Luminous Landscape Forum
Raw & Post Processing, Printing => Printing: Printers, Papers and Inks => Topic started by: unesco on July 24, 2017, 04:19:08 pm
-
I conduct some extensive research on ABW behavior on my P800 and 3880 also making QTR profiles.
One fundamental question comes to my mind - I have read tons of information in the last 2 years about ABW linearization and have not found definitive answer - 21/51 patch set and its profile embedded for test print. Should it be:
1) as is the target e.g. in QTR folder, no profile attached,
2) attached GrayGamma2.2 as ABW assumes it,
3) attached linear gamma profile e.g. QTR GrayLab,
4) attached linear gamma profile e.g. QTR GrayLab and then converted to GrayGamma2.2,
5) any other?
1 and 4 give different results. That should be something obvious but now I am mixed-up and really appreciate valuable answers. In the Internet I have found different approaches. I am asking only about the target file to be printed, not the rest of the process.
-
I don't understand your question. Are you printing the patch set to make a QTR profile? If this is the case you need to print the patch set out with no color management in the same way you would profile a colored inkset. I use the Adobe print utility program to do this and make sure that that your printer driver is correctly configured.
-
How are you printing? Which operating system and which program? If under Windows and from a recent version of Photoshop then there's a problem that we've discussed here before, which is that Photoshop will silently convert all images printed using the printer manages colors setting to sRGB, which is the setting you need to use for ABW. This is tricky to work around. ACPU is one solution, but then you have the same problem again when you print images, and you can't use ACPU for that as its image placement settings are broken under Windows. OS X also has its CM quirks, but at least there is Roy Harrington's Print Tool.
More generally, I'd measure linearity using the same workflow that I'd use to print images. You print your images in gray gamma 2.2? Do the same for the targets. For ABW it shouldn't matter whether the image is unassigned or you assign it to grey gamma 2.2, as ABW ignores the ICC.
-
I Think I understand what Unesco is asking. Researching the web yields contradictory recommendations on how to build and print a 21-step test chart for the purpose of creating linearized ICC profiles with QTR and for Epson printer destination. He wants to know which method (he listed four) is best and more importantly WHY? Perhaps they all work but in different situations? Some say that the test chart to be printed should have no color working space assigned to it. Some say it should have a 2.2 gamma space assigned. And apparently QTR has their very own color space as well. . . Why would that even be necessary?
I have been struggling with this issue myself and can never get a satisfying answer. But let me take a crack at it, and someone can correct me.
Which color working space (e.g., aRGB 2.2, Prophoto 1.8, QTR Gray Lab 1.0, Gray Gamma 2.2, or NONE) that should be assigned to a test chart before it is sent to the printer depends on which color space that test chart was sourced from and intended to have by its author. Just because an image has no color space assigned to it doesn't mean that it has no color space. All images have a color space baked into it even if it has no tag or sign that says: Hello world, my creator made me to be viewed in the sRGB color space! Every pixel must have an RGB or L*a*b* or CMYK number value associated with it. How else would the monitor know which color to display esch pixel with or how to tell one patch on a test chart apart from another patch?
So if a calibration software, such as QTR or Colormunki, provides their own test chart digital negative, they obviously don't want you to go assigning some god-knows-what color space to it. They designed the chart to be used with their software and nobody else's. That's why they usually instruct to print the target with no profile. Some calibration systems, on the other hand, will ask for a 2.2 gamma profile assignment. That's because they designed their linearization program to work with 2.2 gamma test charts.
Am I warm?
-
Warm but not hot.
I will restrict myself to commenting on QTR. It assumes nothing. On Windows it is a stand alone application that is not color managed and whatever color profile is or isn't embedded in the image file will make absolutely no difference to how QTR prints the image. It's up to you to manage the ICC - assign or convert (as per our other thread) - before you save the file and send it to QTRGui. You can send an untagged image, or one where you've assigned any profile you like, to QTRGui and you'll get the same print. The one thing that will make a difference is if you convert to another ICC, because then for an untagged file, Photoshop will assume your default grayscale working space and convert the file, changing it. That's going to change the print, but not because QTR did it, Photoshop is the culprit.
