/or just focus one's purchases on papers that meet one's taste in respect of OBA content. For example, Epson Legacy Platinum has no OBA (they and my spectro indicate) and it does have the the kind of luster/gloss surface good for providing wide gamut, High DMax results using PK ink. Ilford Gold Fibre Silk has much less OBA than Epson PLPP (according to my spectro) so it should do much better than PLPP in your combined testing. Hahn Photo Rag Baryta is similar to Legacy Platinum. So there are options on the market now to meet quite a variety of tastes in the matter.
Now, when these discussions of OBA arise, I like to take a peak through "history" to see what I find. You may remember that back in the day when Epson first made archival inkjet printing on the desktop possible with the P2000 printer, the choice of papers was very limited compared with what we now have. In those days, (year 2000) I printed on PLPP and Enhanced matte - EMP (both Epson). I still have those prints, so 18 years of inkjet history. I just now made some measurements of paper white (b*) and here's what I got:
PLPP from year 2000;
M0: -2.3
M1: -2.9
M2: -0.11
PLPP from an early 2017 package:
M0: -3.9
M1: -4.8
M2: -0.7
This would seem to suggest that (a), yes the OBA presence is considerable in this paper (as we always knew) and (b) either the recipe changed or the OBA in the old stock has faded, given the less negative numbers in that series compared with the recent ones. There is no appearance of yellowing, and the paper white looks uniform, but if this is a trajectory and it carries on for another couple of decades, one may well be telling a different story - one about paper white starting to look yellowish.
I also measured the 18 year old EMP, and here's what I got:
M0: -0.8
M1: -2.7
M2: +5.7
We also know this paper was/is choc-a-bloc OBA loaded. Unfortunately I don't have any current stock as a comparator. But the old stuff again, still looks OK, there is no visual appearance of uneven OBA fading; however that M2 result is a bit worrisome - very warm, perhaps indicating that this paper will eventually look rather yellowish.
My visual references are under Solux 4700.
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Now, when these discussions of OBA arise, I like to take a peak through "history" to see what I find...
Your history sounds a lot like dark storage in enclosures/document storage boxes and/or cabinets for the last couple of decades where both light exposure and Ozone exposure are very low. In that context OBAs hold up quite well. It's display environments and subsequent storage environments after time on display where the trouble arises.
kind regards,
Mark
http://www.aardenburg-imaging.com
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Your history sounds a lot like dark storage in enclosures/document storage boxes and/or cabinets for the last couple of decades where both light exposure and Ozone exposure are very low. In that context OBAs hold up quite well. It's display environments and subsequent storage environments after time on display where the trouble arises.
kind regards,
Mark
http://www.aardenburg-imaging.com
Ah sorry - good catch - I forgot to mention that. You are correct. The prints are bound into books that remain shut (and for this set, slip-cased) on a shelf. So very little exposure. But even so there is evidence here of OBA fading, wouldn't you say?
The other thing that's very noticeable is how far inkjet printing has advanced since then - the improvements have been on the whole gradual from one version to the next, but add them all up and it's just a sea-change in vibrancy, black points, gamut, whatever.
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I also measured the 18 year old EMP, and here's what I got:
M0: -0.8
M1: -2.7
M2: +5.7
We also know this paper was/is choc-a-bloc OBA loaded. Unfortunately I don't have any current stock as a comparator. But the old stuff again, still looks OK, there is no visual appearance of uneven OBA fading; however that M2 result is a bit worrisome - very warm, perhaps indicating that this paper will eventually look rather yellowish.
My visual references are under Solux 4700.
Interesting. I once left a printed sheet of EMP I had done some test printing on next to a book after I was finished with it. Some years later I dug out the book, noticed the paper edge that was not covered by the book had significantly yellowed. I didn't measure it but would guess b* had increased well over 5. I haven't seen significant shifts for paper kept in their boxes. Mark A's comment that uV yellows 2-3 faster than regular light sounds right.
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...The other thing that's very noticeable is how far inkjet printing has advanced since then - the improvements have been on the whole gradual from one version to the next, but add them all up and it's just a sea-change in vibrancy, black points, gamut, whatever.
