Luminous Landscape Forum
Raw & Post Processing, Printing => Digital Image Processing => Topic started by: Hening Bettermann on September 19, 2017, 01:58:22 pm
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In a recent thread about screen to print match
http://forum.luminous-landscape.com/index.php?topic=120611.0
the question of simulating paper white was raised. In PhotoLine, which I use for editing, this option can not be chosen in the softproof dialog. On the german help forum, I asked if this option maybe was baked in and could not be de/selected. Here is the answer of one of the developers, my translation: (for those speaking German, the original thread is here: http://www.pl32.com/forum3/viewtopic.php??p=42757&sid=4825dfe9062dc5920d147aba4da8867a#p42757)
"Since I don't know what 'Simulate paper white' does, I cannot answer this. I can only tell you what PhotoLine does when softproofing (under Mac OS). 3 profiles are involved:
-the image profile (with its rendering intent)
-the profile for the device to be simulated [here: the paper profile of my print service]
-the profile of the output device (screen or printer) [here: my screen].
In the first step, conversion is performed from the image color space into the color space of the device to be simulated, using the chosen option for black point compensation and rendering intent.
In the second step, the conversion is done from the color space of the simulated device to the color space of the output device, without blackpoint compensation. If the output device is the screen, relative colorimetric is used as the rendering intent; other wise absolute colorimetric."
Question:
Does this procedure take paper white into account? And if not, what does the Photoshop option do?
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No experience Photoline but in PS and LR yes turning on simulate paper does exactly that and attempts to display an image to represent what you will see in the final print
Your ICC paper profile will contain a White Point Tag.
Turning this on the application simulates the papers white point as close as possible on screen. Turning it off you will see the white point of your monitor under current conditions which will not be representative of paper white
Attachment shows the effect of switching the simulation on or off
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What the profiles are doing in terms of a soft proof:
•Simulate Paper Colorand Simulate Black InkOff: This produces the
relative colorimetric intent with Black Point Compensation.
•Simulate Black Ink: This produces the relative colorimetric intent
without Black Point Compensation.
•Simulate Paper Color: This produces the absolute colorimetric intent
(no Black Point Compensation).
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Turning this on the application simulates the papers white point as close as possible on screen. Turning it off you will see the white point of your monitor under current conditions which will not be representative of paper white
I always had this thought: Why is the paper (non)white not taken care of in the profile itself. Doesn't the profile know what (255,255,255) is printed as and should it not be reflected when you do the soft proofing? Why do other colors change when the "paper simulation" is turned on. They too are the part of the profile, no?
I am sure there is a simple answer...
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I always had this thought: Why is the paper (non)white not taken care of in the profile itself. Doesn't the profile know what (255,255,255) is printed as and should it not be reflected when you do the soft proofing? Why do other colors change when the "paper simulation" is turned on. They too are the part of the profile, no?
I am sure there is a simple answer...
The paper white is described in the profile itself otherwise soft proof will not work as well as hoped for. You should see the paper white change in soft proofing to reflect the visual appearance of the actual print media. This is also the case with other colours, the change reflecting the print medias ability to reproduce colour which can be massively different to viewing on your monitor without soft proofing initiated.
Click on the image posted and wait a few seconds to see the change to simulation on and off.
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Thank you all for your answers.
Maybe I need to expand my question:
-Is the PhotoLine procedure a "full fledged" softproof including the paper color? Tim Lookingbill questioned this, but it seems to be if I understand you right.
-Which implications has it, that Photoline allows a choice of black point compensation for the first step, but not for the second? I think to avoid that the black point compensation is used twice?
-And which implications has it, that in the second step, rel col is used for the screen, but absolute colorimetric for printers?
It looks to me like Photoshop/Lightroom offer these options to be chosen independent of each other, leaving it to the user to know and select the right one for the purpose; while PhotoLine has certain combinations baked ind and excludes others.
Please help me to look through this. Ultimately, I would like to be able to describe what both programs to in a common terminology. Eg: is the Photoline procedure the equivalent of PS with paper simulation?
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The paper white is described in the profile itself otherwise soft proof will not work as well as hoped for. You should see the paper white change in soft proofing to reflect the visual appearance of the actual print media. This is also the case with other colours, the change reflecting the print medias ability to reproduce colour which can be massively different to viewing on your monitor without soft proofing initiated.