On OS X, QTR is a printer driver and it too is color profile agnostic. It's just a relatively basic printer driver. It doesn't expect anything. The printing software is another matter. Both Photoshop and Print tool offer options to convert to an ICC on the way to QTR. Since OS X 10.6.8 you can't print untagged or gray gamma 2.2 images from Photoshop using QTR without getting a silent profile conversion behind the scenes. This was the precise reason that Roy Harrington created Print Tool - to allow you to do that. Yes, ACPU does as well, but Print Tool is more functional. So to get the same degree of control as in Windows, use Print Tool (or ACPU).
So QTR has no expectations. The question of what ICC to use is really about what workflow and software you are using. Most of the documented workflows assume gray gamma 2.2, so that is how you need to print the target. Your print the target the same way you are going to print images, taking care to avoid any silent profile conversions. If you print in Windows using QTRGui, or in OS X with Print Tool with CM turned off, you can print an unassigned target, or one with gray gamma 2.2 or AdobeRGB (same as gray gamma 2.2 but in RGB space), and it won't matter. My impression is that Roy Harrington supplied his test charts as untagged images because he assumed that people would be printing them that way, in line with generally accpeted workflows, but that's just an impression, and it's about workflow, not software.
My understanding of the ICC profiles that ship with QTR, like gray-lab.icc, is that they were created by Roy Harrington as generic profiles for people to use long before devices like the i1 became widespread and people started creating their own. They're mostly dated around 2005.
All images have a color space baked into it even if it has no tag or sign that says: Hello world, my creator made me to be viewed in the sRGB color space!
Yes and no. An image file is just a bunch of numbers and an ICC profile is a guide to color managed software as to how to interpret it. It's true that if someone sends me an untagged color image then I will want to know what color space they intended, because that will tell me how it is supposed to be viewed. The same is true for a B&W image, but not so for test charts. No-one asks what color space the x-rite test charts are in, for the purposes of creating a color profile. And so it is for QTR under most workflows.
-
Thank you all for your replies! Now, I am on my mobile so only a short answer.
I am on Windows, print patches using PS in the newest version and print using ABW on Epson 17" printers.
I use QTR in another workflow, so now QTR itself is not targeted in this discussion.
textshooter, you've got exactly my idea! That's what I mean and look for.
I will reply in more details when I get access to my PC
-
First, thank you all for such comprehensive replies.
The core of my problem should be defined as follows: "how to generate patch target for linearisation and ABW printing under Windows and PS (or maybe other software as ACPU or QImage)". It only looks as a simple question.
I had some discussions on local forum with a guy who has P10k and would like to make better ABW prints, and after long exchange of comments and print tests/measures on both sides I started to doubt I can answer such a question.
ABW mode on P800 looks very well, sometimes it is hard to distinguish it from QTR prints, so I would like to improve it, but first to understand its settings.
More generally, I'd measure linearity using the same workflow that I'd use to print images. You print your images in gray gamma 2.2? Do the same for the targets.
it only looks so simple - I would print the target that way, but how the target should look like? how to prepare the target? That could be my 1)-5) version of profile assingment/conversion in the first post.
He wants to know which method (he listed four) is best and more importantly WHY? Perhaps they all work but in different situations?
Indeed, I can linearise the printer according to reference, but reference is different in each case.
-
Your print the target the same way you are going to print images, taking care to avoid any silent profile conversions.
it only looks so simple - I would print the target that way, but how the target should look like? how to prepare the target? That could be my 1)-5) version of profile assingment/conversion in the first post.
Indeed, I can linearise the printer according to reference, but reference is different in each case.
