Softproofing in an OBA world

[howardm]

How should we be dealing with paper profiles for papers that have OBA's (which is something like 90% of them) ?

By my thinking, if the paper was profiled w/ a spectrophotometer that had a UV Cut filter, then the paper white isn't going to be right so using 'Simulate Paper White' is really going to throw the softproof off.  If that is true, then it would seem to be very important to know how the profile was made WRT UV Cut.  And it's somehow unsettling to turn that checkbox off.

Or again, does it boil down to AndrewR's 'whatever setting causes the best match' mantra?

[digitaldog]

The entire UV Cut to Not is open to serious debate, one of the reasons I prefer to measure both ways with the iSis and just test both profiles. The right answer is usually what appears best I'm afraid to say. I've seen cases where the right answer is to cut, and cases where the right answer is don't cut. And differing software products and Spectrophotometer's can change the equation such that, you really need to test both options if you can.

[PhilipCummins]

By my thinking, if the paper was profiled w/ a spectrophotometer that had a UV Cut filter, then the paper white isn't going to be right so using 'Simulate Paper White' is really going to throw the softproof off.  If that is true, then it would seem to be very important to know how the profile was made WRT UV Cut.  And it's somehow unsettling to turn that checkbox off.

I've been a bit curious myself on this matter since there seems to be religions about UV-cut vs UV-uncut. It seems the best method is to record both UV and non-UV with a known amount of UV content that you can use to estimate the effects of UV on a particular media (say, with an i1 Isis). Graeme Gill (of Argyll) claims capturing with UV is better as you can simulate a UV-cut without too much difficulty, but IMHO the lack of accurate measuring systems for UV means that it's still pretty tough to get a handle on. For example if one can measure a light source with UV content + how the media responds this could enable better profiles to be made to estimate how it would react in different situations (ie, daylight vs UV-less LED lights).

[Tim Lookingbill]

So are OBA's being seen by the eye's or the spectrophotometer or both?

What light source is being used to view the OBA's embedded in the paper?

Is the light source the same used in the spectro? I doubt it. And no one's yet provided any hard evidence what light source is used or what that light looks like to the eyes or how it sees OBA's in any surface. There's quite a number of different hues of blue to blue violet with varying amounts of magenta and cyan that can cause weird adaptation errors making printed pastel warm beige colors close to white look slightly greenish if you stare at it long enough.

Under a 4700K Solux lamp all kinds of spectral reflectance characteristics can be seen in a number of "white-ish" surfaces with colors ranging from violet-(regular laser copier paper) to a pastel desaturated navy blue-(the hue of white on my 6000K calibrated display and Epson Ultra Premium Glossy paper) to pastel yellowish green off white-(my Time Warner cable bill) to ashen yellowish beige-(white painted walls).

These spectral sensitivities seen in different substrates aren't so pronounced viewing under neutral-ish fluorescent lights or 2800K incandescent. So which color of white paper is it going to be since it's going to be changing depending on whether it's viewed under a Solux or any other given light?

Why would anyone want to try to correct for this in an ICC profile? It just seems like a lot of nit picking. You all do realize most people viewing prints in a gallery maybe glance at it for about 30 seconds and move on to the next before any of these color subtleties are noticed.

Can someone actually take a photo of a print where OBA's are intolerable to look at in a print and post it here?

[digitaldog]

Just moments ago, built a profile for Luster which has a decent amount of OBAs with and without filter on the iSis, created a profile for each, output each, setup soft proof side by side. Soft proof match prints quite well, output with Cut is preferable by the client I'm with, its a tad warmer appearing (which makes sense). Again, measure both ways, built, view. Pick what you prefer. In this case, the differences in the two sets of measurements are small, and the differences visually are small (again, Cut was visually preferable):

dE Report

Number of Samples: 1748

Delta-E Formula dE2000

Overall - (1748 colors)
--------------------------------------------------
Average dE:   0.12
    Max dE:   0.82
    Min dE:   0.00
 StdDev dE:   0.12

Best 90% - (1572 colors)
--------------------------------------------------
Average dE:   0.09
    Max dE:   0.27
    Min dE:   0.00
 StdDev dE:   0.06

Worst 10% - (176 colors)
--------------------------------------------------
Average dE:   0.40
    Max dE:   0.82
    Min dE:   0.28
 StdDev dE:   0.11

--------------------------------------------------

[digitaldog]

FWIW, Enhanced Matt is SIGNIFICANTLY different in terms of the OBAs with and without cut:


--------------------------------------------------

dE Report

Number of Samples: 1748

Delta-E Formula dE2000

Overall - (1748 colors)
--------------------------------------------------
Average dE:   1.26
    Max dE:   6.46
    Min dE:   0.00
 StdDev dE:   1.14

Best 90% - (1572 colors)
--------------------------------------------------
Average dE:   0.97
    Max dE:   2.69
    Min dE:   0.00
 StdDev dE:   0.69

Worst 10% - (176 colors)
--------------------------------------------------
Average dE:   3.86
    Max dE:   6.46
    Min dE:   2.71
 StdDev dE:   1.12

--------------------------------------------------


Worst patches are paper white (255/255/255). Without cut, we are talking a bStar of -4.22!

