Luminous Landscape Forum
Raw & Post Processing, Printing => Colour Management => Topic started by: JRSmit on November 18, 2014, 08:28:26 am
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I am redoing the profiling of the papers i provide to customers since i have added another printer.
When profiling papers with larger OBA contect, i used the OBC function of I1Profiler-1.5.6 icm with a i1 Pro2 spectrophotometer.
I got strongly variing results, which made no sense, giving rise to a lot of frustration,
So i did a simple test: measure a chart, create the OBC chart, select a value in each of the four columns and then proceed to create a profile, with M0 as condition.
Then in the profile creation screen changed the name of the profile to create and pressed the create profile button again, in total i did this 6 times in succession with the same opened data, with no changes to the data or obc settings.
Then viewed the profiles in a profile viewer (DocBees profile manager) with the on-sight media selector tif as data to plot on the profile. Profile gamut is shown in absolute colorimetric setting.
The BAD thing: each profile created is different! (Added screenshots: first 3 are from a series of 6 created in succession, the last one is with condition m1 and the second created in succession with condition set to m1)
Differences in tone curve are significant (mainly the b dimension), also the white point "height" in L* dimension variies per created profile.
I repeated this, also saved the measurement and the workflow as well before creation of the OBC chart, so i can open it to get back at that point in the workflow.
So i opened the saved workflow, i created the OBC chart etc, and profile created is different again!
When i choose a different condition (M1 or M0) i get also very distorted profiles, especially the tone curve, also with some sort of ondulation now in the top part of the profile gamut envelope.
After stopping and starting iProfiler, i open the saved workflow and now the patch sizes are defaulted, so not the sizes used and saved as such. Also it defaults to an Isis (i have no Isis), whereas it was saved with i1 Pro selected. This did not resolve the problem.
Also it does not ask for selection of the condition (M0, M1) during the first profile creation, it just creates the profile. When i create another profile in succession it then asks to select a condition.
Conclusion: The OBC functionality in iProfiler is very badly implemented by X-Rite, how this has got past their testing and quality control is beyond my comprehension (test took about 15 minutes), assuming they do test and control quality.
And i cannot reproduce the OBC correction like i have in the profiles for my other printer,
nor can i reproduce anyhow with consistent quality.
Has anyone experienced the same problems?
If so, how did you resolve or by-passed the problem?
What is a good alterative to the OBC solution of X-Rite?
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Conclusion: The OBC functionality in iProfiler is very badly implemented by X-Rite, how this has got past their testing and quality control is beyond my comprehension (test took about 15 minutes), assuming they do test and control quality.
In my experience, over the least X number of years, they do not (test Q&E).
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In my experience, over the least X number of years, they do not (test Q&E).
Even worse than i imagined, hmmmm!
Andrew can you indicate an alternative for the OBC function? In other words get somehow a compensation for the oba effect on the measurements?
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As I recall, Argyll has some mechanism for OBA compensation.
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As I recall, Argyll has some mechanism for OBA compensation.
Sure does: http://www.argyllcms.com/doc/FWA.html
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I believe that Basiccolor Print also can compensate for OBA. Perhaps we can get Karl Koch and Graeme Gill to add a comment or two to this thread. I know that basICColor Print Production Server has been certified by Fogra to do proofs for printing on papers with a high OBA content.
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I was almost surprised at the 1200 Euros cost of that. Their non-basic class of products do tend to be quite expensive but it's limited market I suppose.
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Perhaps we can get Karl Koch and Graeme Gill to add a comment or two to this thread.
I'm not sure there is much to add to Alan's reference, unless you have a specific question.
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I got an answer from Karl of Basiccolor, who isn't a member of LuLa. So he said that I could post his answer here, if I wanted. And I do, I think it is interesting.
So that follows is Karl Koch's word, not mine:
OBA „compensation“ is something that is sooo old school since ISO 12647-2 (offset printing) and ISO 3664 (lighting) have been revised in 2009 and have been implemented in real life over the last 2 years or so.
Since then, viewing light should contain as much UV as defined in the D50 standard. This UV content excites the OBAs and makes OBA-rich paper look bluish compared with the old „D50“ lighting. Thus the bluish look should be reflected in profiles as well and OBA-compensation is counterproductive.
You are right, we also offered (and still do) OBA compensation in basICColor print and even more elaborately in basICColor IMProve. But those who want to use it should know what they are doing and what to expect. Once OBAs have been excited it is very hard to tell which „part of blue“ is due to OBAs and which one is due to a blue tint in the paper, unless you measure M1 (with UV in the measure illuminant) AND M2 (without UV in the measure illuminant) at the same time.
The OBC functionality in i1 Profiler was made for the old instrument generation that gave you M0 (with an undefined UV portion in the measure illuminant) only. Both, OBC and the brightener correction in basICColor print are guesstimates (at best) or rather guesswork (to be realistic). [/Karl Koch]
I think that this really proves that there are not an answer to how we should handle OBA-rich papers. And it is also a question if it's a profile that we do for fine art printing or for hard proofing.
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To use OBC you need to work with i1Pro2's dual scan measurement, where you make a scan with tungsten and then UV emitter, so there's some sort of information to tell the difference between OBA and bluishness of the paper.
If I understand it correctly, the purpose of OBA is to get better neutrality in certain situation - we're not ISO-obsessed german printing industry, we don't necessarily use D50-like light bulbs, not to mention the glass we use to frame our prints etc.
Furthermore, we mainly use pigment inks that are quite opaque, so I suppose they can also be considered as UV filter. And if I'm right, the more ink we put on paper, the more OBA emitted blue light it cuts, so bright neutral values may look cooler than darker ones - OBC could potentially compensate such behaviour.
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There’s also ColorAnt!
http://www.colorlogic.de/help/?p=421&lang=en
In the end, there has to be some visual tweaking as the intended light source can’t always be controlled. X-rite’s solution is visually based and could be considered anything from profile editing to a kludge of a tweak but in the end, it’s useful to have tools to adjust the profile in some areas. We really need a decent profile editor that only affects certain attributes with control over all the profile tables in the process.
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Czornyj: I worked with dual scan, else you cannot choose between m0, m1 or m2.
I am looking for a tweaking to get for the lighting conditions of my clients (definitely not D50 or similar) a decent looking print. As the OBC allows you to play with the four values, or even use a visual comparison to determine the 4 values, one can tweak the profile so the prints are ok under given lighting condition.
Whether it is old school or not up to given standard, is not the issue here. The issue is that the iProfiler software is ridiculously erratic, thus making it impossible in achieving a desired tweak in an efficient way, which is the whole idea behind this OBC function in iProfiler. :(
N.B.: A workaround sofar found is to litterally close the software and restart it after creation of 1 profile. In one instance a reboot was necessary to make it work for just 1 profile creation.
I have looked at Basiccolor and Colorlogic, but both carry a hefty price-tag, which is a showstopper for me. This is not saying that the pricetag by itself is wrong, it is just way too much for me to justify.
P.S.: I added some screenshots to the initial post, sorry for not doing that last night.
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To use OBC you need to work with i1Pro2's dual scan measurement, where you make a scan with tungsten and then UV emitter, so there's some sort of information to tell the difference between OBA and bluishness of the paper.
It certainly improves accuracy of handling FWA/OBA if you have an instrument with a switchable UV sources such as the i1 pro 2 or the Spectrolino, but it isn't necessary to have such an instrument. A normal non-UV cut (ie. UV included) i1 pro or DTP20 etc. is also quite suitable, if you use the right software.
If I understand it correctly, the purpose of OBA is to get better neutrality in certain situation - we're not
The purpose of FWA/OBA is to be able to make good looking paper cheaply.
Furthermore, we mainly use pigment inks that are quite opaque, so I suppose they can also be considered as UV filter.
No ink is opaque when it is at a low tint, and you can't print images unless this is so in places. And all inks other than black and yellow are deliberately transparent to short wavelengths of light - that's what gives them the right color!
And if I'm right, the more ink we put on paper, the more OBA emitted blue light it cuts, so bright neutral values may look cooler than darker ones - OBC could potentially compensate such behaviour.
It changes the hue of the resulting color - there is a "squaring" effect - as an ink allows more UV to hit the paper, it simultaneously allows more of the blue emitted, so it is not linear. Normal, non FWA/OBA papers are better behaved due to this.
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In the end, there has to be some visual tweaking as the intended light source can’t always be controlled.
You don't have to visually tweak - Argyll's illumread provides a means of avoiding that.
See http://www.argyllcms.com/doc/illumread.html and http://ist.publisher.ingentaconnect.com/content/ist/cic/2011/00002011/00000001/art00013
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You don't have to visually tweak - Argyll's illumread provides a means of avoiding that.
But it’s oh so much easier to get the results you desire (assuming the software really does provide WYSIWYG).
IF I could get a dollar for every time a value is supposed to represent a desired match but didn’t, I’d have retired by now.
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But it’s oh so much easier to get the results you desire (assuming the software really does provide WYSIWYG).
That works if you have access to the illuminant at the time you are printing test charts and making the profile, if your color vision is the same as your clients, and if you are on top of your game when you make the judgement.
A measurement based approach can be used separately from making the profile, and is not subject to the foibles of a particular observer.
Either can work.
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That works if you have access to the illuminant at the time you are printing test charts and making the profile, if your color vision is the same as your clients, and if you are on top of your game when you make the judgement.
You or someone will have to at some point no? How on earth would you know if the compensation worked or not if you didn’t?
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Czornyj: I worked with dual scan, else you cannot choose between m0, m1 or m2.
I am looking for a tweaking to get for the lighting conditions of my clients (definitely not D50 or similar) a decent looking print. As the OBC allows you to play with the four values, or even use a visual comparison to determine the 4 values, one can tweak the profile so the prints are ok under given lighting condition.
Whether it is old school or not up to given standard, is not the issue here. The issue is that the iProfiler software is ridiculously erratic, thus making it impossible in achieving a desired tweak in an efficient way, which is the whole idea behind this OBC function in iProfiler. :(
N.B.: A workaround sofar found is to litterally close the software and restart it after creation of 1 profile. In one instance a reboot was necessary to make it work for just 1 profile creation.
I have looked at Basiccolor and Colorlogic, but both carry a hefty price-tag, which is a showstopper for me. This is not saying that the pricetag by itself is wrong, it is just way too much for me to justify.
P.S.: I added some screenshots to the initial post, sorry for not doing that last night.
I had to hunt down what these M0, M1,...etc. measurements were about with regard to getting a "decent print" with OBA papers and found this...
http://www.konicaminolta.eu/en/measuring-instruments/learning-centre/colour-measurement/colour/iso13655-demystified.html
Scroll down to the OBA effects of a collection of papers viewed under different lights.
So from that what I'm to understand in this discussion is that there needs to be a way to create tweaks during the measuring and creation of a paper profile to correct for the constantly changing color of paper white with various levels of OBA's revealed under different illuminants (as shown in that Minolta link image) and the way to do that is to get the profile to make the rest of the non-paper printed color tones match the bluish look of that paper?
I'm assuming this process of OBA compensation also allows targeting the measurement and tweaks within the profile for a specific illuminant/paper OBA behavior.
To ask it simply is this a question of generating a paper profile to put more yellow in the print or less yellow to get the overall look of the print to match a bluish white paper viewed under a light that will make the paper appear bluish?
Who views prints in daylight? Most prints are viewed under lights that don't reach that far into the UV spectrum and if they do you'll be dealing with the EPA and your eye doctor.
BTW define a "decent print" with regard to OBA issues.
Here's a shot I took of one of my Epson prints viewed under two different lights and posted at Photo.net a while back of I'm assuming OBA paper that was printed using "Printer Manages Color". The question I have is which version of the print could do for some OBA compensation and how would it be seen in an ICC printer profile? What would be the results that would deliver a better "decent print"?
http://static.photo.net/attachments/bboard/00W/00WpI5-258209584.jpg
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So that follows is Karl Koch's word, not mine:
OBA „compensation“ is something that is sooo old school since ISO 12647-2 (offset printing) and ISO 3664 (lighting) have been revised in 2009 and have been implemented in real life over the last 2 years or so.
Since then, viewing light should contain as much UV as defined in the D50 standard. This UV content excites the OBAs and makes OBA-rich paper look bluish compared with the old „D50“ lighting. Thus the bluish look should be reflected in profiles as well and OBA-compensation is counterproductive.
I would really appreciate it if someone would explain why one would want to use OBA compensation as I find the whole subject very confusing.
It seems to me that its purpose, for normal printing rather than proofing, should be to adjust the profile so that the effect of more or less UV in the target illuminant (compared to the standard UV content of D50) is minimized. This would mean that the color shifts due to more or less UV in the target illuminant would be reduced by the profile (so that the print would more nearly match a D50 proof, when chromatic adaptation is taken into account).
Or, as an example, if:
- we do a test print using a profile without OBA compensation for illuminant D50 and view it under illuminant D50
- and we do a test print using a profile with OBA compensation for illuminant D50* (where D50* has a higher UV content than D50, but is the same as D50 in all other respects) and view it under D50*
- then the prints should ideally look the same when viewed side by side (each illuminated by its target illuminant).
The same would apply to an illuminant other than D50*, but we would then be relying on chromatic adaptation (so we could not view the prints side by side).
If we know that the target illuminant has the same UV content as D50 then OBA compensation would be pointless.
If we do not know what the target illuminant is going to be then OBA compensation is also pointless (not possible?).
Is this correct? Most likely not! :)
Robert
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I would really appreciate it if someone would explain why one would want to use OBA compensation as I find the whole subject very confusing.