Sorry about the long post. As the saying goes, I didn't have time to write you a short one. Probably not today either. When I said to print the target as you would images, that assumed a workflow where you print without any color management. That's one of two possible workflows. The other is to use color management and print images using an ICC, which if I recall correctly is what Alan Goldhammer was recommending. You don't often see the difference between these two alternative workflows discussed and compared. People just assume or or the other. Two different workflows, resulting in slightly different prints and requiring different image editing and different approaches to soft-proofing (see below).
First, thank you all for such comprehensive replies.
The core of my problem should be defined as follows: "how to generate patch target for linearisation and ABW printing under Windows and PS (or maybe other software as ACPU or QImage)". It only looks as a simple question. ... I would print the target that way, but how the target should look like? how to prepare the target? That could be my 1)-5) version of profile assingment/conversion in the first post.
Possibly I'm not thinking straight, but I can't see the problem of patch generation and preparation. If you make a color profile, you have pages of standard patches supplied by x-rite. No generation or preparation. You print them as they are, which is usually untagged, being careful to turn off all color management. You create a profile. You use that profile to print. QTR is no different. It comes with standard 21 and 51 untagged patches, you print one of them without any color management, you create a profile using either the QTR-Create-ICC or QTR-Create-ICC-RGB application, and print using the profile. You do the same if If you want to use QTR profiles with ABW. I can't see the problem.
We've been discussing the other workflow, printing without color management, over in the digital B&W forum:
http://forum.luminous-landscape.com/index.php?topic=118989.0
which as I noted above, will result in slightly different prints and requiring different image editing and different approaches to soft-proofing. But the targets used to create the ICC are printed the same way.
What am I missing? Are we still talking at cross-purposes? In relation to your four options, I consider #1 and #2 to be the same, since you print the targets without any color management enabled and tagged profiles should be ignored.. I haven't seen anyone recommend #3 or #4 for printing the QTR test patches. You got a link? I can't see that #3 would be any different so long as you assigned QTR GrayLab and didn't convert to it. I would not recommend #4, and I don't understand why someone would.
-
I haven't seen anyone recommend #3 or #4 for printing the QTR test patches. You got a link?
Here is a link to a source that advocates #3.
http://cameratico.com/guides/black-and-white-icc-profiles-and-soft-proofing/ (http://cameratico.com/guides/black-and-white-icc-profiles-and-soft-proofing/)
Where I get confused is where the author criticizes the use of gray gamma 2.2 test charts and insists on a 1.0 gamma chart, particularly the QTR GrayLab variety. Didn't you say that it doesn't matter what gamma the chart is encoded with because both the ABW driver and QTR are gamma agnostic? And because the ABW driver converts whatever it receives to sRGB gamma 2.2 anyways. Something tells me I should be worried of "silent profile conversions" but not sure where to look.
-
Sorry about the long post. As the saying goes, I didn't have time to write you a short one. Probably not today either. When I said to print the target as you would images, that assumed a workflow where you print without any color management. That's one of two possible workflows. The other is to use color management and print images using an ICC, which if I recall correctly is what Alan Goldhammer was recommending. You don't often see the difference between these two alternative workflows discussed and compared. People just assume or or the other. Two different workflows, resulting in slightly different prints and requiring different image editing and different approaches to soft-proofing (see below).
I think ABW is color managed under PS on one hand, on the other I do not want to use ICC, because I would like to minimise use of colour inks, especially Y on 3880, and with ColorMunki I cannot (except of Argyll) prepare good, neutral ICC.
Possibly I'm not thinking straight, but I can't see the problem of patch generation and preparation.
[...]
I can't see the problem.
I also have no problem to generate untagged patch file of any size e.g. using Argyll, but should it be untagged? (option #1)
What am I missing? Are we still talking at cross-purposes? In relation to your four options, I consider #1 and #2 to be the same, since you print the targets without any color management enabled and tagged profiles should be ignored.. I haven't seen anyone recommend #3 or #4 for printing the QTR test patches. You got a link? I can't see that #3 would be any different so long as you assigned QTR GrayLab and didn't convert to it. I would not recommend #4, and I don't understand why someone would.
what you mean cross-purposes? there is no hidden agenda here ;-).