Click on the image posted and wait a few seconds to see the change to simulation on and off.
Tony, Hi:
I understand the paper white is incorporated in the profile. I do see the difference in your illustration. But what I was trying to ask was why does one have to invoke specifically the "paper white and ink" in order to use this info. Why is it not in the part of profile that maps the input-to-output data so it is reflected when you select the profile and rendering intent in "customize Proof Condition" in Photoshop. If I am making my profile, when I make measurements with a spectro/colorimeter, am I not measuring the color which is the result of both the ink AND the paper. How do these two get separated? and why?
:Niranjan.
P.S. I am probably hijacking OP's thread, so I will let it rest now...
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Thank you all for your answers.
Maybe I need to expand my question:
-Is the PhotoLine procedure a "full fledged" softproof including the paper color?
DO you see a difference with it on (you should)? Does it match Photoshop (it should)?
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to nirpat89:
No you are not hijacking at all. The answer to your question
"But what I was trying to ask was why does one have to invoke specifically the "paper white and ink" in order to use this info. Why is it not in the part of profile that maps the input-to-output data so it is reflected when you select the profile and rendering intent"
will most likely contribute to clarification and to making these 2 programs' descriptions of softproofing comparable.
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to Andrew:
Yes I see a difference, but it seems to be about contrast (shadows), not color. As for PS, I don't have it installed, so I can not compare. (and I'm not in the CC).
The print I had produced using the softproof was off in color, too yellow. Maybe this is why?
I have now tried 2 different profiles, the one I actually used (Epson Premium Glossy) and Hahnemühle Photo Rag Baryta. They result in different degrees of contrast change, but not in color. So something is wrong here.
addendum: these 2 profiles are from 2 different print services.
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to Andrew:
Yes I see a difference, but it seems to be about contrast (shadows), not color.
Exactly what one expects.
You see a difference, it's working, and short of a bug in your product, it should match the soft proof using the same settings from the same profile in other ICC aware products that have such soft proofing.
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So it's working. But what about the color? Why is there no difference, and is that why the print is yellow?
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So it's working. But what about the color? Why is there no difference, and is that why the print is yellow?
Paper White! Now that isn't to say the profile is 'correct' (we'd have to do some measurements) or your display white point isn't nailed but the profile predicts a warm paper white.
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Tony, Hi:
I understand the paper white is incorporated in the profile. I do see the difference in your illustration. But what I was trying to ask was why does one have to invoke specifically the "paper white and ink" in order to use this info. Why is it not in the part of profile that maps the input-to-output data so it is reflected when you select the profile and rendering intent in "customize Proof Condition" in Photoshop. If I am making my profile, when I make measurements with a spectro/colorimeter, am I not measuring the color which is the result of both the ink AND the paper. How do these two get separated? and why?
:Niranjan.
P.S. I am probably hijacking OP's thread, so I will let it rest now...
Hi Niranjan
On the face of it it would seem to make sense once in soft proofing mode to automatically switch Paper White and Ink to On and may be not even have the Off option?
TBH I do not know the underlying reasoning for this behaviour - soft proofing has always worked very well for me with simulate paper and ink turned on (so not broken and no attempt made to fix it :D).
Over the years I have seen odd comments that simulate paper and ink does not work correctly or that switching off gives a better result (at least with certain paper types)!
This may indeed be the case for the individual user and if I was to think of a reason or two why this should happen my thoughts would first stray to the validity of monitor calibration and then the quality/accuracy of the ICC profile for a particular paper and viewing/lighting conditions for the print.
Having said that there may be a better explanation of why?
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Biggest issue using show paper white is when you have OBAs present. Most viewing booths aren't compliant with the graphics industry ISO spec. which has enough uV to make M1 the best choice for profiles. The ones most of use use have relatively little uV and M0, the default for most profiles over specs the amount of uV these viewing booths have. I'm not sure about the uV content of Solux but it potentially has a decent amount of uV and so M0 or M1 might work well with it. Andrew Rodney likely has specific info on which M to use with Solux.
The result can be pretty unsatisfactory if there isn't a match with uV and you have OBAs. Show paper color works well with low uV setups with all papers if you use a profile generated with M2 (uV cut).
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Another reason to avoid papers with OBAs.
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But what I was trying to ask was why does one have to invoke specifically the "paper white and ink" in order to use this info.