And yet, inkjet prints are still highly fragile when compared to other traditional photographic processes in numerous ways, i.e., abrasion resistance, gas fade resistance, humidity resistance for dye-based systems, sensitivity to VOCs, even light fade resistance with poor inks or media, etc. There's much room for improvement, so why should we give manufacturers of inkjet printers, inks, and/or media a free pass nowadays? Better to keep up the customer pressure for improvement alive and well, IMHO.
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... But even so there is evidence here of OBA fading, wouldn't you say?
Yes, most likely ozone attack coming in from the edges of a photo album type of storage condition. OBAs are extremely sensitive to ozone when located in microporous ink receptor coatings. OBA impregnated papers can fade in OBA fluorescence, especially around the paper edges, in just a matter of days due to ozone incursion.
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I'm working on an Aardenburg light fade database II which will integrate both light fade and dark storage combined results. It's definitely a work in progress, but once the dark storage yellowing issues are integrated into the overall test result, the current Epson Ultra Premium luster and glossy papers are going to rank among the worst RC inkjet photo papers on the market. Canon RC photo papers (Luster and Semigloss pro, but not Platinum) will have about half of the light-induced post exposure staining as the Epson papers.
Are the manufacturers working on improvement? Hell no! The customer can't see the problem when looking at initial image quality, so the customers aren't complaining...yet! But once the yellowing problems begin to be talked about in forums like LULA's printers and printing forum, I'm optimistic that media longevity improvements will be made. Epson's Proofing Paper White Semimatte is a good example of a low OBA resin coated (RC) paper exhibiting far less yellowing/discoloration over time. That said, EPPWSM does not have a typical "photo" surface texture that will appeal to all RC photo paper enthusiasts, but it would be easy enough for Epson to specify an "Epson Premium Luster Natural" RC photo paper with all of the good longevity characteristics of Epson Proofing Paper White Semimatte. The printmaking community just has to insist that the manufacturers do better!
cheers,
Mark
http://www.aardenburg-imaging.com
Other than the Canon’s, are there any others that have better characteristics which you could share with us?
And what time frame are we looking at for the degradation?
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Other than the Canon’s, are there any others that have better characteristics which you could share with us?
And what time frame are we looking at for the degradation?
20 Megalux hours of light exposure is more than enough exposure to reveal OBA light fading and post-exposure dark storage issues, albeit higher exposure doses increase the magnitude of the problem. 20 Mlux hours equals twenty years on display at an average display illumination level of 228 lux for 12 hours per day, or just 10 years on display if using the Wilhelm extrapolation assumption for light levels at 450 lux for 12 hours per day. Maybe that's good enough for some folks, but why use a high quality pigmented inkset that can be fade resistant for 100 Mlux hours on display or more if the paper is going to let you down in 20 Mluxhrs? That's the crux of it, pure and simple, i.e., matching a quality paper with a quality ink set. Essentially none of the RC photo media on the market today have 100 MLux hour robustness, or even 50 Mlux hours for that matter, but some show twice as much discoloration or even more at a given exposure dose than others, e.g., various Epson versus Canon OEM brands. What more can I say?
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Educating me about OBAs is tough enough, the rest of the world might be more of a challenge. Red River's one pager on OBAs (first attachment) is a masterpiece of issue minimization. They do provide alternatives if one is really committed (second attachment). They have two rc papers represented as having low OBA content, I was able to get a sheet of the Palo Duro Satin and measure. It squeaks by per Mark A.'s definition of low OBA content:
M0 l*a*b* = 95.8, -0.2, -3.0
M2 l*a*b* = 95.2, -0.7, -0.7 (delta b* = 2.3)
My black light shows Palo Duro Satin to be slightly more florescent than Ilford Gold Fibre Silk. Given its parameters I assume it's a reasonable candidate for a low OBA rc (read inexpensive) photo paper. I'll crank out a profile, see what I think.
Thanks again to all who have contributed, it's certainly been a fun/useful thread for me.