#1 and #2 should be the same, but because of another reason than your mentioned (PS do manages colors in this print somehow, since it converts images to sRGB for "Printer manages colors"). sRGB has gamma = 2.2 so the same as natively assumend in my PS setup for B&W.
#4 I have seen somewhere, and also it looks logical. what we want to make L linear so we need to have linear target (GrayLab assingment), but ABW expects GG2.2 so there is conversion to it later (am I saying stupid things?).
what is the most logical here is to prepare smooth gradient under PS in sRGB and then to limit it to 21 or 51 steps. this would require to switch-off PS dithering as well as work on 16 bits first, then to convert it to 8 at the end. what do you think?
-
Here is a link to a source that advocates #3.
http://cameratico.com/guides/black-and-white-icc-profiles-and-soft-proofing/ (http://cameratico.com/guides/black-and-white-icc-profiles-and-soft-proofing/)
That link is just the standard approach to using QTR for generating ABW profiles. Note that this approach can only be used with WinOS as MacOS does not permit it (long thread several years ago here on LuLa when Apple eliminated this approach. Eric Chan stopped making ABW profiles at that time.
-
what is the most logical here is to prepare smooth gradient under PS in sRGB and then to limit it to 21 or 51 steps. this would require to switch-off PS dithering as well as work on 16 bits first, then to convert it to 8 at the end. what do you think?
You have a ColorMunki, correct? The easiest thing is to use Argyll to generate either a 21 or 51 step B/W patch set, print it using the Adobe utility, read the data using Argyll and then use the QTR scripting tool to generate your ABW profile.
-
That link is just the standard approach to using QTR for generating ABW profiles. Note that this approach can only be used with WinOS as MacOS does not permit it (long thread several years ago here on LuLa when Apple eliminated this approach. Eric Chan stopped making ABW profiles at that time.
In what way is using a QTR-generated ICC to print ABW on a Mac using Roy Harrington's Print Tool any different to what Eric Chan's profiles used to allow us to do directly in ABW?
-
This is a preliminary comment on the cameratico article. I don't understand how it could work. It seems to imply that somehow printing a 21 step chart tagged with (assigned to) the 'QTR – Gray Lab' color space via ABW and creating an ICC via QTR should give different results to leaving it untagged or tagging it with gray gamma 2.2. That's not my understanding and experience. I thought that ABW was also ICC agnostic, at least the current version of it. The original draft of the article was from July 26th, 2012 - was ABW ICC aware back then, as Alan pointed out that it used to be?
I've also got a few other uncertainties about that article and some apparent gaps in it. I drafted a long and rambling post, but I think it's better if I find some time to test before I comment further.
-
In what way is using a QTR-generated ICC to print ABW on a Mac using Roy Harrington's Print Tool any different to what Eric Chan's profiles used to allow us to do directly in ABW?
You cannot use ABW profiles on a Mac. Don't ask me why as I have always been on Windows. There is a whole thread on this from a couple of years ago that discussed the matter. Had to do with an Apple decision
-
I thought that ABW was also ICC agnostic, at least the current version of it. The original draft of the article was from July 26th, 2012 - was ABW ICC aware back then, as Alan pointed out that it used to be?
Yes it was. I was using the scripting tool to make ICC profiles once Eric Chan stopped doing so.
-
You cannot use ABW profiles on a Mac. Don't ask me why as I have always been on Windows. There is a whole thread on this from a couple of years ago that discussed the matter. Had to do with an Apple decision
You keep saying this, but I believe you are incorrect. Are you on a Mac? Have you tried to print using Roy Harrington's Print Tool, and enabling the ABW in the software and specifying an ICC profile and printing this way? It's a bit hard to compare empirically now to the Eric Chan option, as that option has gone, but I am fairly certain that this is conceptually the same. Perhaps that old thread pre-dated the arrival of Print Tool. But before you keep repeating that claim, you should check the approach I suggest, because I don't think that your statement is correct.