To get a closer print to display match! To account for the contrast ratio of the print, not the display (per se depending on calibration). To show the effect of paper white on the image IF the profile is doing a good job of doing so (see Doug's point about OBAs etc). Ditto for black.
I keep the simulation option OFF when I decide which rendering intent per image I prefer. I turn it on when I want to see, in FULL SCREEN MODE, the closest preview of what the print should look like, viewed next to the display, then make output specific visual adjustments IF necessary.
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Doug, Andrew good info thanks :D
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Andrew
>Paper White! Now that isn't to say the profile is 'correct' (we'd have to do some measurements) or your display white point isn't nailed but the profile predicts a warm paper white.
TonyW
>This may indeed be the case for the individual user and if I was to think of a reason or two why this should happen my thoughts would first stray to the validity of monitor calibration and then the quality/accuracy of the ICC profile for a particular paper and viewing/lighting conditions for the print.
Hm. How could I know the validity of my monitor calibration? There is an option to validate the profile, using the same software that created it, so how is the validation of this validation? Andrew has earlier called it a 'Feel-good-button'. How can I check the white point of the monitor profile?
Viewing conditions for the print: I have calibrated the monitor to D50 and have established D50 roomlight not Solux but Yuji,
https://store.yujiintl.com/collections/high-cri-led-lights/products/bc-series-a60-high-cri-remote-phosphor-led-bulb-unit-2-pcs?variant=27740384775
even though not enough of it.
The print looks rather yellow/brown, like it had spent to much time in the fixation bath. I'll try to simulate the amount on screen when I'm back home in some days, I'm on the road right now.
The paper in question is Epson Premium Glossy. It does contain OBAs, not sure how much of them.
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Hm. How could I know the validity of my monitor calibration?
It matches the soft proof (with good profiles).
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I keep the simulation option OFF when I decide which rendering intent per image I prefer.
Interesting. Why?
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Interesting. Why?
easier to see.
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easier to see.
Ahhh, apparently yet another instance where I misremembered (and have been slavishly following my faulty recollection of) something I read in Jeff Schewe's book, The Digital Print. The rationale is explained on p. 149 of the paper edition:
With this option selected, instead of using a [relative|perceptual] colorimetric, Lightroom uses an absolute colorimetric that shows the maximum black and the maximum white of your actual paper.
So I gather I should choose the rendering intent first to get the better color match, and only then—in Schewe's delicate phrase—‟make my image look like crap,” and tweak the contrast and clarity adjustments. Is that right?
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So I gather I should choose the rendering intent first to get the better color match, and only then—in Schewe's delicate phrase—‟make my image look like crap,” and tweak the contrast and clarity adjustments. Is that right?
Yes. Without simulation is ideal for picking a rendering intent or editing outside of full screen mode. Then turn it on, that's your most 'accurate' view of what the print should look like, again under the assumption the preview table in the profile is good and sync's up with the output table.
And IF you turn your head away for the display when invoking the simulation, give your visual system a second to update, then look back, it doesn't look as much like crap as Jeff reports when watching the simulation update on screen. LR does a better job here in this respect! Dark bkgnd, gradual change of the simulation and those cool output specific edits applied to a virtual copy!
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Dark bkgnd, gradual change of the simulation and those cool output specific edits applied to a virtual copy!
Got it! Thanks.
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>>How could I know the validity of my monitor calibration?
Andrew:
> It matches the soft proof.
I don't understand. My monitor matches the soft proof in the sense that the 2 or 3 papers I have compared so far look all the same in color, just differ in contrast. Nowhere do I see a color change anywhere near the one that TonyW has demonstrated. That would mean my monitor calibration is close to perfect? And Tony's is not? ??
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>>How could I know the validity of my monitor calibration?
Andrew:
> It matches the soft proof.
I don't understand. My monitor matches the soft proof in the sense that the 2 or 3 papers I have compared so far look all the same in color, just differ in contrast. Nowhere do I see a color change anywhere near the one that TonyW has demonstrated. That would mean my monitor calibration is close to perfect? And Tony's is not? ??
Perhaps, without seeing both setups, it's just speculation at this point. AND contrast SHOULD also match to each paper, so many need multiple calibrations and profiles for each paper! Which is why something like a SpectraView is so nice. It allows you do update multiple calibrations and profiles on the fly based on what you're soft proofing.
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This is what I did back when I was first learning about printer profiles, monitor profiles and such.