In simple terms, the introduction of OBA’s may produce color issues when one measures the paper to build a printer profile. Does the instrument record this UV or does the instrument filter (cut/exclude) the UV? The discontinued GretagMacbeth Spectrolino had provisions to measure with, or without a UV filter that could be attached to the measurement head. The X-Rite iSis has the ability to measure UV or remove that component from the measured data thanks to the use of a dual illuminant inside the unit. Both devices are expensive. For those in the market for an affordable Spectrophotometer the choice was limited to either a UV Cut or Non-Cut product if there was even an option.
http://www.luminous-landscape.com/reviews/accessories/eye_one_pro_ii.shtml
It's even easier to understand than color gamut!
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In simple terms, the introduction of OBA’s may produce color issues when one measures the paper to build a printer profile. Does the instrument record this UV or does the instrument filter (cut/exclude) the UV? The discontinued GretagMacbeth Spectrolino had provisions to measure with, or without a UV filter that could be attached to the measurement head. The X-Rite iSis has the ability to measure UV or remove that component from the measured data thanks to the use of a dual illuminant inside the unit. Both devices are expensive. For those in the market for an affordable Spectrophotometer the choice was limited to either a UV Cut or Non-Cut product if there was even an option.
http://www.luminous-landscape.com/reviews/accessories/eye_one_pro_ii.shtml
It's even easier to understand than color gamut!
I don't find it easy to understand Andrew. I have an i1Pro2 so I can do OBA compensation using i1Profiler (or more quickly using Argyll as it doesn't require a dual-pass scan), but it's not clear to me if I should use OBA compensation and for what conditions.
That's why I tried to give a scenario in my post above. Do you agree with what I've said, or do you think I've got it wrong? If I have it wrong then I really would appreciate it if you would set me straight.
Robert
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You or someone will have to at some point no? How on earth would you know if the compensation worked or not if you didn’t?
Sure, but you don't have to actually be there when you make the profile - someone can measure and send the data, and evaluate the result, independently of where or who makes the profile.
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I don't find it easy to understand Andrew. I have an i1Pro2 so I can do OBA compensation using i1Profiler (or more quickly using Argyll as it doesn't require a dual-pass scan), but it's not clear to me if I should use OBA compensation and for what conditions.
First things first; depends on the conditions. The paper, the illuminates, the software and hardware used to build a profile. You might need the compensation, you might not. Place the print in the condition and look at it.
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So from that what I'm to understand in this discussion is that there needs to be a way to create tweaks during the measuring and creation of a paper profile to correct for the constantly changing color of paper white with various levels of OBA's revealed under different illuminants (as shown in that Minolta link image) and the way to do that is to get the profile to make the rest of the non-paper printed color tones match the bluish look of that paper?
Calling it "tweaks" is one way of putting it - but that's describing a mechanism, not what you are trying to achieve.
What you are trying to achieve is far simpler :- to make the measurements reflect the color appearance under the intended viewing conditions. What needs to be adjusted for is the difference between the illuminant the instrument is using and the viewing illuminant.
I'm assuming this process of OBA compensation also allows targeting the measurement and tweaks within the profile for a specific illuminant/paper OBA behavior.
That's the only way it can work.
To ask it simply is this a question of generating a paper profile to put more yellow in the print or less yellow to get the overall look of the print to match a bluish white paper viewed under a light that will make the paper appear bluish?
The aim is to make the measurements reflect the appearance under the viewing illuminant, so that the color profile can do its job.
Who views prints in daylight?
People with windows ?
It is considered normal enough that graphic arts has adopted as the standard - D50!
Most prints are viewed under lights that don't reach that far into the UV spectrum and if they do you'll be dealing with the EPA and your eye doctor.
A lot of people use incandescent or fluorescent lighting - and it triggers the FWA/OBA's. In the future you may be right - LED lighting is very UV poor, but the fact is that paper makers wouldn't add FWA/OBA's to paper if no-one could see it.
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Who views prints in daylight?
People with windows ?
It is considered normal enough that graphic arts has adopted as the standard - D50!
Window light includes the blue canopy skylight contaminator that is not part of D50 spectral emission and the only artificial light that is considered closest to D50 is the 4700K Solux halogen which looks very much like a sunbeam coming through my window.
IOW window light is TOO BLUE and is not an ideal light source to base a color rendering standard. I should know I used to make fine art acrylic paintings on canvas having to use window light to work under and it sucks for showing true color rendering. Once the sun beam shown through my window at the right time of day the colors looked correct.
There's two components of white natural light that makes this very confusing to wrap one's head around and that is the actual color of white D50 light AND what the actual spectral reflectance qualities it exhibits on real objects for instance when I've seen a sunbeam make my acrylic yellows and oranges increase in saturation and luminance on canvas and bluish diffused window light make the yellow and orange shift to cyan and become less saturated and luminous. Which one of those light's components (their color? or spectral reflectance?) created that appearance?
But Andrews point made it more clear for me on what this topic is about...
In simple terms, the introduction of OBA’s may produce color issues when one measures the paper to build a printer profile. Does the instrument record this UV or does the instrument filter (cut/exclude) the UV? The discontinued GretagMacbeth Spectrolino had provisions to measure with, or without a UV filter that could be attached to the measurement head. The X-Rite iSis has the ability to measure UV or remove that component from the measured data thanks to the use of a dual illuminant inside the unit.
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Window light includes the blue canopy skylight contaminator that is not part of D50 spectral emission and the only artificial light that is considered closest to D50 is the 4700K Solux halogen which looks very much like a sunbeam coming through my window.
Daylight is very variable, but I've certainly measured daylight that is pretty similar to D50 during a large number hours around mid-day. But this is off topic - the topic at hand is UV content of illuminants, not their white point or other spectral composition. The nature of a reflective medium is that it's white point automatically changes with the illuminant (times it's reflectance spectrum, which is constant and ideally is close to flat). What doesn't track is a change in relative UV content when the medium has FWA/OBA.
There's two components of white natural light that makes this very confusing to wrap one's head around and that is the actual color of white D50 light AND what the actual spectral reflectance qualities it exhibits on real objects for instance when I've seen a sunbeam make my acrylic yellows and oranges increase in saturation and luminance on canvas and bluish diffused window light make the yellow and orange shift to cyan and become less saturated and luminous. Which one of those light's components (their color? or spectral reflectance?) created that appearance?
The spectrum causes the color. The light you see is the illuminant spectrum times the pigment reflectance spectrum then integrated into the 3 color signals in your eyes. You may well be observing viewing condition effects as well, if there is a drastic change in illumination.
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Daylight is very variable, but I've certainly measured daylight that is pretty similar to D50 during a large number hours around mid-day. But this is off topic - the topic at hand is UV content of illuminants, not their white point or other spectral composition. The nature of a reflective medium is that it's white point automatically changes with the illuminant (times it's reflectance spectrum, which is constant and ideally is close to flat). What doesn't track is a change in relative UV content when the medium has FWA/OBA.The spectrum causes the color. The light you see is the illuminant spectrum times the pigment reflectance spectrum then integrated into the 3 color signals in your eyes. You may well be observing viewing condition effects as well, if there is a drastic change in illumination.
How far into the UV part do you have to measure to be sure to get all the UV light that affects OBA? I sometimes do a special profile for an important exhibition, where I take my time to go the exhibition area to actually measure the light that will be used. I use an ordinary i1Pro2 to measure the light, but I don't know if it can measure all the important parts of the UV spectrum. And if I then use that measurement in i1Profiler and then do a dual scan, does that give me a profile that's corrected for the UV light?
Best
Stefan
www.profiler.nu
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First things first; depends on the conditions. The paper, the illuminates, the software and hardware used to build a profile. You might need the compensation, you might not. Place the print in the condition and look at it.
Yes, I do agree that the acid test is to view the print without OBA compensation under the target illuminant - then if it doesn't look right try it with OBA compensation. The problem with that, though, is that one print might look fine whereas another might not. For an exhibition or gallery it wouldn't be feasible to check each print then reprint the ones that don't look right, and mostly we cannot check the print in a customer's house or office.
It would seem to me that it would be sensible to use OBA compensation where we can measure the target illuminant (as, for example, in a gallery). Equally, if our customer can tell us that they are using D65 fluorescent lighting, say, then, again, using OBA compensation would more that likely improve the print.
So, to generalise, I think that OBA compensation should be used where we know, or can measure, the target illuminant (which is required for OBA compensation anyway).
Of course, the best thing is to use papers that don't have OBAs! (which is my approach :)).
Robert
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...........Of course, the best thing is to use papers that don't have OBAs! (which is my approach :)).
Robert
Uhuh, seems like safe advice, but is this a binary matter? Does it make a difference to how you would approach profiling whether the paper has a "little bit" of OBA versus "a lot", or whether the OBA is embedded in the base or in the coating, and exactly what chemical compound it is made of? Maybe there are papers for which the OBA component just isn't worth fussing over, while for others the fuss may indeed be worthwhile?
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Uhuh, seems like safe advice, but is this a binary matter? Does it make a difference to how you would approach profiling whether the paper has a "little bit" of OBA versus "a lot", or whether the OBA is embedded in the base or in the coating, and exactly what chemical compound it is made of? Maybe there are papers for which the OBA component just isn't worth fussing over, while for others the fuss may indeed be worthwhile?
I agree with Mark. More important than the amount of UV, is the response of the particular OBA(s) used.
Besides, most silicon based sensors are not all that sensitive to UV wavelengths, so it could only approximate the effect on OBAs that are stimulated by 350-400 nm UV. Is that also the UV wavelength range that these OBAs are stimulated (excited) by, and which longer OBA wavelengths are then emitted as fluorescence?
Cheers,
Bart
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I agree with Mark. More important than the amount of UV, is the response of the particular OBA(s) used.
Besides, most silicon based sensors are not all that sensitive to UV wavelengths, so it could only approximate the effect on OBAs that are stimulated by 350-400 nm UV. Is that also the UV wavelength range that these OBAs are stimulated (excited) by, and which longer OBA wavelengths are then emitted as fluorescence?
Cheers,
Bart
Yes, I agree with Mark too.
The problem, as I see it, is that the OBA causes light to be reflected at a different wavelength: so white becomes blue-ish. That's fine for making the paper look white, but when we then put ink down over the paper, what happens? For example, does yellow get a green tint (because the underlying white paper reflects a blue-ish light)? If it does, and the instrument is not UV-cut, then presumably the profile will compensate for this automatically ... without any need for OBA-compensation.
So what is the need for OBA-compensation then? Presumably, what it will do is to try to make the paper white more yellow ... and in so doing defeat the purpose of putting OBA into the paper in the first place.
With this kind of thinking, it would seem that OBA compensation is really only useful for proofing, so that we can view both the proof and the target side-by-side without the proof looking much whiter than the target (or vice-versa).
I seem to be swinging from one side to the other at this stage :). To OBA-compensate or not to OBA-compensate, that is the question.
Robert
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So what is the need for OBA-compensation then?
The simple answer to all this is avoid papers with lots of OBAs! There is no prefect solution and depending on where the prints are viewed, the print may look acceptable or not (one would expect the eye to adapt too).
The basic question is, do you measure with UV or make it go away via filters then, do you compensate for a specific ambient condition? We have tools to measure the light under which a print is examined and use that inside the profile. We have tools (tweaks) for the OBAs. If you can target the profile for where and how the print is viewed, great. If not, all bets are off (if the prints are to be moved about).
What we need is a simple to use and effective profile editor. Something like Kodak's Custom Color ICC which worked inside Photoshop. Something that works like an image editor, not a profile editor (ProfileMaker Pro's module comes to mind as one that seems designed to confuse the end user).
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Indeed the oba effect varies with the lightsource, i used differents sources, ordinary halogen, led, solux4700, direct sunlight, daylight in a cloudy day, daylight bluesky, behind a window etc. The visual match with the control card simply gives different results (different values for each of the four wegdes).
So what i do is in OBC to set values , create a profile in m1 condition, evaluate its tone curve in absolute colorimetric setting using docbees profilemanager . Based on my experience i get with this approach the tone curve in ballpark kind of shape in rather quick steps. Then print and visually evaluate the print or prints in the typical lighting situations in house and fine-tune if needed.
Actually, if the amount of oba is not large, creating a profile in m0 condition may be enough.
Anyhow it is a subjectively determined acceptable "point" in a very broad spectrum, so it is just that, nothing more.
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The simple answer to all this is avoid papers with lots of OBAs!
Yes, totally. Canson Baryta is a nice example, with little OBAs; Canson Platine even nicer IMO (with no OBAs).
What we need is a simple to use and effective profile editor. Something like Kodak's Custom Color ICC which worked inside Photoshop. Something that works like an image editor, not a profile editor (ProfileMaker Pro's module comes to mind as one that seems designed to confuse the end user).
How would you use the profile editor? With something like the XRite control card? Tweak so that the colors match? I would expect that this sort of approach could lead to some disastrous effects!
Robert
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How would you use the profile editor?
http://www.kodak.com/TW/en/professional/products/software/colorFlow/customColor/customColor.shtml
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http://www.kodak.com/TW/en/professional/products/software/colorFlow/customColor/customColor.shtml
Not exactly clear from the link what the workflow would be. Have you used this tool? Does it do what you want? How much does it cost?
Robert
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Not exactly clear from the link what the workflow would be. Have you used this tool? Does it do what you want? How much does it cost?
Used it for years (since day 1), no longer available. If you know how to edit an image in Photoshop, you know how to edit a profile in Custom Color. Best editor ever, I have a very old Mac setup to run it.
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How far into the UV part do you have to measure to be sure to get all the UV light that affects OBA?
It depends on the particular type of FWA, but typically the peak sensitivity is around 350 nm, and it drops to zero beyond 300nm.