[Tim Lookingbill]

Without cut, we are talking a bStar of -4.22!

Wonder what that looks like?

Since it's been indicated in the past and online measuring devices vary between brands and within the same model where each will come up with their own numbers of deviation, I don't see how numbers matter given the visual differences are small.

How do you control this? Why would you want to spend the time and energy to control this?

[digitaldog]

Since it's been indicated in the past and online measuring devices vary between brands and within the same model where each will come up with their own numbers of deviation, I don't see how numbers matter given the visual differences are small.

A minus 4 bStar is significant, and any device worth its salt will show similar such values indicating OBAs. The same model noise (deviation) should be tiny, far less than .05 dE or you got screwed).

[Tim Lookingbill]

Would you say the article linked below shows a good example of the typical effects of OBA's?...

http://www.northlight-images.co.uk/reviews/paper/innova_fibaprint.html

Can it be worse than what's shown there?

[Ernst Dinkla]

Lots of RC papers that have a b -10, the most extreme I have measured is b -10.7.
The b value is an indication only, it doesn't tell enough about the mix of normal whitening agents + paper fiber and fluorescent brighteners and the effect to changing illumination with UV and without UV. A nice example is the Hahnemuhle Baryta FB 350 grams, its paper white is the result of the paper fiber reflectance at the red end and a huge dose of FBA at the blue end, hardly anything in between that contributes to the paper white reflectance. You can expect a huge color inconstancy in changing light. It has a b -8.9. The EEF has at least some whitening agents in between the visible spectrum extremes, though only in the inkjet coating.

The UV-cut measuring devices still deliver "measurements" below where they are actually cut to make profile creation software work. As I understand from an ArgyllCMS forum thread the ColorMunki doesn't measure below 430 Nm and repeats the value measured there down to 380 Nm. Papers without FBA already drop in reflectance over that wavelength range, not to mention FBA loaded papers. I expect it will be somewhat better simulated with an UV-cut Eye1 Pro. I think a lot of the purple/blue sky profile issues may be more related to the measuring devices + paper FBA content than to the profile creation software. A choice of 3 varieties of FBA paper content to simulate could be an option. Remains the problem that you can not predict the display conditions. On the other hand measuring FBA papers with an UV-cut device and expecting that they will not be used in light with UV content is not realistic.

Argyll's simulation of an UV-cut measurement based on a normal spectrometer measurement at least starts from measurements within that part of the spectral range. Sounds better than the other way around. But I think it actually should simulate the paper white reflectance if the FBA was removed from that paper. Which is something else. I think it is possible to estimate what the "measurements" would be in that case, I  have measured a lot of inkjet papers and their paper base and FBA paper qualities are often based on non-FBA paper qualities. Quite obvious where the FBA effect kicks in at the shorter wavelengths and start absorbing UV light at even shorter wavelengths.

The safest route is reduced or no FBA content in the paper and measuring with a normal spectrometer that has no UV-cut. It at least measures into that part of the spectrum, there is still violet-blue reflectance to measure even if there is no FBA effect. It is also the best paper choice when display conditions are not predictable, it will be less influenced on its white reflection by framing behind acryl or glass, it should (in general) keep a more constant white reflectance in time. Aardenburg has a nice page on FBAs and light and framing.
http://www.aardenburg-imaging.com/news.18.html


met vriendelijke groeten, Ernst Dinkla

New: Spectral plots of +250 inkjet papers:
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm

[Shane Webster]

And the OBAs can be significantly negated when framed behind UV glass/acryllic, further complicating the OBC/UVC measuring debate.

[Ernst Dinkla]

And the OBAs are negated when framed behind UV glass/acryllic, further complicating the OBC/UVC measuring debate.

Depending on the glass type though but there will always be some loss of FBA effect. The Aardenburg article gives a good impression of what can happen.
With UV-cut glass etc it will be more pronounced though different versions UV-cut filters exist as well.