Since ICC profiles are made to a D50 Illuminant, I profiled my monitor to D50. And for convenience in comparing colors, I set the monitor white point to 100 Nits (cd/m^2). Then, when reading the emissive color with an I1 Pro spectro, one should get a good match between the LAB color in Photoshop with the picker info tool and the spectro reading. This setup makes it easy to measure, not just "see," what happens when you soft proof.
When I put a white (255,255,255) patch on the monitor and measure it with a spectro I get pretty close to LAB 100,0,0. Then, if I select show paper white the luminance drops and the LAB reading drops as well to the paper white described in the paper profile.
If one has a "perfect" printer paper that reflects 100% of the light, and is therefore neutral by definition, then the LAB reflectance reading would be 100,0,0. Show paper white would result in no change at all! No paper does this though some PTFE based proofing papers come close. Most papers like Epson Ultra Premium Glossy (similar to Costco's) are about 85% reflective with a lot of OBA and is LAB 95,1,-9 (M0) The closest I have to a "perfect" paper is a Baryta paper that is LAB 97,0,0 (M0) which is about 91% reflective. The Baryta paper shows less brightness reduction with "show paper white" and, of course, physically looks brighter next to the Costco.
OBAs are another factor. In the case of the OBA laden Costco glossy, using a profile made with M0 (uV but about 30% less than what true D50 contains) the LAB value measured on the screen drops to 95,1,-9. If I just read the reflectance LAB value directly off the paper then I also get LAB 95,1,-9. That's a pretty significant blue shift.
But, I don't actually see that kind of blue shift when comparing Baryta with Costco Glossy. Unless I take the papers outside and view them in daylight. Then I get the blue shift seen when selecting "show paper white" with the Costco but no blue shift with the Baryta. They look vastly different. The reason is simple. My proofing setup currently uses a good quality LED illuminant and has no significant uV. For that reason I make profiles using M2 (uV cut) unless making prints for displaying outside.
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>>How could I know the validity of my monitor calibration?
Andrew:
> It matches the soft proof.
I don't understand. My monitor matches the soft proof in the sense that the 2 or 3 papers I have compared so far look all the same in color, just differ in contrast. Nowhere do I see a color change anywhere near the one that TonyW has demonstrated. That would mean my monitor calibration is close to perfect? And Tony's is not? ??
The change TonyW demonstrated is quite typical of what one sees with high OBA content paper. However, most people, including me, do not have hard proofing stations, or even normal room light, with significant levels of uV so we don't see the amount of change on the physical prints that "show paper white" produces. But you will see that kind of shift with higher levels of uV. A good way to see for yourself is just bring two sheets of blank paper, one with high OBAs the other without, outside. You will see exactly that kind of blue shift on the OBA paper.
Since I don't usually have prints illuminated with significant uV, even on my hard proof setup, I use profiles made with M2 (uV cut) and avoid OBA paper on critical prints.
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The ICC profile I chose was for a Canon TS8000 series (glossy type) an entry level A4 inkjet that I use for everyday printing duties. This was not the worst looking simulation but just one to show enough difference after being squashed into a Gif.
As I think you are going to an outside source for printing perhaps this example may be of interest. This time using the Master and Proof preview which somewhat lessens the shock looking side by side?
This time with a profile provided by a lab I have used on occassion for a Fuji Frontier glossy paper. I decided I liked the Perceptual rendering best and with a small tweak or two (contrast and saturation green/yellow) should print nicely using this lab service.
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Thank you for your contributions. I will study them more closely when I'm back home in some days.
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So now I'm back home with my calibrated monitor.
Andrew,
I still don't understand in which way the soft proof should match the monitor profile. Everything I see is displayed through the monitor profile, right? Now, in PhotoLine, I switch the softproof on. Now PL chooses the paper profile. The image changes in the exspected way, it becomes less contrasty. I had exspected it also would change in color. You say BOTH the contrast and color should match the monitor profile. Then there would be no change, the master would be the same as the softproof, meaning the soft proof was moot?? Please enlighten me...
Doug Gray and TonyW:
My take away from your posts is that I have to choose a paper without OBAs, otherwise the soft proof is useless for me.
Thank you all for your contributions!
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So now I'm back home with my calibrated monitor.
Andrew,
I still don't understand in which way the soft proof should match the monitor profile. Everything I see is displayed through the monitor profile, right?