I sometimes do a special profile for an important exhibition, where I take my time to go the exhibition area to actually measure the light that will be used. I use an ordinary i1Pro2 to measure the light, but I don't know if it can measure all the important parts of the UV spectrum.
It can't. It usually stops at 380 nm. You would need a more specialized instrument such as a JETI 1211 UV which goes down to 250nm, or a similarly configured module from Ocean Optics or StellarNet. The normal JETI 1211 goes down to 350nm. But note that ArgyllCMS illumread avoids the need for such instruments, and in fact gives a better result if you make use of the paper you intend to print on.
And if I then use that measurement in i1Profiler and then do a dual scan, does that give me a profile that's corrected for the UV light?
I'm not an i1Profiler expert, but I get the impression that it relies on printing out a series of samples that assume different levels of UV exitation, and then you visually match one of the samples to a reference under the illuminant. This also avoids the need to use a special instrument to measure the illuminant UV levels.
In fact you don't want to measure the UV levels, because you would then have to estimate or measure the FWA spectral excitation curve.
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If it does, and the instrument is not UV-cut, then presumably the profile will compensate for this automatically ... without any need for OBA-compensation.
Well no - that's the point of FWA compensation, it compensates for the fact that the instrument illuminant relative UV level is different from that of the viewing illuminant. If they are the same (i.e. both incandescent), then yes, FWA compensation isn't needed.
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I would really appreciate it if someone would explain why one would want to use OBA compensation as I find the whole subject very confusing.
Robert
The measurement instrument, I use I1 Pro2, measures the OBA effect and shows the results, f.i. a grey wedge, with a blue bias depending the amount of OBA. But if one observes the same grey wedge it does not appear so blue as the measurements indicate. This however varies with the sort of lighting/illuminant used.
According to the ISO3664:2009 standard , if you use a illuminant in a light booth that complies with the standard regarding UV light, using the M1 condition during profile creation should result in a correlation between measured and observed wrt the OBA effects.
The M0 condition does also measure OBA effect but so-called undefined, in effect the OBA effect measured is less pronounced than in condition M1.
Even M2, UV-cut, only means that in the measurement the OBA effect is eliminated, but it is not eliminated for the observer.
But in a different illuminant, say a normal household halogen, or a LED light, or a fluorescence energy saving or a mixture of those with daylight without direct sunlight, or direct sunlight, or through a thick window-pane, etc, the OBA effect varies. Unlike non OBA papers, the spectral behavior of the reflection changes, that is what makes it a moving target.
So ideally if there is only one light condition used for observing, with a known behavior (f.i. compliant with ISO3664:2009 standard), one can create a matching (sort of) profile.
Great for the graphic industry, but what about the individual observer? Then just M0, M1, M2 does not work out of the box, you have to have some way of applying a compensation though trial and error to come to an acceptable result.
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Well no - that's the point of FWA compensation, it compensates for the fact that the instrument illuminant relative UV level is different from that of the viewing illuminant. If they are the same (i.e. both incandescent), then yes, FWA compensation isn't needed.
Yes, I got a little confused there :). I have a couple of follow-up questions though.
1. If the target illuminant has a higher UV content than the measuring instrument, can OBA compensation correct for the shift in colors (other than white). For example, a pale yellow will fluoresce, even if the ink does not, because of the underlying paper: does the Argyll OBA compensation correct for this? It would seem difficult to be able to estimate the extent to which the ink has blocked out the paper.
2. Would a dual-scan with/without UV not give a much more precise estimate of the fluorescence than a single estimate based on the spectral shape of reflected white?; and make it possible to fairly accurately compensate on the full gamut of colors?
i1Profiler allows for 2. above, followed by a selection (or measurement) of the target illuminant. The problem though is that the instrument can't measure UV directly, so I don't see how it would know the UV content of the (measured) target illuminant. Even if a standard illuminant is chosen (say F1), the spectrum shown only goes from 380nm.
Robert
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Yes, I got a little confused there :). I have a couple of follow-up questions though.
1. If the target illuminant has a higher UV content than the measuring instrument, can OBA compensation correct for the shift in colors (other than white). For example, a pale yellow will fluoresce, even if the ink does not, because of the underlying paper: does the Argyll OBA compensation correct for this? It would seem difficult to be able to estimate the extent to which the ink has blocked out the paper.
2. Would a dual-scan with/without UV not give a much more precise estimate of the fluorescence than a single estimate based on the spectral shape of reflected white?; and make it possible to fairly accurately compensate on the full gamut of colors?
i1Profiler allows for 2. above, followed by a selection (or measurement) of the target illuminant. The problem though is that the instrument can't measure UV directly, so I don't see how it would know the UV content of the (measured) target illuminant. Even if a standard illuminant is chosen (say F1), the spectrum shown only goes from 380nm.
Robert
Even if the UV part of the illumination is measured, how to correlate that to the reflected result of given paper?
The measurement devices as i1 Pro2 have their own illuminants
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Even if the UV part of the illumination is measured, how to correlate that to the reflected result of given paper?
The measurement devices as i1 Pro2 have their own illuminants
Well, the measurement could compare spectrum of the illuminant, measured directly, to the spectrum of the reflected white (as does Argyll). But what about the effect of different ink densities and colors on the target paper?
Also, how can the i1Pro2 measure the UV in the target illuminant? ... it can't do it directly; Argyll measures it indirectly by comparing the spectrum of the illuminant to the spectrum of the reflected white ... does i1Profiler do the same? There seems to be a lot of guesswork needed on our part (or perhaps there's documentation somewhere that explains this in full detail using English rather than CIE-speak).
Robert
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Great for the graphic industry, but what about the individual observer? Then just M0, M1, M2 does not work out of the box, you have to have some way of applying a compensation though trial and error to come to an acceptable result.
Do you say this because for an individual observer we have no way of knowing for sure what the illuminant will be, whereas in the graphic arts the illuminant will be D50? If so, what about displaying in a gallery, say, where the illuminant is known or can be measured (but may not be D50)?
Robert
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Do you say this because for an individual observer we have no way of knowing for sure what the illuminant will be, whereas in the graphic arts the illuminant will be D50? I
Well that's one assumption (there are all kinds of ways to view a print we are told are "D50").
There are at least two light sources at play here and often more. The Light source in the measuring instrument and the light source used for viewing the print with all those OBA's (how much?)
In the old days we had basically two options. One was to include the UV, the other was to filter it out. Some would say filtering out, 'ignoring' the UV's affect on the measurement data was dumb. Other's would say it only makes sense to filter it out. And neither approach deals with the 2nd light source; where the print is being viewed.
What X-rite did was provide a method of visually 'tweaking' a profile based on viewing output under the conditions where the final print will be viewed and comparing it with their targets of gray patches with numbers one inserts into the software for dog knows what compensation. Then you visually compare the two. I think, like the idea of a good profile editor (where you work visually, not numerically where sometimes we do get into trouble with visual mismatches), makes sense. This is kind of what's happening here.You have to view the X-rite supplied target and what you print from the profiles side by side, on-site where you wish to view the prints for that compensation just to enter a value into their software.
As to what is affected, pretty sure all colors are affected to some degree and differently depending on the 'compensation' and when you use the X-rite OBA target thingie, it's a group of gray patches you visually examine to decide what compensation if you will, the new profile will undergo.
In the end, it's a mess which causes more work but would all be avoided if you just cease using papers with high OBA's and control how the print is being viewed, something that isn't always possible.
I just built a customer a profile from HanaPhoto Luster 260, the paper white had a bStar of -9.13! For fun I tried running it through ColorAnt using max Brightener compensation (100) and the resulting bStar was 0.39! I can't handle any of this X-rite compensation stuff, the client is in Peru! I provided a profile both ways, he reported that the one with compensation was subtilely better (so nothing super dramatic here). But I have no idea how he's going to view the prints or where and asked him to try different lightning conditions for both profiles. Again, he preferred the one 'fixed' by running the measurement data through ColorAnt. For remote work, that's about the best I can do. And with a bStar of -9, I suggested he find another paper to use! He originally sent me 5 papers to profile and all but this one Luster paper either had no OBA's or tiny amounts.
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What X-rite did was provide a method of visually 'tweaking' a profile based on viewing output under the conditions where the final print will be viewed and comparing it with their targets of gray patches with numbers one inserts into the software for dog knows what compensation. Then you visually compare the two. I think, like the idea of a good profile editor (where you work visually, not numerically where sometimes we do get into trouble with visual mismatches), makes sense. This is kind of what's happening here.You have to view the X-rite supplied target and what you print from the profiles side by side, on-site where you wish to view the prints for that compensation just to enter a value into their software.
Do you think that the XRite visual approach is better than the dual-scan approach? I would have thought that with dual-scan the profiling software can see exactly what the fluorescent effect is on all of the colors in the target. Since the software knows the UV content in the instrument's light, and as we specify the target illuminant (or measure it), the software should then be able to extrapolate to the target illuminant fairly accurately. For standard illuminants the UV content should be known, but I do have a question about how i1Profiler estimates the UV content of the illuminant from a measurement (since the i1Pro2 cannot 'see' the UV) ... any idea where we could get an answer?
In the end, it's a mess which causes more work but would all be avoided if you just cease using papers with high OBA's and control how the print is being viewed, something that isn't always possible.
Yes, totally. The question is, how do we know how much OBA is in the paper? Canson specifies that papers like the Platine have no OBAs, but for other papers like the Baryta there is no mention of OBAs so I assume that the paper will have some (but probably not much as the whiteness will mostly come from the coating).
I just built a customer a profile from HanaPhoto Luster 260, the paper white had a bStar of -9.13!
Nice blue paper :). But a b* of -10 may just show that the paper is blue; it may contain little or no OBAs. Probably a better estimate would be to look at the tell-tale hump at the blue end of the spectrum (from reflected white). Argyll's spotread is good for that.
Robert
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In my graphic design days back in the '80's I don't remember OBAs even mentioned as a concern when I'ld receive in the mail free tastefully designed paper sample booklets off a commercial offset press showing various sheens and off white hues with beautiful images printed from manufacturers such as Potlatch and others.
Maybe it was my lack of training or exposure to high end graphics productions like corporate annual reports that didn't get me to view these papers under various lights to check how blue they'ld turn. I didn't have a Solux4700K, just window light, tungsten or soft white fluorescent tubes. Never gave much thought to light having any affect on white hues. I always thought the manufacturer was controlling that by specifically naming their papers with names like "Egg Shell", "Natural", "Bone", "Ivory", etc.
I do wonder though now why I have to apply a middle slider reduction in Levels blue channel to make the image more yellow when I use "Printer Manages Color" on Epson Ultra Premium Photo Glossy paper which I found out does have OBA's.
But then I decided to really check out all the varieties of lights around my home that I view my prints and I notice some lights only affect the white of the paper while others leave the white unchanged but produce a strange metameric effect with the ink (LED's excite the cyan ink with pigment based Epson Dura Brite Ultra ink).
Below are shots I took of the same Epson Ultra Premium Glossy paper print under various lights to try to figure out whether the color of light is causing the paper white to change or the paper's OBAs. Now my camera wouldn't record the cyan metamerism of the LED's I saw with my eyes though you might see some slight violet bias in the lower right shadow of the white rose on some. Tungsten of course gave the most flattest and uniform rendering.
So my question is how does anyone detect OBA's visually when it's quite difficult to separate the color of light from its spectral reflectance characteristics in how it excites OBA's?
And can someone post a comparison between two prints of the same image on the same OBA paper using two profiles, one print profile built with OBA compensation and the other without? Is it something similar to my Blue channel Levels slider adjustment to make the print appear more yellow on bluish looking paper?
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Tim, get yourself an LED Blacklight flashlight.
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Tim, get yourself an LED Blacklight flashlight.
Andrew, I know why you suggests this as a way to check for OBA's, but then we're right back into the circular logic having to do with why this is practical since we don't view prints under blacklight.
I really don't need to check whether a paper has OBA's. I want to know the extent of whether this is a real issue that needs to be fixed with an ICC profile. I'm seeing a huge disconnect on the visual part of seeing this as a real problem due to not being able to see this visually even on OBA paper.
I can't see how an ICC profile can fixed this moving target as well as for targeting one specific light and OBA paper. It looks like a recipe for madness.
Can someone show how this makes a better looking print?
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Tim, you can't fix a moving target, I explained this earlier. You can fix a non moving target! The flashlight or a Lab reading can help you detect if you may have an OBA issue.
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Tim, you can't fix a moving target, I explained this earlier. You can fix a non moving target! The flashlight or a Lab reading can help you detect if you may have an OBA issue.
But I just said I'm not wanting to check for whether a paper has OBA's.
I want someone to show how this is fixed with an ICC profile with an A/B demo. What does this look like?
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I want someone to show how this is fixed with an ICC profile with an A/B demo. What does this look like?
It's fixed using a number of options (OBA correction in ColorAnt, the OBA system by X-rite etc). You want me to show you? Come on down, bring your check book, I'll show you. Or you can read the manuals which should be online (ColorAnt is). Or you could just build two profiles each way and view the results from a good reference image under any number of light sources. What does the fix look like? Usually a bit better! Lack of a possible color cast. Build a profile without OBA, print a reference image, VIEW IT under the illuminant. If it's got OBAs that cause a color shift, fix it using the tools available.
This isn't a big issue Tim! I've built hundreds upon hundreds of profiles plus a group for Epson (Exhibition Fiber) so perhaps thousands of people have used those profiles without a lick of OBA compensation. The net isn't filled with Epson users complaining but none the less, the best approach is to use papers without OBA's! And OBA's have negative consequences above and beyond how they appear, they can cause issues in terms of the archival properties and qualities of the print (they change over time). They ain't good Tim!