Richard Southworth
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The basic problem with OBA laden papers is that it will look different depending on the uV content of whatever illuminant you choose to display or show the print. Change it and the print can appear different. There are other issues as well such as metameric shift which is especially a problem for cheap LED and fluorescent lighting but one thing at a time.
Whether profiles using M2 are "true" or not depends on whether the illuminant the paper is viewed under has uV or not. If not, it IS true. The problem is determining whether the light you are viewing the print has uV, and if it only has some, which a lot of regular incandescents do, whether M2, M1, or M0 is the closest match to the level of uV from it.
There is a fairly simple say to determine this with OBA papers.
Measure the Lab value of the white patch on your colorchecker card.
Create a patch in Photoshop and it has to be in Photoshop or some other program that allows Abs. Col. printing. Fill the patch with Lab=(Colorchecker white patch). Then print the patch using each of the three M0, M1, and M2 profiles made for the paper using Absolute Colorimetric. It's easy to print these on the same sheet by positioning them differently across the paper's top and making 3 prints on the same sheet.
Now, cut the patches off so you don't see any surround and have three patches. Good idea to mark the patches with M numbers to keep track.
View these patches against the Colorchecker under the illuminant of interest (home lighting, display lighting, outdoor lighting, etc).
Then just use the Mn Profile that most closely matches.
I did this test with a glossy paper that shows a b* of -12 with M1 (D50) and checked the 3 patches printed with M0, M1, and M2 against a variety of lights including 5000K 95 CRI LEDs, Solux 4700K, GMB (Judge II Fluor 5000K (F8 I think), and industrial CWF), various household incandescents, a CFL 92 CRI 5000K I use for scene photog) and assorted 2800K room LEDs with poor CRIs (80 ish). I also checked in outside in daylight and through a North facing window.
In all non-natural light cases except the Solux, the M2 profile was the closest match. All the LED lights easily had the best match with the M2 profile. The incandescents (except the Solux) and fluorescents were between the M2 and M0 but closer to M2.
The North facing window gave the best match to M0. And daylight outside gave the best match to M1 as expected.
Another way to look at it is that the OBAs added to paper don't do a hell of a lot indoors and they do squat for LEDs which are becoming ubiquitous. The better ones exceed good fluorescents spectrally. OTOH, if you are outside or even near a window OBAs can shift your paper color well to the blue/violet and you should use M1 or M0 profiles for prints displayed where window light dominates or outside.
So M2 is my default unless there is some compelling reason to choose M1 or M0. Better yet, I avoid OBA paper as much as possible. Non OBA papers produce the same profiles under M0, M1, or M2.
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I did this test with a glossy paper that shows a b* of -12 with M1 (D50) and checked the 3 patches printed with M0, M1, and M2 against a variety of lights including 5000K 95 CRI LEDs, Solux 4700K, GMB (Judge II Fluor 5000K (F8 I think), and industrial CWF), various household incandescents, a CFL 92 CRI 5000K I use for scene photog) and assorted 2800K room LEDs with poor CRIs (80 ish). I also checked in outside in daylight and through a North facing window.
In all non-natural light cases except the Solux, the M2 profile was the closest match. All the LED lights easily had the best match with the M2 profile. The incandescents (except the Solux) and fluorescents were between the M2 and M0 but closer to M2.
The North facing window gave the best match to M0. And daylight outside gave the best match to M1 as expected.
Another way to look at it is that the OBAs added to paper don't do a hell of a lot indoors and they do squat for LEDs which are becoming ubiquitous. The better ones exceed good fluorescents spectrally. OTOH, if you are outside or even near a window OBAs can shift your paper color well to the blue/violet and you should use M1 or M0 profiles for prints displayed where window light dominates or outside.
So M2 is my default unless there is some compelling reason to choose M1 or M0. Better yet, I avoid OBA paper as much as possible. Non OBA papers produce the same profiles under M0, M1, or M2.
I believe, if I remember correctly, you said, in another thread, that other intents would not show the same differences as AbsCol. Is that correct?