Depends on the soft proof settings of course. I explained what RI is used depending on the selection. You can decide to see a paper white or ink black simulation depending on the settings.
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At the risk of reanimating this discussion, my own experience is that I get a better print to screen match if I do NOT select simulate paper white in LR when soft proofing. The loss of contrast on the actual print as compared to the screen simulation is never as dramatic. I have never really understood why and the discussion above particularly wrt OBA's leaves me even more confused.
My situation... I use EPSON premium lustre or EFP which both have OBAs. I soft proof ( and print) using the generic EPSON profiles. I do not use a viewing booth. I use à Solux 4700k lamp (which I understand is really calibrated to simulate the D50 standard) and my monitor is calibrated to a D50 white point. I work in a darkened room and I am careful to ensure that the lamp does not spill onto the screen ( I use a lens hood on a NEC monitor using SpectraView).
Given that the Solux has a very low UV intensity and is presumably not exiting the OBAs, I would have thought their presence would have very little difference on the white point simulation? Or am I to assume that the printer profile in fact assumes that it is being observed in daylight with UV?
BTW, I recently tried checking simulate paper white with EPSON radiant white watercolour paper. In this case the soft proof IS a better match.
Thoughts anyone?
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At the risk of reanimating this discussion, my own experience is that I get a better print to screen match if I do NOT select simulate paper white in LR when soft proofing.
Thoughts anyone?
Simulate has more to do with more than just OBA's! It's about the color of the white and it's 'density' compared to the white of the display. Same with black (it's not a black hole where the display attempts to emit as little as possible). It's about the contrast ratio of the two! You've got a print with maybe a 300:1 contrast ratio on a display that may have a ratio of 1000:1. Now maybe you're calibrating with software that allows control over black and thus the display contrast ratio but not everyone does. All of this works or fails depending on the quality of the profile tables as well; they have two. One for soft proofing, one for output. They should be in sync so to speak. Not all ICC profiles are created equally.
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Simulate has more to do with more than just OBA's!
I realize that. However I was under the impression that there was a suggestion that you agreed with (see Doug's input from sept 20 above and your response and the discussion of UV light) that OBAs somehow limited the accuracy of the simulation. That is the part I do not understand.
BTW why do you refer to two profiles? Isn't the paper/ink profile used for both the soft proof (of the paper) and the output (on the paper)?
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I realize that. However I was under the impression that there was a suggestion that you agreed with (see Doug's input from sept 20 above and your response and the discussion of UV light) that OBAs somehow limited the accuracy of the simulation. That is the part I do not understand.
BTW why do you refer to two profiles? Isn't the paper/ink profile used for both the soft proof (of the paper) and the output (on the paper)?
There are a number of problems associated with soft proofing papers with high OBA content. The prepress industry has standardized on D50 levels of uV but viewing stations with the required uV level are not cheap and it requires that profiles be made using M1, which produces spectral values that include the fluorescent component from D50 uV levels.
Most photographers use profiles made with M0, which, in my experience, has about 2/3s the uV of M1. And current viewing booths very often have even lower uV levels, sometimes almost no uV. Soft proofing with M0 profiles and high OBA paper will produce a significant tint shift. One effective way to handle this is to have different monitor white points, chromaticity and luminance, that are adjusted to make viewing booth paper white have the same apparent luminance and "white." Then, not selecting show paper white but selecting show paper blacks gives the best results. This is most easily done when your setup lets you switch monitor colorspace settings for whatever paper you are using. It makes M0 profiles work well without controlled viewing booth uV. I believe this is what Andrew does in his videos. It's probably the best solution for photographers
However, if your viewing booth is compliant with prepress ISO viewing booth standards (2009 version, IIRC) and you use M1 profiles then the best results are using show paper white. Then the changes in tint as well as luminance (the amount white paper actually reflects) will match closely without switching monitor settings.
The approach I use for critical color work is to simply avoid OBA papers. When you do that then show paper white works great (look away when you do it because you have adapted to a higher luminance). And this works with downloaded profiles or ones made where you are limited to M0.
If OBAs are unavoidable and your prints will be displayed in a place you have access to and has consist lighting but unknown uV content then XRite's OBC approach is excellent. You compare neutral printed patches with spectrally neutral references under the lighting used for print display to create a special profile used for printing.
All of which is why I avoid high OBA papers for critical work.