We have a system even without OBA's that assume D50 viewing conditions and lots of folks don't view their prints that way. The fix? Like OBA, we measure the light and use that inside the profile instead of the D50 assumption. It helps but like OBA, it's fixing a moving target and the end results are usually subtle. Just as my client with the HUGE OBA paper reported when viewing two prints made from two different profiles.
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Great for the graphic industry, but what about the individual observer? Then just M0, M1, M2 does not work out of the box, you have to have some way of applying a compensation though trial and error to come to an acceptable result.
It doesn't have to be trial and error.
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1. If the target illuminant has a higher UV content than the measuring instrument, can OBA compensation correct for the shift in colors (other than white). For example, a pale yellow will fluoresce, even if the ink does not, because of the underlying paper: does the Argyll OBA compensation correct for this? It would seem difficult to be able to estimate the extent to which the ink has blocked out the paper.
Well I can't speak for how others do it, but yes, ArgyllCMS's FWA compensation is spectral, and corrects the colors of the whole profile.
2. Would a dual-scan with/without UV not give a much more precise estimate of the fluorescence than a single estimate based on the spectral shape of reflected white?; and make it possible to fairly accurately compensate on the full gamut of colors?
Yes, having an instrument that can take two measurements with more and less UV provides a better way of estimating the quantum efficiency of the fluourescent agent, as well as its emission spectrum. This has nothing to do with correcting or not correcting a full gamut of colors.
i1Profiler allows for 2. above, followed by a selection (or measurement) of the target illuminant. The problem though is that the instrument can't measure UV directly, so I don't see how it would know the UV content of the (measured) target illuminant. Even if a standard illuminant is chosen (say F1), the spectrum shown only goes from 380nm.
As I mentioned before, I'm not a ProfileMaker expert, but my understand is that they print a series of test patches that assumed different levels of UV from the illuminant, and then rely on the user making a visual match to a reference color. This is a different way of extracting similar information about the illuminant, to that obtained using ArgyllCMS's illumread.
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Do you think that the XRite visual approach is better than the dual-scan approach?
I don't think it works that way. My understanding is that X-Rite use both :- dual scan to figure
out what the FWA emission spectrum looks like as well as how that interacts with the
colorants, and the visual matching step is to estimate the UV content of the target illuminant.
Both would then be combined to spectral compensate the whole profile. (At least, that's
how I would be doing it if I were them.)
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So my question is how does anyone detect OBA's visually when it's quite difficult to separate the color of light from its spectral reflectance characteristics in how it excites OBA's?
It's pretty obvious from the spectral reflectance of the paper itself when measured using a non-UV filtered instrument like the i1pro. Non-FWA impregnated paper has a flat spectrum that gently bends down in the short wavelengths. FWA containing paper has peak in the blue that then sharply rolls off as you get to the wavelengths that are being absorbed by the FWA. See http://www.axiphos.com/BrightnessReview.pdf
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I don't think it works that way. My understanding is that X-Rite use both :- dual scan to figure
out what the FWA emission spectrum looks like as well as how that interacts with the
colorants, and the visual matching step is to estimate the UV content of the target illuminant.
Both would then be combined to spectral compensate the whole profile. (At least, that's
how I would be doing it if I were them.)
Yes, i1Profiler does use both of course, as well as measuring (or specifying) the target illuminant. There's some useful information here: Northlight i1Pro2 Review OBA-Compensation (http://www.northlight-images.co.uk/reviews/profiling/i1_pro2_photo.html#optical_brightener_compensation_profiling).
Unfortunately, checking out OBA compensation is extremely time-consuming. What we really need is a clear recommendation on when to use OBA compensation and when not to use it. Presumably someone, or some organisation, has already done the required testing - in which case it would be good to get the recommendations.
In the meantime it seems to me that the best recommendation is to use papers with no OBAs or very little.
But then what about the shading agents? How do we know if a paper has some (I suppose we could look at the spectrum) ... and if we do know, what can we do about them? What are shading agents used for? Is it an additional mechanism to make the paper look whiter? (by reducing the yellows). Could papers have little or no OBAs but have quite a lot of shading agents, and could these be just as big a problem (as they may affect a wider part of the spectrum, and as we have no mechanism to compensate them out)?
Robert
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But then what about the shading agents? How do we know if a paper has some (I suppose we could look at the spectrum) ... and if we do know, what can we do about them? What are shading agents used for? Is it an additional mechanism to make the paper look whiter? (by reducing the yellows). Could papers have little or no OBAs but have quite a lot of shading agents, and could these be just as big a problem (as they may affect a wider part of the spectrum, and as we have no mechanism to compensate them out)?
Because shading agents are just dyes, you don't have to do anything - the normal profiling process takes it all into account. My guess is that shading agents would rarely be used on their own, but typically as an additional component to the FWA in the cheapest types of papers. They are easy to spot as a dip in the paper reflectance in mid wavelengths.
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Yes, having an instrument that can take two measurements with more and less UV provides a better way of estimating the quantum efficiency of the fluourescent agent, as well as its emission spectrum. This has nothing to do with correcting or not correcting a full gamut of colors.
Well, i1Profiler measures every spot color twice (with and without UV) in dual-scan mode. This means that the effect of fluorescence is known for the whole gamut. As this information is available, the software could (but perhaps doesn't) apply the compensation for each spot color. Then it gets the UV content of the target illuminant using the gray card and scales the data up or down as required.
If I understand you correctly, you are saying that the dual scan would give you a better way of computing the spectrum due to the OBA. Why would you need to measure anything except the paper white for that?
When you say 'quantum efficiency', what do you mean? Do you mean the varying effect of the UV on each spot color? If that is what you mean, then would this not be quite useful in correcting the full gamut?
If the full gamut is not corrected using this data, then how is it corrected? For example, how does Argyll do it? (since Argyll, at least currently, does not do a dual scan).
Robert
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Because shading agents are just dyes, you don't have to do anything - the normal profiling process takes it all into account. My guess is that shading agents would rarely be used on their own, but typically as an additional component to the FWA in the cheapest types of papers. They are easy to spot as a dip in the paper reflectance in mid wavelengths.
Thanks, that's good to know.
Robert
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Thanks, Robert, for the Northlight link.
That cleared up a lot in my understanding of what to look for and test within a printed sample. Those visual yellow/blue neutral patch testers in Keith's review photos on OBAs under different lights seems to support why I have to apply a reduction in the blue channel in Level's middle slider in Photoshop to get a better color match to my display.
Epson Ultra Premium Glossy appears at times depending how long I'm away from my 6500K display neutrality to be quite bright white just like my display. Lengthy edit sessions on the display don't change my perception of how blue this paper appears until I view it under my 5000K-ish daylight flotubes where it then appears warmer but the rest of the tonality of prints does appear bluer without the Level's blue channel reduction.
At least I get an idea of what and how all this needs to be done though I'm sure not as exacting as it should be based only on my visual observations.
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If I understand you correctly, you are saying that the dual scan would give you a better way of computing the spectrum due to the OBA. Why would you need to measure anything except the paper white for that?
Because the exact way that the incident UV and resulting blue light is filtered by the colorants in and on the medium is better measured than estimated, if you have the means to do so.
When you say 'quantum efficiency', what do you mean?
Technical term for how efficiently the fluorescent agent converts photons of UV into visible light.
If that is what you mean, then would this not be quite useful in correcting the full gamut?
Useful, but not essential. Given a spectral model of the Fluorescent agent, it's possible to then combine that with a model of how the colorants affect the media spectral reflectance, and arrive at a model of FWA augmented reflectance that accounts for the major effects. Naturally this variable correction applies to any color.
If you like, I can send you a copy of my 2003 paper on Argyll's FWA compensation. It's technical (and I have made refinements since then), but it conveys a lot of the essential logic of what it does.
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Epson Ultra Premium Glossy appears at times depending how long I'm away from my 6500K display neutrality to be quite bright white just like my display. Lengthy edit sessions on the display don't change my perception of how blue this paper appears until I view it under my 5000K-ish daylight flotubes where it then appears warmer but the rest of the tonality of prints does appear bluer without the Level's blue channel reduction.
I don't have the Epson Ultra Premium Gloss, but I would expect it to have quite a high OBA content, based on doing some tests, which you can see here:
(http://www.irelandupclose.com/customer/LL/Papers-OBA.jpg)
(right-click to view full size).
These are some papers I have lying around. The spectrum is plotted using the Argyll spotread utility. I've added some notes, based on my interpretation (which may not be entirely correct). At any rate, if I'm half-right, then you can see that most of the glossy and satin papers have quite a bit of OBAs (hump around 440nm), and most seem to have some shading agents (wide dip around 600nm).
I see that I've noted that the Hahnemuhle PhotoRag Ultrasmooth has no OBAs which isn't correct, but it doesn't have much.
In general the matte papers have little or no OBAs, the notable exceptions being the Hahnemulhle PhotoRag Bright White and Epson Archival Matte.
Robert
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Given a spectral model of the Fluorescent agent, it's possible to then combine that with a model of how the colorants affect the media spectral reflectance, and arrive at a model of FWA augmented reflectance that accounts for the major effects. Naturally this variable correction applies to any color.
If you like, I can send you a copy of my 2003 paper on Argyll's FWA compensation. It's technical (and I have made refinements since then), but it conveys a lot of the essential logic of what it does.
Thank you for the clarification.
If the paper is this one: "A Practical Approach to Measuring and Modelling Paper Fluorescence for Improved Colorimetric Characterisation of Printing Processes" then I've already purchased it. But I would be interested to see the refinements and I'm sure others on this forum would like to read it.
Robert
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If the paper is this one: "A Practical Approach to Measuring and Modelling Paper Fluorescence for Improved Colorimetric Characterisation of Printing Processes" then I've already purchased it. But I would be interested to see the refinements and I'm sure others on this forum would like to read it.
Yes, that's the one. The refinements are implementation detail - they wouldn't change the paper very much, even if I updated it, but they are reflected in the source code and behavior.
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These are some papers I have lying around. The spectrum is plotted using the Argyll spotread utility. I've added some notes, based on my interpretation (which may not be entirely correct).
Robert
Reading through this thread, as an owner of an iSis and i1Profiler, I wondered why my Canson Platine profile performed so well compared to others I had tried, some low-OBA papers, even with dual measurements.
I agree with you Robert that Platine is a 'magnificent paper', assuming you can embrace the warm white. I can and do. It is my #1 choice wherever possible.
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Reading through this thread, as an owner of an iSis and i1Profiler, I wondered why my Canson Platine profile performed so well compared to others I had tried, some low-OBA papers, even with dual measurements.
I agree with you Robert that Platine is a 'magnificent paper', assuming you can embrace the warm white. I can and do. It is my #1 choice wherever possible.
Yes, it's interesting to look at the spectrum response of these papers to see if this partially explains why we like some papers better than others. A paper that surprised me was the HP ID Satin - I have a roll that's been lying around for a few years and I didn't really consider it for anything more than proofing, but when I had another look at it I found that it's a really good heavy paper with a fine satin finish. Prints on it look good in pretty much any light ... and that's explained by the low amount of OBA in the paper. The paper also has a good white look, which is probably party due to the shading agents (as well as the relatively small amount of OBAs).
But I guess the main use of the spectrum plots is as a warning when using some papers: the Permajet Oyster, for example, really shouldn't be used unless the target illuminant is known.
Robert
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Was hoping someone could show what is considered an unacceptable print due to OBA's vs one without viewed under a light that makes them unacceptable. I can't find anything online to show me this.
I examined my mid '90's commercial press paper sampler from Potlatch and see that their papers have a slight yellowish amber (off white) tint next to my quite brilliantly brighter, bluish, less dingy Epson Ultra Premium Glossy viewed under the same lights I demonstrated previously.
The Potlatch sampler may have aged but then I didn't have the Epson paper to compare against as a new standard for white back then.
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Was hoping someone could show what is considered an unacceptable print due to OBA's vs one without viewed under a light that makes them unacceptable. I can't find anything online to show me this.
There's a lot of data on the Aardenburg website showing the effects of OBAs on paper white and the various colors following prolonged fading studies under illumination.
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Was hoping someone could show what is considered an unacceptable print due to OBA's vs one without viewed under a light that makes them unacceptable. I can't find anything online to show me this.
I examined my mid '90's commercial press paper sampler from Potlatch and see that their papers have a slight yellowish amber (off white) tint next to my quite brilliantly brighter, bluish, less dingy Epson Ultra Premium Glossy viewed under the same lights I demonstrated previously.
The Potlatch sampler may have aged but then I didn't have the Epson paper to compare against as a new standard for white back then.
Hi Tim,
I think what you're looking for is very subjective - what may be acceptable to one person may not be to another. Also it's not possible to get two papers with identical characteristics, one with and one without OBAs (obviously :)).
On the other hand, it's pretty easy to show the color shifts due to UV on a paper that has OBAs. Just illuminate the print with a light that has low UV (for example a Solux 4700K bulb) and then shine some UV on it using a UV torch (costs a few dollars only). If the print is on a paper that has no OBAs, the UV light will make no difference.
Once you can see what the UV does on a print that has OBAs, you could then view the print under blue sky daylight (which has plenty of UV) to see the effect.
A simple test to see if the paper has OBAs is to shine UV onto it in a totally dark room: the paper will look blue.
What would be more interesting really would be to do a print (on a paper that has OBAs) with no OBA compensation, then reprint with OBA compensation for a specific illuminant (which is known to have UV), and then view both under this illuminant. It's something I intend to do when I have some spare time ... not going to be soon though!
Robert
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There's a lot of data on the Aardenburg website showing the effects of OBAs on paper white and the various colors following prolonged fading studies under illumination.
I'm aware of OBA's and what they look like on blank, non-printed paper.