-
Yes it was. I was using the scripting tool to make ICC profiles once Eric Chan stopped doing so.
What is this scripting tool you speak of? If I got my hands on it, would I be able to make ABW ICC profiles for my Epson 3800 (Windows 7) today? The same profiles Eric Chan provided (link below). The kind of profiles meant for double color management. By that I mean PS Manages Color turned on (with ICC selected) at the same time Printer Manages Color turned on (ABW mode selected).
http://people.csail.mit.edu/ericchan/dp/Epson3800/printworkflow.html (http://people.csail.mit.edu/ericchan/dp/Epson3800/printworkflow.html)
Scroll down to the header title: How to print B&W images with the ABW driver (with ABW profiles)
-
You have a ColorMunki, correct? The easiest thing is to use Argyll to generate either a 21 or 51 step B/W patch set, print it using the Adobe utility, read the data using Argyll and then use the QTR scripting tool to generate your ABW profile.
Thank you for your kind answer.
Yes, I use Color Munki (I do not need anything more for B&W printing right now).
I think, I have pointed out my objectives not clearly enough - again, I DO NOT want to make ICC profile for ABW but would like to research ABW behavior with different settings. thus I need reference patch set.
I know how to generate UNTAGGED 21 or 51 step B/W patch set, I know how to measure it either with color munki software or Argyll, BUT do not know if the untagged version is correct (option #1 from my initial email) or maybe other target setup for patches is needed for PS/ABW print and WHY (PS/ABW is different in print technique and results so I suppose the patch set should be different)?
Is it clear enough now?
BTW, I have measured some of Eric Chan profiles for untaggest patch set under ABW print in PS - they are not linear.
So still now answer how the patch set should look like: options #1-#5...
-
What is this scripting tool you speak of? If I got my hands on it, would I be able to make ABW ICC profiles for my Epson 3800 (Windows 7) today? The same profiles Eric Chan provided (link below). The kind of profiles meant for double color management. By that I mean PS Manages Color turned on (with ICC selected) at the same time Printer Manages Color turned on (ABW mode selected).
http://people.csail.mit.edu/ericchan/dp/Epson3800/printworkflow.html (http://people.csail.mit.edu/ericchan/dp/Epson3800/printworkflow.html)
Scroll down to the header title: How to print B&W images with the ABW driver (with ABW profiles)
http://www.quadtonerip.com/html/QTRiccprofile.html is the tool. IIRC you use the RGB version of the tool to make the profile. Keith Cooper has a description of how to do this here: http://www.northlight-images.co.uk/black-and-white-print-linearisation-with-i1profiler-and-qtr/ these are the same type of profiles that Eric used to make.
-
Work is busy but I've done some testing. My hunch is that the cameratico article was written back in the day when ABW accepted ICCs, and so was a profile aware application. It mattered what ICC you tagged your test patches in. I never used this version of ABW so I've not seen this, and I have no way to access it now to check. But that's my hunch, because the cameratico article workflow tells you to do this, and if I understand his results, then tagging the test chart with the grey lab space seems to have some effect. If you are still using that printer (3800?) and the old driver then it may still work for you. He must have experimented with different ICCs until he found one that in conjunction with the color management engine of ABW created linear results. Again just a hunch.
But that's not the case now. I just followed his workflow as best I could (harder in current versions of Photoshop - see below) and I also printed his test chart tagged with gray gamma 2.2, and measured them. The results were identical. Tagging with different ICCs had no effect.
So all my comments earlier still hold, including about options 1-5 in the original post. Both the latest version of ABW and QTR are ICC agnostic applications and it doesn't matter how you tag your test charts. You just need to ensure that you have color management off to print the test charts for creating an ICC. Also for printing images via ABW if you wish to use the no color management workflow.
Some other observations.
The scripting tool that Alan refers to is just different terminology for the QTR-Create-ICC and QTR-Create-ICC-RGB applications that we've been discussing all through this thread.