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I believe, if I remember correctly, you said, in another thread, that other intents would not show the same differences as AbsCol. Is that correct?
That is correct. Abs. Col. will print the specific color requested as long as it is within the printable gamut. So if you specify Lab=50,0,0, you will get a neutral gray that is almost identical to the old 18% neutral card. It will match the D4 patch on a colorchecker.
If you print it using Abs. Col. and an M1 profile it will match outside. If you print it using M2 it will match under LED illumination.
However, when you print a neutral color using Rel. or Perc. intents it scales to the media white point. So a LAB=100,0,0 will look the same indoors or outdoors using profiles made with M0, M1, or M2. It's unprinted paper.
However, once you start printing colors the M's start to matter but they don't matter nearly as much as printing Abs. Col. For instance if you print neutral colors using Rel. Col. (which I'll refer to since its behavior is specified) then the neutral colors should, while in gamut (above the black point) maintain the same xy coordinate in the CIEXY gamut. This happens with OBA papers but only if illuminated with the uV amount used in M0 or M1 and if those profiles are used to print the neutral colors.
When there is a mismatch between the Illuminant's uV and the Mn used to create the profile the tracking diverges in Rel. Col and Perc. But not a lot. In my limited testing the divergence on neutrals is no more than 2 dE with a paper that shows a 12 dE difference at the white point from M1 to M2. This difference is due to the ink/substrate absorbing uV at a fraction somewhat different than it absorbs visible light. If it was identical there would be no difference at all between M1 and M2 profiles when printing Rel. Col.
The differences are greater with some non-neutral colors. In the 3 papers I looked at the differences were only over 4 dE on a small fraction of colors. Still, the effect of M1-M2 is, of course, much reduced in comparison to Abs. Col.
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Doug,
Thank you for eloquently stating what I have been nibbling at with my posts, i.e. M2 based profiles on rc papers with OBAs are "valid" for producing prints to be viewed in a low uv environment. We all would probably go for no OBA media if always practical - I needed a reasonable cost 17"x25" paper, and the best choice was the Red River UltraPro Luster 300.
Richard Southworth
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Thanks everyone for this discussion. I've just begun making my own printer profiles and did not really understand the whole "M" thing. But now, I do!!!!
Now I just need to find the brightest, whitest, glossyish photo paper that is has very low or no OBAs... :) The paper I have now, Innova Ultra Smooth Gloss, seems to have quite a bit of OBAs and it looks quite different in each lighting situation. It really "pops" in daylight, where virtually no body will every view the prints... And, I'm quite sure that they will never be viewed in the standard D50 illuminant anywhere...
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The absolute colorimetric rendering intent reproduces the exact color that existed in the source—absolutely. If the source was light color on the dingy yellow-white of newsprint, the resulting color on your brilliant coated ink jet paper will be dingy yellow. This rendering intent is really designed for making one device simulate the appearance of another device for use in proofing. So otherwise, skip using it!
The perceptual rendering intent transforms the colors so that the image in the destination space is perceived in the same way as the original. The conversions are weighted to deal with luminance over saturation and hue because our eyes will notice differences in luminance far more than differences in saturation or hue. Luminance information provides shape and detail; this is the most important factor to perception.
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Andrew, appreciate the statements on Absolute and perceptual. Can you provide similar on RelCol?
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Andrew, appreciate the statements on Absolute and perceptual. Can you provide similar on RelCol?
RelCol is identical to Absolute with the exception of mapping of white! They share the same table.
Also, there are no rules in how a profile maker produces a perceptual rendering unlike Colorimetric (but this isn't a perfect world so you may indeed see differences). Think of Perceptual like transparency film; Agfa, Fuji, Kodak all produce different renderings based on what they believe their customers will prefer.
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Thought it might be visually useful to show the effects of M1 (full D50 w uV) and M2 (D50, uV cut) profiles printing a neutral tone curve from L=5 to L=100 with a high OBA paper.