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I realize that. However I was under the impression that there was a suggestion that you agreed with (see Doug's input from sept 20 above and your response and the discussion of UV light) that OBAs somehow limited the accuracy of the simulation. That is the part I do not understand.
BTW why do you refer to two profiles? Isn't the paper/ink profile used for both the soft proof (of the paper) and the output (on the paper)?
OBA's produce a number of issues with and without soft proofing and much depends on the illuminant, the OBA content etc. It's just a factor that is uncontrollable.
OBA's are just bad news!
http://digitaldog.net/files/24TroubleWithFWAs.pdf (http://digitaldog.net/files/24TroubleWithFWAs.pdf)
Why do I prefer what two profiles? One profile has two tables; one affecting the actual converted values, the other the soft proof. They can be out of sync or just not "accurate' (they don't provide a good output or simulation or both).
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Thanks Doug and Andrew for educating me about OBAs. I admit I had no idea what M0 and M1 are about but this post http://fieryforums.efi.com/showthread.php/5449-M0-M1-M2-measurement gave me a pretty good idea. I understand that OBAs are bad news and the accuracy of the soft proof depends a lot on the profile etc
But at the risk of flogging a dead horse, I come back to my original point. I have no idea if my profile for EFP, which I downloaded from the Pixel Genius site was calibrated with M0 or M1 (maybe Andrew knows), but I do know that with my Solux lamp I do not see (perhaps I am not looking hard enough) any significant color shift, blue or otherwise on the print as compared to the soft proof: I just see an exagerated reduction in contrast when simulating paper white in the soft proof. On the other hand the soft proof without simulating paper white is really quite good, both for color and contrast. So is this just serendipitous.. or is there some technical reason?
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BTW why do you refer to two profiles? Isn't the paper/ink profile used for both the soft proof (of the paper) and the output (on the paper)?
I realized neither Andrew or I answered this question.
Andrew wasn't talking about two profiles, but the two tables in a profile, one of which is used for rendering color to the printer, the other takes the RGB values from that rendering to generate the actual colors printed. For instance printing white (Lab=(100,0,0)) results in no ink but the second profile table can determine the actual color of paper white which is often something like Lab=(95,-2,-1) or so which is a dimmer, and slightly more bluish color. When you select show paper white, the (95,-2,-1) values are what gets sent to your monitor after conversion to whatever monitor colorspace you have. When you don't, the values are scaled to paper white and the "proof" return values will be (100,0,0) or monitor white. That's why you see the drop in luminance selecting show paper white.
Unless you have a hard proof viewing station right next to your monitor with the luminance set so that a perfect paper white has the same brightness and chromaticity as the monitor you are better off not selecting show paper white. And this is without the confounding factors of OBAs which just makes life even more interesting.
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Andrew wasn't talking about two profiles, but the two tables in a profile, one of which is used for rendering color to the printer, the other takes the RGB values from that rendering to generate the actual colors printed.
I was talking about one table that is for printing, one for soft proofing. Two tables, one profile.
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I was talking about one table that is for printing, one for soft proofing. Two tables, one profile.
At the risk of going further into geeky detail, in a profile there are normally 3 tables for printing, one each for Perceptual, Relative, and Saturation Intents. These are called BtoA tables. The inverse Relative table, a AtoB table, is used for creating soft proofs or hard proofs when cross rendering (simulating a print on a different device). It's purpose is to report back, within the limits of interpolation and measurement error, the color printed from whichever one of the printing intents were selected. The Relative Intent table is shared with Absolute Intent in both directions though V4 profiles allow for a separate table. I've not run across a profile that has one.
http://www.color.org/specification/ICC1v43_2010-12.pdf
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At the risk of going further into geeky detail, in a profile there are normally 3 tables for printing, one each for Perceptual, Relative, and Saturation Intents.
Indeed yes, but those are lumped into the 'output' table I referring to. And for soft proofing, there would be the same set of tables depending on the profile structure of course.
Your text about my text seemed to aim only towards output at least as I read it:
but the two tables in a profile, one of which is used for rendering color to the printer, the other takes the RGB values from that rendering to generate the actual colors printed.
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Indeed yes, but those are lumped into the 'output' table I referring to. And for soft proofing, there would be the same set of tables depending on the profile structure of course.