What I'm trying to get an idea from visual inspection is how OBA's cause color prints to look unacceptable and unappealing to the point it must be measured and profiled to improve the color or avoid the OBA paper all together. What would be even more helpful is to show a comparison of how OBA's actually change the look of color ink on paper vs how it's not changed on non-OBA paper.
Has anyone actually researched this with visual comparisons to show the benefits of avoiding printing color images on OBA paper or measuring and profiling to fix it?
I gather from the answers in this thread and what I see online no one is that concerned about it enough to show what this looks like. I'm trying to get an idea of just how subtle the effects are and see how technology such as a print profiling package can improve the results.
I'm also assuming that there are non-OBA papers that look just as bright pure white (like the Epson Ultra Premium Glossy) as ones with OBA's so the advice to avoid OBA paper will still not cause one to settle for printing on dingy looking, off white paper as I see in the Potlatch sampler.
Robert, I look forward to your research and the results on this issue.
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Has anyone actually researched this with visual comparisons to show the benefits of avoiding printing color images on OBA paper or measuring and profiling to fix it?
I gather from the answers in this thread and what I see online no one is that concerned about it enough to show what this looks like. I'm trying to get an idea of just how subtle the effects are and see how technology such as a print profiling package can improve the results.
I agree that it would be very useful to have tests that show the hue changes on a variety of papers that have OBAs under illuminants with different amounts of UV. But this could end up becoming a life's work ... and an expensive one at that. One would need a controlled environment, and it's not just the papers and the light, but also the inks (and how opaque) and profiles and printers. Then there's the problem of how to measure and report that information, not a trivial task either!. That's why avoiding papers with OBAs may be a smart move, or keeping to papers that have low OBAs.
One thing I do know is that the effect of lighting on pictures is huge ... even on papers that have no OBAs. I suspect that the 'answer' is a sort of recipe: for example:
High OBA Paper; Light: High UV, Cool White
OBA compensation
Warming filter
Taste and adjust seasoning
No OBA Paper; Light: Cool White
Warming filter
Taste and adjust seasoning
The other thing is to use few papers and get to know how they perform well.
I'm also assuming that there are non-OBA papers that look just as bright pure white (like the Epson Ultra Premium Glossy) as ones with OBA's so the advice to avoid OBA paper will still not cause one to settle for printing on dingy looking, off white paper as I see in the Potlatch sampler.
I would be VERY surprised if the Epson Ultra Premium Glossy doesn't have quite a lot of OBAs Tim. If you look at the Epson paper specs you'll see that they don't specify whether or not this paper has OBAs; however when a paper has none then they do state it (for example for the Exhibition Watercolor Paper Textured). It's the same for other paper manufacturers. So when the OEM/manufacturer does NOT specify that the paper has no OBAs, you can be pretty sure that it does. The only way I know of gauging how much is to measure the SPD as I've done with the sample set above.
Robert
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I agree that it would be very useful to have tests that show the hue changes on a variety of papers that have OBAs under illuminants with different amounts of UV.
I did not suggest this in my previous post at all.
I said one test to show how a printed color image whose appearance is affected by OBA paper viewed under any normal viewing light and how it appears being corrected or improved upon either by profiling or switching to printing the color image on a non-OBA paper. This would not be an expensive test to demonstrate this issue IMO.
Your suggestion that overall there are too many variables to consider in mitigating against this and the solutions offered makes futzing with this pretty much similar to taking a humidifier to the beach to dry out the air. It's a no win situation that's not worth the trouble of fixing. Of course every color print on any given paper will look drastically different under a variety of lights, but we don't make prints so they will be viewed under every light under the sun. That would be unmanageable and pointless.
I would be VERY surprised if the Epson Ultra Premium Glossy doesn't have quite a lot of OBAs Tim.
Sorry, I didn't write that clear enough. I know the Epson paper has OBA's>(I couldn't see its effect in the photo I posted previously). I mentioned it now as a comparison to how bright white it is compared to the 20 year old Potlatch paper sampler whose warm, yellowish amber off white is not a desirable look. The point I was making is that as long as there is something to compare against no "white" paper is going to exhibit the exact hue as intended which creates even more variables.
I still have no answer on how OBA paper changes the look of printed color viewed under any given light.
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I still have no answer on how OBA paper changes the look of printed color viewed under any given light.
Isn't the change of paper whiteness over time an even more important factor not to choose papers with OBA:s? The Epson Exhibition (here in Europe called Epson Traditional) changes its hue to a yellow-greenish tone, quite unattractive.
Stefan
www.korta.nu/profiler
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I still have no answer on how OBA paper changes the look of printed color viewed under any given light.
Tim, as part of the review work i did on the Hahnemuhle Photo Pearl, i tried to address that specific aspect. To summarise: The change to the perception is mainly dependent on 2 aspects, assuming a given print( so a constant in this test): the spectrum of the light, and its UV content. In my perception looking at prints, the combination of both aspects can vary from cool (f.i direct sunlight or even blueer the light from a blue sky) to warm (a ordinary halogen) and warmwith a cool touch ( a ordinary warm white LED) to the lighter parts (less ink) of a print.
A great way to test this is to take this OBC print from i1Profiler with its 4 columns of grey, and find a visual match with the testchart under every possible lighting condition you can get. Score the matching results, and you will see it can go all over the OBC print.
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Isn't the change of paper whiteness over time an even more important factor not to choose papers with OBA:s? The Epson Exhibition (here in Europe called Epson Traditional) changes its hue to a yellow-greenish tone, quite unattractive.
Stefan
www.korta.nu/profiler
Good point ... and one I hadn't thought of. Here's an article that talks about both OBAs and the Epson Exhibition: http://www.luminous-landscape.com/reviews/printers/epson_exhibition_fiber.shtml
Robert
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Of course every color print on any given paper will look drastically different under a variety of lights, but we don't make prints so they will be viewed under every light under the sun. That would be unmanageable and pointless.
Well really this is the whole point of not using papers with OBAs. As long as there is some white showing chromatic adaptation will to a large extent compensate for the different light sources as all the colors will shift proportionally. Admittedly, very spiky illuminants will mess this up ... but then we shouldn't be viewing prints under these lights.
With OBAs the shift in colors will not be proportional, so the relation between the colors may be badly affected.
My own feeling is that we can spend ages trying to pin this down, but the best solution is to use papers with no OBAs, or papers with very little OBAs. There are some really excellent papers available now with great gamut and DMax, so why use papers with OBAs? In my case, the only paper I use which has a fair amount of OBAs is the Canson Photo HiGloss ... and the only reason I use this paper is that I need a very smooth, heavy, gloss paper to laminate under acrylic. If anyone knows of a really good, very smooth, thick, opaque gloss paper with no OBAs I would be VERY grateful!
Robert
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With spectrometers that either have a UV cut filter or no UV light source at all, any compensation in the profile for OBA effect has to depend on an extrapolation from the spectral plot above the wavelengths said spectrometers can not measure. Enough meters that do not measure below 430 nm wavelength. A tricky method given the differences in OBA content between papers and differences in their whiteness.
The suggested measuring of the UV absorbance should on the other hand take into account that TiO2 whitening agent absorbs UV light too but its fluorescence does not occur in visual light but heat.
The safest way would be measuring with a non-UV cut spectrometer on OBA less papers. For a more predictable profile result, reduced color inconstancy in practice and more color constancy in time.
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
November 2014 update, 680+ inkjet media white spectral plots
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...In my perception looking at prints, the combination of both aspects can vary from cool (f.i direct sunlight or even blueer the light from a blue sky) to warm (a ordinary halogen) and warmwith a cool touch ( a ordinary warm white LED) to the lighter parts (less ink) of a print...
Again to clarify even further, are you just describing your perception of the change of hue to paper white ONLY or are you including the hue changes in the entire color image as well?
Did you look at the photo I posted of the white rose on OBA ridden Epson Ultra Prem Glossy and figure out whether the light or the OBA reacting to the light created all those paper white hue changes? Keep in mind that as long as you view that print under changing light and are able to compare them side by side as depicted in my photo, you'll ALWAYS see a change to hue to every paper manufactured whether it has OBAs or not.
Isn't the change of paper whiteness over time an even more important factor not to choose papers with OBA:s? The Epson Exhibition (here in Europe called Epson Traditional) changes its hue to a yellow-greenish tone, quite unattractive.
I have never seen that effect exhibited in all the papers I've come across in my entire 55 years. I've got paper items in my illustrators/graphic design portfolio that go back as far as the early '80's and published pieces as far back to the early '70's in my high school days that only slightly yellowed. In all those years I was never told to be concerned about OBA content for archival purposes as an artist. My Epson Ultra Premium Glossy inkjet prints have been hanging on my living room wall exposed to all forms of low level light for at least 5 years with no change to paper white or the ink.
So it's obvious that Epson Exhibition is one rare bird and should be avoided if it turns yellow-greenish over time. I don't know how anyone is going to be able to predict that will happen to any one particular OBA paper. I'm not worried my Epson Ultra Prem Glossy prints are going to turn yellow-greenish seeing 50 years from now, it'll be just as easy as it is now to do a reprint on better or different paper.
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With OBAs the shift in colors will not be proportional, so the relation between the colors may be badly affected.
I'm assuming you're referring to the relationship of the entire color image and paper white and not just the paper white, and if so, I'ld like to see a demonstration of this disproportional bad color relationship.
I have not seen this happen in any painting, color pastel drawing on paper or print of an image in all the paper media I've viewed in my lifetime as an art director/prepress production technician/graphic artist/illustrator/cartoonist.
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I'm assuming you're referring to the relationship of the entire color image and paper white and not just the paper white, and if so, I'ld like to see a demonstration of this disproportional bad color relationship.
I have not seen this happen in any painting, color pastel drawing on paper or print of an image in all the paper media I've viewed in my lifetime as an art director/prepress production technician/graphic artist/illustrator/cartoonist.
Well Tim, I have. I've had prints hanging on the fridge door from photos of our grandchildren taken at different ages as they progressed, in those days printed on Epson Enhanced Mstte (or whatever they are naming the stuff now - I'd never go back to it with today's paper choices). The OBA fades visibly within a couple of years - the older ones looked more yellow than the newer ones placed beside them, because as the OBA fades, more of the true paper colour shows through. The fading was quite even and did not seem to distort non-white colour, so it never really bothered me all that much, but nonetheless the change at least to the white was undeniable.
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Well Tim, I have. I've had prints hanging on the fridge door from photos of our grandchildren taken at different ages as they progressed, in those days printed on Epson Enhanced Mstte (or whatever they are naming the stuff now - I'd never go back to it with today's paper choices). The OBA fades visibly within a couple of years - the older ones looked more yellow than the newer ones placed beside them, because as the OBA fades, more of the true paper colour shows through. The fading was quite even and did not seem to distort non-white colour, so it never really bothered me all that much, but nonetheless the change at least to the white was undeniable.
Thanks for the heads up on Epson Enhanced Matte, Mark.
I have prints on Epson Prem Presentation Matte and haven't experienced fading and yellowing in the past 5 years but then I only use it for testing color gamut shifting and keep them covered among a stack of other papers.
I'ld still like to know if there are non-OBA papers that look just as bright white as Epson Ultra Prem Glossy. I don't have a whole collection of papers to compare, just Epson paper I buy at OfficeMax or Target.
I've got colored Canson Fine Art Paper for pastel drawing I keep in my walk-in closet in a flat file satchel and I'm sure they're OBA/acid free since they look the same as they did 30 years ago when I bought them at Herwecks art supply store in Houston, TX.
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Premium Presentation Matte is the new name for Enhanced Matte. AFAIK, same paper. There are Baryta luster papers available from several manufactures that are either OBA free or have very little.
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I'ld still like to know if there are non-OBA papers that look just as bright white as Epson Ultra Prem Glossy. I don't have a whole collection of papers to compare, just Epson paper I buy at OfficeMax or Target.
Tim, it's difficult to get a bright white paper in the absence of some type of chemical additive whether it's baryta, titanium dioxide (seldom used in paper making) or an OBA additive. OBAs are the cheapest way to go and that's commonly used in inexpensive Xerox paper. They also use the cheapest fluorescence agents in these uses and it doesn't matter if the paper turns yellow in a year or so as it is usually disposed of before then. I don't know the Epson paper that you mention so I cannot give you a decent answer. The two non-OBA papers that I have printed on are Museo Silver Rag and Canson Plantine Rag. Both are warm papers. I honestly don't think you can get a true bright white paper that doesn't have some type of additive. Baryta is pretty inert and you don't have the same issues as with OBAs.
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Tim, it's difficult to get a bright white paper in the absence of some type of chemical additive whether it's baryta, titanium dioxide (seldom used in paper making) or an OBA additive...
Titanium dioxide? That what I'ld add as an OBA going by my experience painting with it in acrylics.
I take it, it's toxic and/or too expensive as a paper additive?
I know it's a very stable and pure form of white and very bright. I can mix it with a pure carbon black and get perfect neutral, no off hues due to sulfur content in either paint.
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Tim, probably a Baryta like the Canson Baryta is as white as you'll get without OBAs (it has a little, but very little). The Barium Sulphate whitens the paper to some extent, as you know.
I started to do some experimentation but to be honest I have my doubts as to whether it's worth the effort. Here is a start:
(http://www.irelandupclose.com/customer/LL/OBA-test1.jpg)
(right-click to view full size)
All the SPDs are measured using an i1Pro2 and Argyll spotread.
The top image is the measurement of the paper white - as you can see, there is a lot of OBA in this paper.
The next two images are the SPD of a Solus 4700K and the SPD of the reflection off the paper illuminated by this lamp. Even though the Solux has very little UV (allegedly) it does seem that it has some as there's a hump around 450nm.