This is Costco Glossy paper which has a large amount of OBAs. The paper white under M2 is LAB (95,-1,-2) while under M1 it is LAB(95,1,-12) for a b* shift of -10. For comparison Epson Prem. Glossy only has a b* shift of -2 which comes from the fluorescence of the substrate, not OBAs in the coating.
The 4 images are as seen under D50 without uV. The top-left image(1) is Rel. Col. using an M2 Profile. The bottom-left image(2) is also Rel. Col. but using an M1 Profile made with full D50 uV. Notice how close they are to each other in spite of the large difference in M1/2 white points from OBAs. But if looked at closely, or sampled with the eyedropper, the bottom neutral curve is slightly bluer by 1-2 dE.
Basically, using Rel. Col, (or Perceptual) there is not much difference between using a M1 or M0 profile and an M2 profile to print. This is because these intents are scaled off the media's white point so everything is adjusted to LAB(100,0,0) being mapped to that white point.
However.Abs. Col. intent is another matter entirely. If you print LAB(50,0,0) then you should measure LAB(50,0,0) within system tolerances. If the color can't be printed, as is the case when you ask to print LAB(100,0,0), it will print the closest color and it will do so based on being illuminated with D50 (uv cut - M2) or (full uV D50 - M1). Since the uV increases the spectral response at the bluer wavelengths, attempting to print LAB(100,0,0) will lay down significant yellow ink to bring the b* towards 0 and counteract the uV induced blues.
The top-right image(3) is how the image would print using the M2 profile. The printed tone curve is neutral until the gamut edge is reached (L*=95). This is because the profile was made with M2 (uV cut D50). It's slightly warmer than the images on the left because it is a completely neutral gray while the Rel. Col. images scale from media white which is very slightly bluish for the Costco glossy under uV cut D50.
The bottom-right image, made with a M1 profile, requires much more yellow ink to bring b* from -12 to 0 because this printed image is designed to be viewed in a fully compliant D50 booth or outdoors, under daylight, with high levels of uV. The result is that it looks pretty awful with no uV. But it would look fine outside. It also measures neutral using an M1 spectrophotometer.
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Doug, you have provide a series of great info, along with support bits from Andrew.
You might want to pull it all together and see if Kevin would publish. I am sure it would be valuable to many.
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However.Abs. Col. intent is another matter entirely. If you print LAB(50,0,0) ...
Hold on. Why would anyone use Absolute Colorimetric for a print? I know why I'd use it; for cross rendering. Making one print match another printed process. Make an Epson match a press sheet or contract proof. That's why the table option was created. So you'd be hard pressed to use two very dissimilar papers with or without OBAs. If you examine Proofing papers (like Epson's), very low if any OBAs, not very white and designed for matching another print process. So I don't see why anyone short of cross rendering would use Absolute rather than Relative Colorimetric. Now if your goal is an output specific paper profile based on the viewing conditions, you would (should) measure the illuminant, save a CxF file and load that into the products that correctly allow for this to be used instead of D50 which is an assumption. We've had this capability since ProfileMaker Pro days and it works quite well.
Assuming the above is correct, isn't bringing Absolute Colorimetric into the discussion of OBAs a bit like talking of how many ICC Profiles can dance on a pin? When or why would a Costco customer consider using this RI?
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http://dba.med.sc.edu/price/irf/Adobe_tg/manage/renderintent.html (http://dba.med.sc.edu/price/irf/Adobe_tg/manage/renderintent.html)
Absolute Colorimetric
Colors match exactly with no adjustment made for white point or black point that would alter the image's brightness. Absolute colorimetric is valuable for rendering "signature colors", those colors that are highly identified with a commercial product such as the yellow used by the Eastman Kodak Company, or the red used by the Coca-Cola Company.
Interesting that Lightroom has no such option for any output.
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http://dba.med.sc.edu/price/irf/Adobe_tg/manage/renderintent.html (http://dba.med.sc.edu/price/irf/Adobe_tg/manage/renderintent.html)
Absolute Colorimetric
Colors match exactly with no adjustment made for white point or black point that would alter the image's brightness. Absolute colorimetric is valuable for rendering "signature colors", those colors that are highly identified with a commercial product such as the yellow used by the Eastman Kodak Company, or the red used by the Coca-Cola Company.