Your text about my text seemed to aim only towards output at least as I read it:
Good point. I skipped the step where the rgb values sent to the device driver are converted back to Lab (the PCS), an intermediate point which is then processed by the monitor's profile to produce the proof display. It is worth it to take time to go through what happens behind the scenes and it does help for folks to understand just how difficult it is to soft proof when OBAs are present. Heck, it isn't even that easy without OBAs complicating things but it is doable and it is worth it.
Andrew, your videos are really excellent vehicles for people just wading into color management. They include the necessary background and detail without anything but the necessary tech speak. The resources at color.org are also excellent but can be intimidating for many. They are great for those that want to delve into the gory details later.
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I still don't understand in which way the soft proof should match the monitor profile.
One philosophy is that the monitor gets calibrated to a Brightness and a White point that visually matches the final output i.e. the print.
There were some earlier discussions and different opinions, if this matching and the comparison screen/print should be done under Soft-proof with or without Simulate paper color.
In any case it requires to be consistent then, when soft-proofing in practice.
Gruß, Peter
Simulate Paper Color:
https://creativepro.com/out-of-gamut-photoshop-previsualization-and-print-prediction/
http://www.cambridgeincolour.com/tutorials/soft-proofing.htm
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Thank you Peter for these 2 very useful links!
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One philosophy is that the monitor gets calibrated to a Brightness and a White point that visually matches the final output i.e. the print.
There were some earlier discussions and different opinions, if this matching and the comparison screen/print should be done under Soft-proof with or without Simulate paper color.
Exactly!
With simulation.
One experts opinion about cambridgeincolor.com:
https://www.dpreview.com/forums/post/60217235
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Exactly!
With simulation.
One experts opinion about cambridgeincolor.com:
https://www.dpreview.com/forums/post/60217235
I wonder how many people reading that link realize the image they incorrectly tout as the "Profile Connection Space" is actually the human gamut CIEuv chromaticity graph? Might as well have a cat picture.
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I wonder how many people reading that link realize the image they incorrectly tout as the "Profile Connection Space" is actually the human gamut CIEuv chromaticity graph? Might as well have a cat picture.
ROTFL!
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One philosophy is that the monitor gets calibrated to a Brightness and a White point that visually matches the final output i.e. the print.
There were some earlier discussions and different opinions, if this matching and the comparison screen/print should be done under Soft-proof with or without Simulate paper color.
In any case it requires to be consistent then, when soft-proofing in practice.
Exactly!
With simulation.
with or without Simulate paper color:
http://forum.luminous-landscape.com/index.php?topic=46010.msg385595#msg385595
http://forum.luminous-landscape.com/index.php?topic=47185.0
The general problem lies in the RelCol-mapping of the source white onto the target white. To assume a 100% Chromatic adaptation to the target white (RelCol WP mapping) might be as wrong as to assume zero Chromatic adaptation to the target white (AbsCol WP mapping). In reality, there is adaptation, but it is not complete (see pdf, chapter 5) (http://docs-hoffmann.de/cmsicc08102003.pdf).
The solution to visually adjust the monitors calibrated white seems to me somewhat ironic/paradox, considering all the science & geek stuff which comes along with Color management.
Peter
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with or without Simulate paper color:
http://forum.luminous-landscape.com/index.php?topic=46010.msg385595#msg385595
http://forum.luminous-landscape.com/index.php?topic=47185.0
The general problem lies in the RelCol-mapping of the source white onto the target white. To assume a 100% Chromatic adaptation to the target white (RelCol WP mapping) might be as wrong as to assume zero Chromatic adaptation to the target white (AbsCol WP mapping). In reality, there is adaptation, but it is not complete (see pdf, chapter 5) (http://docs-hoffmann.de/cmsicc08102003.pdf).
The solution to visually adjust the monitors calibrated white seems to me somewhat ironic/paradox, considering all the science & geek stuff which comes along with Color management.
Peter
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Adaptation is an incredibly complex topic and one I avoid. I run my monitor at D50 and I use ProPhoto which has RGB coordinates at D50 unlike most, but not all, other standard RGB spaces. There are other issues as well including surround variation between the monitor and print viewing station. There are ways to mitigate and minimize those differences but that's only part of the problem.