The bottom two images are the SPD of a fluorescent D65 tube and below that the SPD of the reflection off the paper illuminated by this lamp. If the spikes are ignored you can see that the readings below 500nm are significantly higher in the reflected SPD, showing the effect of the UV on the paper OBA.
The fact is that a print viewed under the Solux will look very different to it viewed under the fluorescent, naturally, OBAs and UV notwithstanding.
So the test would have to be under the same illuminant, and it would seem to me that the Solux is the better choice as it has a very smooth SPD.
So:
- profile the paper with and without OBC.
- print spot colors with the two profiles
- illumine both prints with the Solux and measure the reflected Lab color of each spot. If the OBC is working correctly then the Lab values of the OBC test print should be closer to the image Lab values.
Does that make sense, or is there an easier way (like photograph the two images side by side)?
It does seem like a lot of work!! Which may explain why not too many people have bothered.
Robert
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The fact is that a print viewed under the Solux will look very different to it viewed under the fluorescent, naturally, OBAs and UV notwithstanding.
So the test would have to be under the same illuminant, and it would seem to me that the Solux is the better choice as it has a very smooth SPD.
So:
- profile the paper with and without OBC.
- print spot colors with the two profiles
- illumine both prints with the Solux and measure the reflected Lab color of each spot. If the OBC is working correctly then the Lab values of the OBC test print should be closer to the image Lab values.
Does that make sense, or is there an easier way (like photograph the two images side by side)?
It does seem like a lot of work!! Which may explain why not too many people have bothered.
Robert
That's not the test I asked for twice already, Robert, so I don't know why you keep going through the trouble of even responding with your own setup. If it's because you're trying to eliminate any subjectivity by only showing spot colors with one light source (Solux) which the majority of the public at large don't view prints under, then you're setup is not a reflection of real world conditions of how humans view a printed color image on paper with or without OBA's.
We don't photograph in a lab.
We don't view prints in a lab.
And we don't print so we're within specs of spectral plots and spot color Lab numbers. I and most folks I know don't view prints this way so a controlled lab setup is pointless.
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That's not the test I asked for twice already, Robert, so I don't know why you keep going through the trouble of even responding with your own setup. If it's because you're trying to eliminate any subjectivity by only showing spot colors with one light source (Solux) which the majority of the public at large don't view prints under, then you're setup is not a reflection of real world conditions of how humans view a printed color image on paper with or without OBA's.
We don't photograph in a lab.
We don't view prints in a lab.
And we don't print so we're within specs of spectral plots and spot color Lab numbers. I and most folks I know don't view prints this way so a controlled lab setup is pointless.
I think it's easy to get carried away with technical analyses and forget to relate the results to the difference they make to real world outcomes and contexts. That said, if you're trying to understand what's happening under the hood - for whatever it's worth - scientific procedure is the only way to go.
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I think it's easy to get carried away with technical analyses and forget to relate the results to the difference they make to real world outcomes and contexts. That said, if you're trying to understand what's happening under the hood - for whatever it's worth - scientific procedure is the only way to go.
I already know what's happening scientifically under the hood, Mark.
I'm trying to see how it manifests in the real world and I'm not seeing it as much an issue in this regard to justify the amount of work and concern involved to fix it.
If I could see one good example that would get me to say..."Oh yeah, we need to go to these lengths to head this off before our client wants their money back because their print looks like crap under their lights and/or the paper white has turned a funky color after a year hanging next to window light."...then I'ld finally get a good idea about the concern and reasons for fixing it.
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I already know what's happening scientifically under the hood, Mark.
..............
You may, but there are others..........
At the same time, I hear you - I too think it's productive to have a practical focus on outcomes that matter.
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The common whitening agent for the PE barrier layer at the print side of RC paper is TiO2 in one of its crystal versions, the back side PE barrier is transparent. I suspect at least some Moab natural fine art papers have TiO2 whitening agents; UV absorption but no fluorescence in the visual spectrum. I expect more papers to have TiO2 as part of a mix of whitening agents, less so where OBA content should not have competition in UV absorption, barite is then a better companion. TiO2 is quite common in paper production. I'm not aware of toxicity of TiO2 in this application, in sun creams it is an issue.
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
November 2014 update, 680+ inkjet media white spectral plots
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That's not the test I asked for twice already, Robert, so I don't know why you keep going through the trouble of even responding with your own setup. If it's because you're trying to eliminate any subjectivity by only showing spot colors with one light source (Solux) which the majority of the public at large don't view prints under, then you're setup is not a reflection of real world conditions of how humans view a printed color image on paper with or without OBA's.
Well Tim, I have no idea how you would go about doing the test you want (and in particular how I could show this to you over the web).
If you want to see the effect of OBC on a particular paper then you have to print a sample both with and without OBC and see if there's a significant difference. You can't do OBC without specifying the light source, so whether that light source is a Solux 4700K, cheapo fluorescent, or whatever, makes no difference, as long as you specify which it is.
Doing a comparison between a paper that has OBA and one that doesn't isn't going to be of much use because the paper characteristics and the profiles will be different ... so of course you will get a variation.
At any rate, I have done a test with a spectrum that I have posterized. Under the Solux 4700K I can see no difference between the OBC print and the non-OBC print.
So I then tried to produce an OBC profile for a fluorescent (from the saved scan data) as this may have more UV ... but i1Profiler screws up the profile completely. Producing a non-OBC profile from the saved scan data works fine ... so there's definitely a major bug here. I'll report it to XRite.
The alternative would be to use Argyll ... but I've run out of time.
Anyway, Tim, why don't you spell out the steps you want in your test ... and then why don't you do it yourself? I would be very interested to see what you come up with.
Robert
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TiO2 is quite common in paper production. I'm not aware of toxicity of TiO2 in this application, in sun creams it is an issue.
It's commonly used in sunscreens and has some other cosmetic applications as well so toxicity is not an issue.
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It's commonly used in sunscreens and has some other cosmetic applications as well so toxicity is not an issue.
In sun screens the TiO2 particles are covered with silicate for a reason.
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2014 update, 700+ inkjet media white spectral plots
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Well, I've done a test using Argyll. I've produced 3 profiles for the high-OBA Permajet Oyster paper:
- Standard D50 illuminant
- Fluorescent D65 illuminant
- Fluorescent D65 illuminant with OBC
Here is a photograph of the 3 test strips, photographed under the D65 fluorescent:
(http://www.irelandupclose.com/customer/LL/FWA-Test-Image.jpg)
(right-click to view full size).
I've blurred the image slightly to remove any local variations due to noise etc.
You can get the tif image here: http://www.irelandupclose.com/customer/LL/FWA-Test-Image.tif (http://www.irelandupclose.com/customer/LL/FWA-Test-Image.tif)
There is a lightness and hue shift between the strips. The D50 colors are lighter and generally have more magenta and yellow than the D65-illuminant image. This is also true between the D50 and D65-OBC image, but the differences are slightly greater. This is a bit puzzling as I would have expected the OBC-compensated image to have more yellow (since the OBA should be giving a blue-white tint and to compensate for this the OBC should add yellow ... to my mind, that is). I'll ask Graham Gill for his view on this.
So, based on this and with the Argyll profile, I would say that the differences are subtle and more pronounced on some colors than others. Using and illuminant-compensated profile certainly seems to produce better results than using a standard D50-illuminant profile. There are further slight improvements with OBC. With Argyll there is no additional effort in producing the OBC profile over the illuminant-compensated profile, so why not do it? Of course the target illuminant needs to be known.
Between D50 and D65 there isn't a huge difference, but if the target illuminant was a warm incandescent then the differences would probably be more significant.
Anyway ... I hope that's of interest and gives some food for thought. My general feeling is that for most images using a standard D50 profile is fine as it will cover a good range of illuminants. FWA compensation is probably only worth doing for specific images that just don't look right under the target illuminant.
Robert
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Well, I've done a test using Argyll. I've produced 3 profiles for the high-OBA Permajet Oyster paper:
- Standard D50 illuminant
- Fluorescent D65 illuminant
- Fluorescent D65 illuminant with OBC
Here is a photograph of the 3 test strips, photographed under the D65 fluorescent:
(http://www.irelandupclose.com/customer/LL/FWA-Test-Image.jpg)
(right-click to view full size).
I've blurred the image slightly to remove any local variations due to noise etc.
You can get the tif image here: http://www.irelandupclose.com/customer/LL/FWA-Test-Image.tif (http://www.irelandupclose.com/customer/LL/FWA-Test-Image.tif)
There is a lightness and hue shift between the strips. The D50 colors are lighter and generally have more magenta and yellow than the D65-illuminant image. This is also true between the D50 and D65-OBC image, but the differences are slightly greater. This is a bit puzzling as I would have expected the OBC-compensated image to have more yellow (since the OBA should be giving a blue-white tint and to compensate for this the OBC should add yellow ... to my mind, that is). I'll ask Graham Gill for his view on this.
So, based on this and with the Argyll profile, I would say that the differences are subtle and more pronounced on some colors than others. Using and illuminant-compensated profile certainly seems to produce better results than using a standard D50-illuminant profile. There are further slight improvements with OBC. With Argyll there is no additional effort in producing the OBC profile over the illuminant-compensated profile, so why not do it? Of course the target illuminant needs to be known.
Between D50 and D65 there isn't a huge difference, but if the target illuminant was a warm incandescent then the differences would probably be more significant.
Anyway ... I hope that's of interest and gives some food for thought. My general feeling is that for most images using a standard D50 profile is fine as it will cover a good range of illuminants. FWA compensation is probably only worth doing for specific images that just don't look right under the target illuminant.
Robert
That test strip image doesn't tell me how a color photograph of a real scene with a wide range of colors will look on white paper whether it has OBA's or not. I can't see any of the effects from light or OBA in that strip.
You can talk six ways to Sunday about this and still not communicate the real importance of mitigating against these optical issues unless you show it in a real world situation.
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That test strip image doesn't tell me how a color photograph of a real scene with a wide range of colors will look on white paper whether it has OBA's or not. I can't see any of the effects from light or OBA in that strip.
You can talk six ways to Sunday about this and still not communicate the real importance of mitigating against these optical issues unless you show it in a real world situation.
Well, we'll have to differ there Tim. In my view you first need to demonstrate whether or not there's a difference under controlled conditions, then when you've understood what is happening (if anything) you can move on to an actual photograph of a scene.
What the photograph of the three strips above shows is that there is only a marginal difference ... with this particular illuminant, and this particular paper, and this particular profile. Printing a real-world scene would have shown the same, but it would have been much more difficult to see the differences.
What I don't know at the moment is whether the very slight differences on the three strips is due to the OBC not being very effective, or because there's not much UV in the illuminant (quite possibly the reason from what I now understand about the amount of UV in off-the-shelf strip lights). What I need to do is to try to find out how to estimate the UV in an illuminant, and then pick a typical illuminant that does have quite a lot of UV and repeat the experiment.
What I don't understand is why you don't try the test your way ... at least then we would have two approaches to the problem and perhaps yours would prove move conclusive.
Robert
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What I don't understand is why you don't try the test your way ... at least then we would have two approaches to the problem and perhaps yours would prove move conclusive.
Because I don't have access to non-OBA inkjet paper. I'm only using Epson Ultra Prem Glossy with OBA which didn't change the look that much as evident in the photo of the white rose print demo I posted earlier.
If you're suggesting I do the same test with a print of an image with a wide range of colors on the same Epson paper viewed under the same variety of lights as in the photo, that I can do. I do have to wait for overcast light which according to local weather forecast may be tomorrow. I don't want to view under lights where there is a full blue canopy sky from a bright sunny day.
But I was hoping someone would have another brand of OBA paper where it acted on the color differently than the Epson viewing under a variety of lights. It seems so far from folk's responses on this thread their experiences are different from what I depicted in the photo demo suggesting not all OBAs are alike in this regard.
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Well, I've done a test using Argyll. I've produced 3 profiles for the high-OBA Permajet Oyster paper:
- Standard D50 illuminant
- Fluorescent D65 illuminant
- Fluorescent D65 illuminant with OBC
Here is a photograph of the 3 test strips, photographed under the D65 fluorescent:
Hi Robert,
I'm not sure what you hoped to show. For a start, the level of UV in a normal fluorescent light is typically quite low - it may even be lower than that you are getting from the Solux (which I am presuming is what you are using for your "D50" ?). Second, if a print is setup for D50, I'm not sure what the point of observing it under the D65 is - it can be quite tricky to figure out what to expect.
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Hi Robert,
I'm not sure what you hoped to show. For a start, the level of UV in a normal fluorescent light is typically quite low - it may even be lower than that you are getting from the Solux (which I am presuming is what you are using for your "D50" ?). Second, if a print is setup for D50, I'm not sure what the point of observing it under the D65 is - it can be quite tricky to figure out what to expect.
Hi Graeme,
Well, what I'm trying to demonstrate (for myself) is that a print with OBC will look better than a print without OBC under the target illuminant. So on the test image above, the top strip has OBC for the fluorescent lamp, the middle strip does not, but does have illumination compensation for the same fluorescent lamp. There is a difference between them, but it is very small - quite possibly because the fluorescent has little UV.
The D50 strip at the bottom is there to attempt to demonstrate what the effect of viewing an image profiled to the standard illuminant compares to images that have illumination compensation and OBA compensation. The reason for that is that if the differences are significant then it makes more sense to use IC/OBC when profiling a paper. If the differences are minor/insignificant, then why bother going to the trouble? ... just let chromatic adaptation handle it.
Is there some way, using Argyll, to estimate the level of UV in the illuminant? Here are plots from illumread for the fluorescent lamp:
(http://www.irelandupclose.com/customer/LL/IllumRead-Fluorescent-D65.jpg)
Robert
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Because I don't have access to non-OBA inkjet paper. I'm only using Epson Ultra Prem Glossy with OBA which didn't change the look that much as evident in the photo of the white rose print demo I posted earlier.