Turning off color management in recent Windows of Photoshop is getting harder and harder. In the past we've discussed here on Lula how to avoid the silent sRGB conversion by Photoshop that you'd get under the printer manages color setting on Windows. See for example http://forum.luminous-landscape.com/index.php?topic=103432.0 . It looked to me today like some of these tricks no longer work. Qimage is then your best option.
Those who want to print to ABW on a Mac using and ICC should open their copy of Print Tool, and in the bottom right corner in the 'Print Color Management' section, ensure that 'Epson ABW mode is checked, and then next to it, that 'Print-Tool Managed' is selected in the drop-down list of options, and below that select you profile and rendering intent etc and proceed, and you should have the same functionality as the Chan profiles in the old driver used to provide.
-
I need a drink.
-
Turning off color management in recent Windows of Photoshop is getting harder and harder. In the past we've discussed here on Lula how to avoid the silent sRGB conversion by Photoshop that you'd get under the printer manages color setting on Windows. See for example http://forum.luminous-landscape.com/index.php?topic=103432.0 . It looked to me today like some of these tricks no longer work. Qimage is then your best option.
The null transform trick to print w/o color management continues to work fine in Photoshop under Windows, including the latest Win 10. I make a point of checking it because of its uncertain future.
http://forum.luminous-landscape.com/index.php?topic=117516.msg973997#msg973997
-
Who cares if Photoshop does a silent conversion or not? The ABW driver is going to convert it to sRGB anyways. Unless something screwy happens when an image is converted twice in succession to sRGB?
-
I need a drink.
That was my reaction too, when I read that article and tried to understand and replicate the results. Why doesn't someone try and replicate mine? Just make sure that all color management is off.
The null transform trick to print w/o color management continues to work fine in Photoshop under Windows, including the latest Win 10. I make a point of checking it because of its uncertain future.
http://forum.luminous-landscape.com/index.php?topic=117516.msg973997#msg973997
I'll have to read that exchange between you and MHMG in detail later. Yes the null conversion still works, but my impression is that there are less options than there used to be. The author of the cameratico article suggests setting the printer profile to the QTR-gray-lab monochrome ICC that his test chart is tagged with, but monochrome ICCs don't appear in the list. I'm not sure they ever did, as the printer driver presents to software as an RGB device.
I think what I used to do was convert my gray gamma 2.2 image to AdobeRGB, since it's essentially the same thing, and then set it as the printer profile. But AdobeRGB no longer appears in the list of printer profiles in the printer. Perhaps my memory is faulty, but I thought it was there, along with ProPhotoRGB and sRGB, and without these the null transform is harder to use. Not impossible, but harder. That's what I meant.
Who cares if Photoshop does a silent conversion or not? The ABW driver is going to convert it to sRGB anyways. Unless something screwy happens when an image is converted twice in succession to sRGB?
There are two options here. One is to specify Photoshop Manages Colors in the print dialog. Under this option you specify the printer profile to be the same as the document profile, if you can (see just above). Under this option there's no silent conversion, and neither Photoshop nor ABW will silently convert to sRGB.
The other option is to specify Printer Manages Colors in the print dialog. Under this option, you will get a silent conversion to sRGB. According to some comments by an Adobe software engineer over on TOP last year, this is an intentional design decision by Adobe in relation to Windows, and nothing to do with the Epson driver. I seem to recall is has to do with protecting less expert users, and something to do with likely future changes in the Windows printing pipeline. The workaround for this workflow is to convert from gray gamma 2.2 to AdobeRGB and then assign sRGB. At this point Qimage is looking good.
Need another drink?
(Edited for a typo)
-
I'll have to read that exchange between you and MHMG in detail later. Yes the null conversion still works, but my impression is that there are less options than there used to be. The author of the cameratico article suggests setting the printer profile to the QTR-gray-lab monochrome ICC that his test chart is tagged with, but monochrome ICCs don't appear in the list. I'm not sure they ever did, as the printer driver presents to software as an RGB device.