In Dutch though:
http://www.scribd.com/doc/27768335/UV-werende-eigenschappen-van-verschillende-typen-glas-kunststof-en-folies-voor-museale-doeleinden


met vriendelijke groeten, Ernst Dinkla




New: Spectral plots of +250 inkjet papers:

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm

[Shane Webster]

Depending on the glass type though but there will always be some loss of FBA effect

Very true.  I should have used more precise language.  I've modified my previous post to state that OBAs can be significantly reduced.  Your comments though point out the increased difficulty in soft-proofing papers that contain OBAs.  Instead of just proofing to a viewing condition that uses a particular illuminant, when using papers that contain OBAs, one is then presented with the added question of whether to also attempt to proof to a particular glass/acrylic that allows a given percent of UV light through to the print surface.  I've made profiles with and without a UV filter and made profiles letting PMP correct for OBAs, printed the same image soft-proofed for each profile and put each behind UV protected acrylic to judge the results.

[Ernst Dinkla]

Your comments though point out the increased difficulty in soft-proofing papers that contain OBAs.  Instead of just proofing to a viewing condition that uses a particular illuminant, when using papers that contain OBAs, one is then presented with the added question of whether to also attempt to proof to a particular glass/acrylic that allows a given percent of UV light through to the print surface.  I've made profiles with and without a UV filter and made profiles letting PMP correct for OBAs, printed the same image soft-proofed for each profile and put each behind UV protected acrylic to judge the results.

Which should moderate the statements on soft proofing in the other threads. It is a nice tool but there are too many different conditions in the actual display of prints to compensate for in the softproof side of a profile and to find an equivalent for in one proof viewing lamp. It is a tool at best already compromised by its transmissive, additive RGB color mixing where it should be at least reflective, subtractive CMYK mixing. Displays already possible BTW.

I had to make fascimiles for already faded prints/drawings of Russian constructivists, 1920's origin and so on post war, post revolutionary Russian paper. Conditions were that the photography had to be done with the originals behind their UV-cut glass and the prints to be made would get another type UV-cut glass in front of them. You try to get pieces of the UV-cut glass types, note the museum light conditions, recreate more or less the conditions in your shop, make a range of proof prints + take with you a Pantone sample book, go back and forth at least 3 times between the two places. Check with 4 eyes. I don't think that is a slower proces and less accurate than trying to make a fitting ICC profile for the conditions and go the softproof route. In that kind of work the monitor is more or less the fifth wheel on the carriage, you better not use it but for visualisation of the edits to be done. The match has to be made between original and copy at the place where they have to match. True, this isn't the usual digital take to print route but if someone writes that he has 100% output in photo prints by softproofing and no paper waste at all then I have my reservations about his judgment on what is the best or optimal print possible. Something you can not discuss. almost a matter of taste.


met vriendelijke groeten, Ernst Dinkla

Try: http://groups.yahoo.com/group/Wide_Inkjet_Printers

[Tim Lookingbill]

So how would you edit an image to compensate for OBA's or whatever color the paper takes on under a targeted light source?

Is there any demonstration online that shows what to edit for like a before and after?

[tho_mas]

So how would you edit an image to compensate for OBA's or whatever color the paper takes on under a targeted light source?

Calibrate your monitor to match paper white (both white point and brightness level under the respective viewing conditions) and simply softproof without simulation of paper color (you might activate the simulation of black ink, though).

[Ernst Dinkla]

So how would you edit an image to compensate for OBA's or whatever color the paper takes on under a targeted light source?

Is there any demonstration online that shows what to edit for like a before and after?

Recreate the light source in your shop as best as you can. Edit for a pleasing/optimal print. Be prepared for the fact that it may not deliver what you would like to see. Another paper may deliver a better print. Of the maybe 80 RC papers I measured 2 that had no FBA. In fine art papers, matte rag, baryta, fiber, the non-FBA percentage may be 30% and the FBA content will be on average somewhat reduced compared to RC papers.

Why not approach it from the other side?  Get a paper that has no FBA but still has a high white reflectance. Use a normal spectrometer that measures into UV. Use an inkset with more color constancy in changing light. In that case your softproofing becomes more reliable for different display conditions and the print will on average look better too in different display conditions. Of course it can be optimised if for example your average display conditions come closer to 4000K than to 5000K etc. The profile creation software then has the appropriate choices, the viewing lights 3200 up to 4700K are available.

While checking the RC papers for non-FBA qualities I hit on Epson Proofing White Semimatte. Googling for it I found one photographer mentioning its use and recommending it on his website. Epson BTW uses it to get that 98% of the Pantone colors covered with the 4900, 7900, 9900. So there is no sacrifice on the gamut with that paper. It is just loaded with normal whitening agents like Canson Rag Photographique and some other qualities also have.
http://www.epson.co.uk/Printers-and-All-In-Ones/Large-Format/Epson-Stylus-Pro-4900/Overview

There are also RC papers with a b -1 or -2, low FBA content and with sufficient normal whitening agents to give a more balanced paper white reflectance. HP has several.


met vriendelijke groeten, Ernst Dinkla



New: Spectral plots of +250 inkjet papers:

http://www.pigment-print.com/spectralplots/spectrumviz_1.ht