Good old Abs. Useful when I was matching paint colors on some outside doors that were being replaced. Rarely, arguably never, useful for normal photographic printing. One of the few places it comes in handy, aside from pre-press hard proofing which you noted, is repro work but that is hardly a normal activity.
Interesting that Lightroom has no such option for any output.
And not surprising given what Lightroom is used for. Might as well leave it out. OTOH, Lightroom bakes in BPC when selecting Rel. Col. and that causes an unnecessary lightening of the entire image even if the image doesn't have blacks below the media's black point. They really should have an option for that since a significant fraction of photographic images don't have the deep blacks that benefit from BPC and they shouldn't have to suffer to use Rel. Col.
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Hold on. Why would anyone use Absolute Colorimetric for a print? I know why I'd use it; for cross rendering. Making one print match another printed process. Make an Epson match a press sheet or contract proof. That's why the table option was created. So you'd be hard pressed to use two very dissimilar papers with or without OBAs. If you examine Proofing papers (like Epson's), very low if any OBAs, not very white and designed for matching another print process. So I don't see why anyone short of cross rendering would use Absolute rather than Relative Colorimetric.
I pretty much agree Andrew, though there are a few applications beyond cross-rendering, where Abs. Col. is useful. For instance matching colors when doing remodeling :) More seriously, Repro work where you are trying to make as precise a match as possible to an original print or artwork, including fading and yellowing that may have occurred for older pieces. But generally, yes, there is rarely a need for Abs. Col. People that have to ask whether they should use Abs. Col. or not probably shouldn't. If you need to use it, and understand what it does, then it's there. At least in some apps like Photoshop.
Now if your goal is an output specific paper profile based on the viewing conditions, you would (should) measure the illuminant, save a CxF file and load that into the products that correctly allow for this to be used instead of D50 which is an assumption. We've had this capability since ProfileMaker Pro days and it works quite well.
Yes, quite a nice feature. One can even make prints that look good under industrial fluorescent light. And useful for all Intents.
Assuming the above is correct, isn't bringing Absolute Colorimetric into the discussion of OBAs a bit like talking of how many ICC Profiles can dance on a pin? When or why would a Costco customer consider using this RI?
I think it's useful in the sense that what I've been pointing out is just how small the difference is when printing images in Rel. Col, Perc., or Sat. intents between M0, M1, and M2 profiles. You get only the smallest differences and they are very hard to see in prints. Even those with huge amounts of OBAs.
But boy do OBAs show up using Abs. Col. That's a lot of the reason for the recent standardization using full D50 with uV for hard proof viewing booths and combining that with M1 profiles. But that's also the special case where Abs. Col. is used so syncing up M1 with full uV D50 addressed the OBA issue. Not that many still don't bother.
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But boy do OBAs show up using Abs. Col.
They do, indicating:
If you need such an RI for what it is useful for in rare cases, don't mess with OBAs. ;)
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They do, indicating:
If you need such an RI for what it is useful for in rare cases, don't mess with OBAs. ;)
I agree that avoiding OBAs is highly desirable but for possibly different reasons.
First, it is not because prints using "normal" intents with different M profiles look different. They rarely do. At most the differences are very subtle and far less than the differences between, say, Perceptual and Relative.
However, I'm concerned that OBAs will yellow quicker than paper without them but I'm no expert in that area and defer to Mark A.
OBAs also screw up view proofing because Abs. Col. is used behind the scenes on all Intents when selecting "show paper color." Getting correct view proofing when selecting that requires that your viewing setup have the correct amount of uV matching the M used and that's difficult w/o spending serious $. Avoiding OBAs gets rid of that problem and view proof works fine. A workaround, which I try to avoid, is not selecting show paper color and using a specific setup for each paper so the hard print viewing whites match the soft proof for each paper. That's relatively easy to do with things like ColorNavigator but becomes unnecessary if you aren't dealing with OBAs.