If you're suggesting I do the same test with a print of an image with a wide range of colors on the same Epson paper viewed under the same variety of lights as in the photo, that I can do. I do have to wait for overcast light which according to local weather forecast may be tomorrow. I don't want to view under lights where there is a full blue canopy sky from a bright sunny day.
But I was hoping someone would have another brand of OBA paper where it acted on the color differently than the Epson viewing under a variety of lights. It seems so far from folk's responses on this thread their experiences are different from what I depicted in the photo demo suggesting not all OBAs are alike in this regard.
Hi Tim,
Yes, if you could photograph the image with high UV/ low UV so that we can compare them that would be very useful. How would you set up the test? It would seem difficult to me to take a photograph of two images with very different illuminants for comparison purposes, as the color of the light will be completely different.
Perhaps the test we should be looking at is either:
- photograph the image under the lamp, then put a UV filter over the lamp and take the photograph again, with exactly the same settings on the camera
- photograph the image under the lamp, then add UV with a blacklight torch and take the photograph again, with exactly the same settings on the camera
That way the only difference between the photos would be the UV.
What do you think?
Robert
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Hi Tim,
Yes, if you could photograph the image with high UV/ low UV so that we can compare them that would be very useful. How would you set up the test? It would seem difficult to me to take a photograph of two images with very different illuminants for comparison purposes, as the color of the light will be completely different.
Perhaps the test we should be looking at is either:
- photograph the image under the lamp, then put a UV filter over the lamp and take the photograph again, with exactly the same settings on the camera
- photograph the image under the lamp, then add UV with a blacklight torch and take the photograph again, with exactly the same settings on the camera
That way the only difference between the photos would be the UV.
What do you think?
Robert
I disagree with the what appears to be your setup for unnecessary meticulousness for a real world demonstration of how a print will appear on OBA paper viewed under a wide range of lighting.
My previous photo of the white rose demonstrated how CMYK inkjet neutrals blend into the bright white of the OBA paper appear unaffected by the OBA viewed under these lights which is the reason I chose the white rose image. If OBA's affected perception of even neutral mixes of CMYK inkjet ink it would've shown up, but it didn't.
But a full color image having mostly primaries, warm earthen and cool pastel tones might show whether the OBA's shift the hues in these colors which I doubt since it didn't affect neutral CMYK which lays down less ink to allow more of the OBA paper white to show through.
Of course maybe a particular full saturation lay down of printed yellow on top of the OBA white might induce some spectral reflectance distortion under different lights. But then there's the other problem in determining whether the holes in the spectrum of lighting (CFL's) would be causing this where the yellow may appear a bit greenish. Is it the OBA's doing this or the light or a combination of both?
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My previous photo of the white rose demonstrated how CMYK inkjet neutrals blend into the bright white of the OBA paper appear unaffected by the OBA viewed under these lights which is the reason I chose the white rose image. If OBA's affected perception of even neutral mixes of CMYK inkjet ink it would've shown up, but it didn't.
Tim, I went back over the topic to have a look at your rose image and I think you forgot to include it in your post. Could you do it now, so I can see what you're getting at?
Robert
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Tim, I went back over the topic to have a look at your rose image and I think you forgot to include it in your post. Could you do it now, so I can see what you're getting at?
Robert, it's attached to Reply #46 of this thread (http://www.luminous-landscape.com/forum/index.php?topic=95251.msg779508#msg779508).
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Robert, it's attached to Reply #46 of this thread (http://www.luminous-landscape.com/forum/index.php?topic=95251.msg779508#msg779508).
I can't see it Tim ...
Out of interest, I've taken a few M1/M2 spot measurements using i1Profiler:
Copier paper gives:
M1 Lab readings of 92, 2.5,-9.7
M2 Lab readings of 91,0.6,-3.8
Canson Baryta gives:
M1 Lab readings of 98, 0.2,-1.3
M2 Lab readings of 98,-0.4, 1.1
Canson PhotoHiGloss gives:
M1 Lab readings of 95, 0.6,-6.4
M2 Lab readings of 95,-1.1, 0.3
Permajet Oyster gives:
M1 Lab readings of 95, 1.8,-14.8
M2 Lab readings of 94,-1.1,-1.9
This pretty much confirms the plots I posted further up: the Baryta has very low OBAs, but the PhotoHiGloss has quite a bit ... and the Permajet Oyster is through the roof (not a paper one should ever use!). Interestingly, the Baryta has a very high L value, so even though it has very little OBAs it's a very bright paper.
I also tested some papers like the Platine which are claimed to have no OBAs and the tests concur.
Robert
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Robert, you say you can't see the image I posted? Or you can't see the results I was talking about in the image?
If you can't see the image at all, then you may need to use another browser or set your preferences to allow attachments or ask the administrator of these forums what setting in your LuLa profile turns on viewing or allows attachments.
I've never had a problem viewing images uploaded from anyone in this forum going on several years.
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Robert, you say you can't see the image I posted? Or you can't see the results I was talking about in the image?
If you can't see the image at all, then you may need to use another browser or set your preferences to allow attachments or ask the administrator of these forums what setting in your LuLa profile turns on viewing or allows attachments.
I've never had a problem viewing images uploaded from anyone in this forum going on several years.
It would been a better test if you had included a light gray area and white balanced your images on that area. As our vision adapt to the ambient light conditions, we will see a gray area as gray.
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Robert, you say you can't see the image I posted?
I couldn't see the image at all. I've gone in and out of my preferences and even though I changed nothing I can now see the attachment! Maybe a kind administrator fixed it while I was not watching :)
It would been a better test if you had included a light gray area and white balanced your images on that area. As our vision adapt to the ambient light conditions, we will see a gray area as gray.
Yes, I agree. A gray card & white balancing is really needed. The overcast sun images do seem to show blueness from OBAs, but that could just be a white-balance problem.
Robert
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Hi Tim,
Yes, if you could photograph the image with high UV/ low UV so that we can compare them that would be very useful. How would you set up the test? It would seem difficult to me to take a photograph of two images with very different illuminants for comparison purposes, as the color of the light will be completely different.
Perhaps the test we should be looking at is either:
- photograph the image under the lamp, then put a UV filter over the lamp and take the photograph again, with exactly the same settings on the camera
- photograph the image under the lamp, then add UV with a blacklight torch and take the photograph again, with exactly the same settings on the camera
That way the only difference between the photos would be the UV.
What do you think?
Robert
Printer color mode, application CM. Make a B&W "real world" print on a high OBA content paper that shows the grey tone range without hue deviations from paper white to black. Say for the Solux "D50" with the UV-cut filter condition. Will be difficult enough BTW with the usual warm carbon black ink. Then do the same with OBC for the normal Solux "D50" condition. There is no need to put the two samples next to one another in both light conditions, the B&W print will have enough reference in the total tone range. The Permajet Oyster is a high OBA content paper, one from the Mitsubishi stable most likely. Try the same with a paper without or with little OBA content. Way more color constancy in changing light conditions. With or without OBC, a B&W print on a paper with high OBA content depends much more on color constancy in the illumination.
For OBA free papers there is in my experience something else happening too in B&W prints; the higher the white reflection of a paper is, the more the illumination light color dominates, which still affects the ink mixes but less the paper white. OBA free papers with high light reflection tend to be more neutral. With lower white reflection the paper "white" color is in competition with the color of the illumination light and can create more color constancy for changing light conditions. Eyes should adapt, they do more in color prints with a white or grey reference, in B&W the total tone range is the reference.
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2014 update, 700+ inkjet media white spectral plots
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Printer color mode, application CM. Make a B&W "real world" print on a high OBA content paper that shows the grey tone range without hue deviations from paper white to black. Say for the Solux "D50" with the UV-cut filter condition. Will be difficult enough BTW with the usual warm carbon black ink. Then do the same with OBC for the normal Solux "D50" condition. There is no need to put the two samples next to one another in both light conditions, the B&W print will have enough reference in the total tone range. The Permajet Oyster is a high OBA content paper, one from the Mitsubishi stable most likely. Try the same with a paper without or with little OBA content. Way more color constancy in changing light conditions. With or without OBC, a B&W print on a paper with high OBA content depends much more on color constancy in the illumination.
For OBA free papers there is in my experience something else happening too in B&W prints; the higher the white reflection of a paper is, the more the illumination light color dominates, which still affects the ink mixes but less the paper white. OBA free papers with high light reflection tend to be more neutral. With lower white reflection the paper "white" color is in competition with the color of the illumination light and can create more color constancy for changing light conditions. Eyes should adapt, they do more in color prints with a white or grey reference, in B&W the total tone range is the reference.
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2014 update, 700+ inkjet media white spectral plots
Hi Ernst,
Thanks for the link and suggestions. Here is a test on the (horrible!) Permajet Oyster under slightly cloudy daylight and under Solux 4700K. As you can see the Solux has very little UV (it's SPD is quite smooth, so the paper is indicating some UV, but nothing compared to sunlight).
The paper seems to have some sort of filter for blue light under 420nm or so (the Solux does show a reasonable amount of blue at 400nm).
I can't see OBC in any way being able to compensate for this sort of difference! Really, the best approach is to use very low or zero OBA paper and profile for the target illuminant if at all possible.
Robert
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It would been a better test if you had included a light gray area and white balanced your images on that area. As our vision adapt to the ambient light conditions, we will see a gray area as gray.
Apparently you underestimate my skill at editing and seeing what's right next to my display. I've been doing it for quite a long time. I made it look as it appears to me.
Also you're premise and logic indicates we can't trust our eyes and if that's the case then we can't trust whether OBAs affect the aesthetic appearance of a color print so there's no point measuring for it since we won't see it due to the fact we can't trust what we see.
That's what you get with circular logic. You can't deny the fact we humans rely on functionality and not just theory and/or some spectro measurement. We don't make or appreciate the aesthetics of a print derived and defined from spectrophotometry.
Posting my image is being disregarded and not even looked at anyway since this thread has gotten over 5000 views and my OBA image sample has gotten 12 views.
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Apparently you underestimate my skill at editing and seeing what's right next to my display. I've been doing it for quite a long time. I made it look as it appears to me.
Also you're premise and logic indicates we can't trust our eyes and if that's the case then we can't trust whether OBAs affect the aesthetic appearance of a color print so there's no point measuring for it since we won't see it due to the fact we can't trust what we see.
I don't underestimate anything. I don't know you, haven't seen any work from you. I'm just describing the way that I have done a similar test. And I suggested that you used a gray card without any OBA, as a Passport. And of course we can't trust our eyes, as our colour perception adapts to the lighting condition in a split millisecond.
When you do a test you try to find a way to keep all variables constant, except for the subject that you are evaluating. In this test I presumed that you wanted to see only how the OBA content in different papers affected the colours under light with high or low UV content.
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Apparently you underestimate my skill at editing and seeing what's right next to my display. I've been doing it for quite a long time. I made it look as it appears to me.
Also you're premise and logic indicates we can't trust our eyes and if that's the case then we can't trust whether OBAs affect the aesthetic appearance of a color print so there's no point measuring for it since we won't see it due to the fact we can't trust what we see.
That's what you get with circular logic. You can't deny the fact we humans rely on functionality and not just theory and/or some spectro measurement. We don't make or appreciate the aesthetics of a print derived and defined from spectrophotometry.
Posting my image is being disregarded and not even looked at anyway since this thread has gotten over 5000 views and my OBA image sample has gotten 12 views.
Yep, I think that's a valid point. I try to have some paper white in the image, either as part of the image or as a border, and that does make a real difference to the qualitative impression, I think. Today, for example, I had a customer who thought a framed print that had a white border (the paper) looked much better than the same print, in the same frame, but with a mat instead of the paper border. Things like that can have so much bigger an impact than the usually very minor color shifts due to OBAs (especially if one uses papers with no OBAs ;)).
Still, what I find is that I always learn something from these discussions ... in the case of this one, I think I've a better understanding of the papers I use than I did before; and I understand a bit better the reasons behind my dislike for the papers that I didn't like. It hasn't changed anything really as I will continue to use the papers I like and continue not to use the papers I didn't like, but what it does mean is that I will have a better idea of what to look for and what to avoid when I next need a new paper.
Having said that ... I'm a bit surprised that your images (which I eventually did manage to view :)) are shown as you saw them because I think your eyes would have compensated much more for the different lights. If your eyes did not, and if this is really what you saw, then I would suggest you get a new paper because the color shifts would seem unacceptable to me. Even with a paper pickled with OBAs like the Permajet Oyster, it's surprising the extent to which the eye adapts to different illuminants.
Robert
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Even with a paper pickled with OBAs like the Permajet Oyster, it's surprising the extent to which the eye adapts to different illuminants.
Robert
A single print without any comparator will always look fine assuming the image is processed OK. The eye adapts to what it sees. Where we begin to see vast differences is when the same image printed on different papers is compared. The eye/brain axis responds differently and of course personal preferences will always come into play here. One can print on matte papers with perfectly acceptable and sometimes pleasing results even though the paper gamut is not as large as a gloss paper. The eye adapts to the color/monochrome shadings. The same thing goes for different illuminants.
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I don't underestimate anything. I don't know you, haven't seen any work from you. I'm just describing the way that I have done a similar test. And I suggested that you used a gray card without any OBA, as a Passport. And of course we can't trust our eyes, as our colour perception adapts to the lighting condition in a split millisecond.
When you do a test you try to find a way to keep all variables constant, except for the subject that you are evaluating. In this test I presumed that you wanted to see only how the OBA content in different papers affected the colours under light with high or low UV content.