The larger problem I have is the difference between 2 degree and 10 degree CIEXYZ with my two Eizo monitors. Both are wide gamut but one has a CFL backlight, the other an LED backlight. The peaks of the blues for the two monitors differ by almost 20nm. And, as luck would have it, that has a big impact on the shift in white points between wide area (10 degree) and spot colors (2 degree). Thus, if I profile both for the same white point CIExy (2 degrees) which is the standard, the screen whites, which are wide area, have different tints. The LED Eizo has the least shift based on its spectrum and the CIE 10/2 responses and that's the one I use for proofing. I adjusted the white point on the CFL Eizo away from D50 such that the wide angle white matches the LED Eizo. I don't use that one for color work but at least I can set its white point so that it matches visually and isn't a distraction.
Another issue is the variation human to human in color response. This is an issue with monitors generally compared to prints. Some research indicates humans can be upwards of 10 dE from one person to another and there really is no way for any one person to evaluate how close their color perception is to the CIE's Standard Observer.
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Round up:
In this thread as well as in an earlier one
http://forum.luminous-landscape.com/index.php?topic=120611.0
I asked because I had problems with a print. The highlights seemed dull, and I learned that I had to apply more light for viewing. The print also seemed over all yellowish, and I suspected problems with my soft proofing and OBAs, or thought the failure was on the side of the print service. All wrong! Ernst Dinkla (pigment-print.com) made some proofs for me, and it turned out that both his and those from my first print service (digitaloriginal.de) were perfect in both contrast and color - if viewed under a sufficient amount of light!
And my question why the soft proof showed a difference in contrast, but not in color, may have a very simple answer: The colors of my image were all inside the paper gamut! (The image contains no deep blues or purples).
Thanks again to all who chimed in!
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Andrew
>Paper White! Now that isn't to say the profile is 'correct' (we'd have to do some measurements) or your display white point isn't nailed but the profile predicts a warm paper white.
TonyW
>This may indeed be the case for the individual user and if I was to think of a reason or two why this should happen my thoughts would first stray to the validity of monitor calibration and then the quality/accuracy of the ICC profile for a particular paper and viewing/lighting conditions for the print.
Hm. How could I know the validity of my monitor calibration? There is an option to validate the profile, using the same software that created it, so how is the validation of this validation? Andrew has earlier called it a 'Feel-good-button'. How can I check the white point of the monitor profile?
Viewing conditions for the print: I have calibrated the monitor to D50 and have established D50 roomlight not Solux but Yuji,
https://store.yujiintl.com/collections/high-cri-led-lights/products/bc-series-a60-high-cri-remote-phosphor-led-bulb-unit-2-pcs?variant=27740384775
even though not enough of it.
The print looks rather yellow/brown, like it had spent to much time in the fixation bath. I'll try to simulate the amount on screen when I'm back home in some days, I'm on the road right now.
The paper in question is Epson Premium Glossy. It does contain OBAs, not sure how much of them.
I have some Epson Prem. Glossy. It doesn't have OBAs on the print surface but the substrate is fairly fluorescent. The paper I have is just barely bluish w/o uV, Lab=95,-1,-1 (M2) and only slightly more, Lab=95,0,-3, with D50 (M1).
Not sure what you mean by prints being yellowish. Does the unprinted paper appear yellowish? One way to compare to a good white is to get a roll of plumber's PTFE tape. It's very cheap stuff and really thin designed to seal pipe threads but has a matte surface and but reflects light evenly and is spectrally flat. Lay a piece of across unprinted paper to see what kind of tint a paper has.
You can rough check the paper's profile for this sort of "tint" by printing a colorchecker (download from babelcolor) using Absolute Colorimetric intent. The print should match a colorchecker quite well when viewed in daylight. If not, you have a profile/printer/paper or settings mismatch.
As for "show paper white" the paper is fairly neutral with only a small amount of fluorescence but with a very slight blue shift. So you should also see a very slight blue shift with "show paper white." However, you will most likely notice the much larger luminance decrease because the L*=95 is a significant drop from pure white.
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Hello Doug Gray
> Not sure what you mean by prints being yellowish. Does the unprinted paper appear yellowish?
No, it was not the unprinted paper white (which was not visible anywhere in the image). The print as a whole looked yellowish/brown, in particular visible in the greens (of which the image has a lot). Ernst Dinkla has written to me that "The Kruithof curve learns us that humans have a preference for warmer light when the light level drops. All to do with cons and rods in the eye." So this is the reason - in a sufficient amount of light the print looks perfect. Nothing wrong with print service, paper, profiles or soft proof.
Thanks again!