I posted what I saw. It's that simple. This is not a scientific endeavor. We don't create prints by subjecting it to scientific scrutiny. If you want to turn it into a science project, knock yourself out. A digital camera is not a precise scientific instrument and image reproduction on paper can't be tested using exacting science. If you can't understand that, then I'm not interested in what you have to offer in moving this thread forward.
None of the info in this thread has helped me one bit.
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None of the info in this thread has helped me one bit.
OK, we hear what you are saying. I can say that constructive advise is something that helped me to improve my photography and that forums like LuLa has accelerated this. But if you don't understand the suggestions and call that scientific scrutiny I think that a. you don't understand what scientific scrutiny requires b. you don't understand the simple suggestions that we have placed to improve your interesting test.
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A single print without any comparator will always look fine assuming the image is processed OK. The eye adapts to what it sees.
I do agree to some extent. However what got me involved in this thread is that I printed a photograph of some poppies that I had painted (below) and looking at it under a 6500K fluorescent it really didn't look right - there was much too much blue in the magentas (to my mind). I then looked at the print under a warmer light and I thought it looked fine. The paper had no OBAs.
I find that images that have few fairly saturated colors tend to look better under particular illuminants. I know that the theory is that chromatic adaptation should take care of the illuminant, given a few seconds for the eye to adjust, but I don't personally buy in to that totally. It could be, for example, that the spikes in the fluorescent were hitting the colors in the image at just the wrong points. Perhaps chromatic adaptation works best when the shape of the illuminant SPDs is smooth and the only difference is the color balance.
Robert
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I do agree to some extent. However what got me involved in this thread is that I printed a photograph of some poppies that I had painted (below) and looking at it under a 6500K fluorescent it really didn't look right - there was much too much blue in the magentas (to my mind). I then looked at the print under a warmer light and I thought it looked fine. The paper had no OBAs.
Robert
This is another problem, more like metameric failure. Paintings, especially aquarelles are a pain in ... to reproduce correctly. It takes a lot of tweaking to get it right, and you have to know under which light conditions the final print is going to be seen under. The different profiles in ImagePrint is a big help here.
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...I find that images that have few fairly saturated colors tend to look better under particular illuminants. I know that the theory is that chromatic adaptation should take care of the illuminant, given a few seconds for the eye to adjust, but I don't personally buy in to that totally. It could be, for example, that the spikes in the fluorescent were hitting the colors in the image at just the wrong points. Perhaps chromatic adaptation works best when the shape of the illuminant SPDs is smooth and the only difference is the color balance.
Robert
Really nice painting, Robert. Didn't know you had this talent.
That was helpful of you posting the photo sample of an image reproduced on non-OBA paper. Was wondering whether that paper looks less neutral white (off white/slightly yellowish) placing it next to paper with OBA (overlap comparison) and whether the two papers will exhibit varying hue shifts under different lights.
The Epson Ultra Prem Glossy with OBAs exhibited a more pinkish/violet blue (over cyan blue) in the overcast light on my front porch (seen in my sample photo) more than I'ld expected. It was almost a shock to see it shift hue so severely right after opening my front door to see the neutral bright white I'ld adapted to under home viewing light which is a mix of a bit of open window light filter by white plastic blinds and 5000K daylight LED and fluorescent.
As for your painting looking odd under 6500K fluorescent, I'ld have to go with the spiky spectra as the cause. I haven't come across any 6500K fluorescent that made anything look good. Out of all the CFL's I've tried Alzo 5500K CRI 95 is the best so far, but it makes saturated cadmium yellows look lemon yellow (increase in cyan).
And for flotubes a combination of T8 18in. 5000K Philips Natural Sunshine and 5000K GE Chroma 50s (Sunshine labeled) keeps color distortion to a minimum but do give off a slight greenish warmth after long edits adapting to a 6500K neutral calibrated display.
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That was helpful of you posting the photo sample of an image reproduced on non-OBA paper. Was wondering whether that paper looks less neutral white (off white/slightly yellowish) placing it next to paper with OBA (overlap comparison) and whether the two papers will exhibit varying hue shifts under different lights.
The Epson Ultra Prem Glossy with OBAs exhibited a more pinkish/violet blue (over cyan blue) in the overcast light on my front porch (seen in my sample photo) more than I'ld expected. It was almost a shock to see it shift hue so severely right after opening my front door to see the neutral bright white I'ld adapted to under home viewing light which is a mix of a bit of open window light filter by white plastic blinds and 5000K daylight LED and fluorescent.
As for your painting looking odd under 6500K fluorescent, I'ld have to go with the spiky spectra as the cause. I haven't come across any 6500K fluorescent that made anything look good. Out of all the CFL's I've tried Alzo 5500K CRI 95 is the best so far, but it makes saturated cadmium yellows look lemon yellow (increase in cyan).
And for flotubes a combination of T8 18in. 5000K Philips Natural Sunshine and 5000K GE Chroma 50s (Sunshine labeled) keeps color distortion to a minimum but do give off a slight greenish warmth after long edits adapting to a 6500K neutral calibrated display.
Hi Tim,
Here's a comparison between 4 papers, two with no OBAs, one with just a bit and one with quite a lot, taken first under cloudy sky then under Solux. There's not much to it, but visually there's no color shift on the papers without (or with little) OBAs, whereas the Photo HiGloss has a noticeable shift towards magenta/blue under the sky. I've included Lab values, but I'm not sure that they help much as I hand-held the Solux lamp and the illumination wasn't even over the paper.
Still, you can see quite clearly how much whiter/bluer the HiGloss paper is compared to the others.
When you say a combination of the Philips and GE tubes, do you mean to use both together?
Robert
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This is another problem, more like metameric failure. Paintings, especially aquarelles are a pain in ... to reproduce correctly. It takes a lot of tweaking to get it right, and you have to know under which light conditions the final print is going to be seen under. The different profiles in ImagePrint is a big help here.
Stefan, do you have some idea why the watercolors are more problematic? After all, once you've photographed them and printed them, you're back to inkjet inks, so you would think they would be no different to photographs. Or is it (as I suspect on the painting I posted) that the very limited palette with saturated colors is what makes the color shifts so noticeable? In which case perhaps watercolors with more subdued colors should be easier to reproduce?
Robert
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...When you say a combination of the Philips and GE tubes, do you mean to use both together?
Robert
Yes, I have both installed in a 2 tube desk lamp because the Philips has a noticeable magenta pigmented phosphor that aids in filtering the GE's noticeably greenish yellow spike on warm hues such as skin tone and oranges. IOW they balance each other out more or less. They're still not perfect but it's the best I've found in small T8's that install in available desk lamps and fixtures.
And thanks for going to the trouble of photographing and posting the OBA paper sampler comparison. I take it that non-OBA's don't look slightly yellow/beige like my Potlatch paper sampler which may be due to 20 years of aging.
Took some shots of a color print on Epson Ultra Prem Glossy next to a color print on the Potlatch sampler lit under both overcast and Alzo 5500K CFL. As you'll note the overcast light brings out the color distinctions between the different finishes in the paper where the Alzo CFL does not. I have no idea if the Potlatch paper has OBAs. I don't have a black light or measuring device to test.
But I find this demonstration points to another variable introduced by the type of light used that can bring out certain reflective characteristics that haven't been readily studied. Note that the Solux 4700K halogen (see photo below) exhibits the same color distinction between papers with different finishes as does the overcast light. This may be caused by the full spectrum qualities of both lights but I'ld think it would be hard to predict consistently whether this is the case considering the different paper finishes may have some part in it.
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Took some shots of a color print on Epson Ultra Prem Glossy next to a color print on the Potlatch sampler lit under both overcast and Alzo 5500K CFL. As you'll note the overcast light brings out the color distinctions between the different finishes in the paper where the Alzo CFL does not. I have no idea if the Potlatch paper has OBAs. I don't have a black light or measuring device to test.
But I find this demonstration points to another variable introduced by the type of light used that can bring out certain reflective characteristics that haven't been readily studied. Note that the Solux 4700K halogen (see photo below) exhibits the same color distinction between papers with different finishes as does the overcast light. This may be caused by the full spectrum qualities of both lights but I'ld think it would be hard to predict consistently whether this is the case considering the different paper finishes may have some part in it.
There's certainly a big color shift between the Solux and the OTTLite. I know that the Solux has very little UV and I think the OTTLite would have quite a lot as I understand that tubes for proofing have added UV (or perhaps it's that standard consumer-grade lights have UV filtered out). The browns are particularly noticeable, but all colors are bluer under the OTTLite. As both are supposed to be around 5000K it has to be down to UV and possibly the spikes in the OTTLite.
I'm beginning to think it may be quite important to target the illuminant when making a profile; perhaps more so than the OBAs. The question is whether the illumination compensation is effective or not, which means more testing (on papers with no OBAs to remove that variable) :(.
Robert
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There's certainly a big color shift between the Solux and the OTTLite. I know that the Solux has very little UV and I think the OTTLite would have quite a lot as I understand that tubes for proofing have added UV (or perhaps it's that standard consumer-grade lights have UV filtered out). The browns are particularly noticeable, but all colors are bluer under the OTTLite. As both are supposed to be around 5000K it has to be down to UV and possibly the spikes in the OTTLite.
I'm beginning to think it may be quite important to target the illuminant when making a profile; perhaps more so than the OBAs. The question is whether the illumination compensation is effective or not, which means more testing (on papers with no OBAs to remove that variable) :(.
Robert
Forgot to add that the OTTLite 100 watt HD label is a CFL I bought at Lowe's. Its blue spike is more from the transitional cyan to cerulean blue region rather than closer to the more optically dangerous UV cobalt blue violet spectrum. I included the comparison to the Solux only to show their affect on paper for this topic and to back up the similarities for the lack of color definition of paper white to the Alzo CFL on the Potlatch sampler comparison to overcast daylight.
The poly fiber glove seen as red brown from the Solux and bluish green from the OTTLite is a metameric error by a combination of both the illuminant and how my camera recorded it. A rare piece of reflective fabric which is why I included it in that test comparison. It's similar to what Stefan mentioned about certain paints. Again its hard to distinguish whether it's the limits of the camera or the illuminant as an example of another rare and odd variable with light and color. The color of the glove under sunlight is a yellowish, grayish umber like this...
http://3.bp.blogspot.com/-rgxrh5Czc1I/TXz6hFLYhyI/AAAAAAAAANc/qD1ytI2o5LA/s320/a%2Bumber.gif
The red spectrum from the Solux halogen throws off my camera to record it as more red brown which can't be fixed using HSL adjusts without throwing off other colors in the image. Visually the Solux renders the glove quite accurate to how it appears in direct sunlight.
The OTTLite was easy for the camera to record the glove's color inaccuracy which is how it actually looked visually but not how it looks under sunlight. Just more variables to consider with light, camera and color.
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Forgot to add that the OTTLite 100 watt HD label is a CFL I bought at Lowe's. Its blue spike is more from the transitional cyan to cerulean blue region rather than closer to the more optically dangerous UV cobalt blue violet spectrum. I included the comparison to the Solux only to show their affect on paper for this topic and to back up the similarities for the lack of color definition of paper white to the Alzo CFL on the Potlatch sampler comparison to overcast daylight.
The poly fiber glove seen as red brown from the Solux and bluish green from the OTTLite is a metameric error by a combination of both the illuminant and how my camera recorded it. A rare piece of reflective fabric which is why I included it in that test comparison. It's similar to what Stefan mentioned about certain paints. Again its hard to distinguish whether it's the limits of the camera or the illuminant as an example of another rare and odd variable with light and color. The color of the glove under sunlight is a yellowish, grayish umber like this...
http://3.bp.blogspot.com/-rgxrh5Czc1I/TXz6hFLYhyI/AAAAAAAAANc/qD1ytI2o5LA/s320/a%2Bumber.gif
The red spectrum from the Solux halogen throws off my camera to record it as more red brown which can't be fixed using HSL adjusts without throwing off other colors in the image. Visually the Solux renders the glove quite accurate to how it appears in direct sunlight.
The OTTLite was easy for the camera to record the glove's color inaccuracy which is how it actually looked visually but not how it looks under sunlight. Just more variables to consider with light, camera and color.
Interesting! Could you try again, but this time 'profile' the camera for Lightroom. That should at least to some extent fix the problems I would have thought.
Robert
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Interesting! Could you try again, but this time 'profile' the camera for Lightroom. That should at least to some extent fix the problems I would have thought.
Robert
I'm assuming you're referring to trying again to correct for the Solux/OTTLite glove metamerism. What is different about Lightroom in how it deals with DNG profiles? I don't see the point.
I already built an OTTLite CFL camera profile but did not build one specifically for the Solux. The OTTLite CFL profile didn't fix the issue but I made the profile converting the Raw to DNG CCchart target in ACR PV2003. I apply that same profile in Lightroom and get the same results.
And besides from watching Andrew Rodney's video on building camera profiles whether for use in Lightroom or ACR I saw the same subtle fixes to color that wouldn't have made a dent in fixing metameric color errors shown in the glove.
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I'm assuming you're referring to trying again to correct for the Solux/OTTLite glove metamerism. What is different about Lightroom in how it deals with DNG profiles? I don't see the point.
I already built an OTTLite CFL camera profile but did not build one specifically for the Solux. The OTTLite CFL profile didn't fix the issue but I made the profile converting the Raw to DNG CCchart target in ACR PV2003. I apply that same profile in Lightroom and get the same results.
And besides from watching Andrew Rodney's video on building camera profiles whether for use in Lightroom or ACR I saw the same subtle fixes to color that wouldn't have made a dent in fixing metameric color errors shown in the glove.
OK, I didn't realize you already had built a profile for the OTTLite. The glove's fabric must have some strange stuff in it!
Robert