The null transform works fine with any printer profile. At least in RGB space. Just assign any paper profile. It doesn't have to even be one for a paper you have or even printer you have as long as the profile is installed and a printer driver exists for that printer.
Here's the workflow I use:
For patch target sheets, I just assign an arbitrary printer profile. It doesn't even have to be a profile for the printer you use but can be any RGB profile for any model printer. Then, I select Photoshop manages color and print using ICC disabled with the same printer device settings used for printing color managed images. The settings in Photoshop such as Perceptual, Relative, Absolute, and black point have no affect at all since Photoshop simply assumes that the RGB values, which are already in printer space, Are the same as whatever you select. Otherwise the null transform wouldn't work.
I can't say how this would affect ABW operation. I don't do B&W often but when I do, I have a special patch set with several hundred extra neutral, and near neutral, patches. I only use a profile made from this for B&W (in RGB color mode) though since it can create some odd profile characteristics in more saturated areas. At least with I1Profiler.
An ongoing concern I have with Adobe is that they will either prohibit this outright, or worse, round trip from device space back to Lab PCS then back to device space. So I test this with new updates just in case though I think it unlikely they will start doing it.
I suspect this approach of using a printer profile to effect a null transform would work fine on Apples but I don't have an Apple to test it. Wouldn't surprise me at all if the Apple issue isn't something that only shows up in conventional (matrix) RGB spaces. Perhaps that's why Photoshop has removed most of them from being selecting when Photoshop manages color. Perhaps someone with IOS could test this.
-
For patch target sheets, I just assign an arbitrary printer profile. It doesn't even have to be a profile for the printer you use but can be any RGB profile for any model printer. Then, I select Photoshop manages color and print using ICC disabled with the same printer device settings used for printing color managed images. The settings in Photoshop such as Perceptual, Relative, Absolute, and black point have no affect at all since Photoshop simply assumes that the RGB values, which are already in printer space, Are the same as whatever you select. Otherwise the null transform wouldn't work.
I can't say how this would affect ABW operation. I don't do B&W often but when I do, I have a special patch set with several hundred extra neutral, and near neutral, patches. I only use a profile made from this for B&W (in RGB color mode) though since it can create some odd profile characteristics in more saturated areas. At least with I1Profiler.
An ongoing concern I have with Adobe is that they will either prohibit this outright, or worse, round trip from device space back to Lab PCS then back to device space. So I test this with new updates just in case though I think it unlikely they will start doing it.
Why not just use the Adobe Color Print Utility which is designed to print without color management? I only use Argyll to do profiles (both color and ABW) and that's my method of choice.
-
Why not just use the Adobe Color Print Utility which is designed to print without color management? I only use Argyll to do profiles (both color and ABW) and that's my method of choice.
ACPU works fine as does I1Profiler direct, but I prefer being able to position multiple targets and control borders precisely which is easy to do in Photoshop. Once I'm in Photoshop, I prefer to print without leaving to run another app. And I have to be careful to replicate exactly the same printer device settings so more room for mistakes. Also, ACPU, for some reason, doesn't accurately size the images.
-
[...] Also, ACPU, for some reason, doesn't accurately size the images.
I usually enlarge image by additional 3 or 4% in printer driver to get the right size on page
-
Also, ACPU, for some reason, doesn't accurately size the images.
Yes, a well known bug that Adobe knows about and shows no signs of wanting to fix. I think the patches from Argyll end up about 4% smaller than they should be but it never is an issue reading them.
-
As an aside, since printer profiles are RGB in device space but PCSLAB on the other side. If Adobe decides to roundtrip the RGB values to PCS and back they have to go through the conversion. Since roundtripping is not error free the way to detect if this occurs is to compare a printed patch set against the stated, not color managed, results from ACPU. The simplest way to do this which would also show the greatest error is using a small color patch set along the 3D gamut boundaries. I use the 56 patch set generated by patchtool for this purpose. This patch set is all the RGB values with steps of 85 from 0 to 255 and the 3D boundary subset are the ones with at least one of the RGB values either at 0 or 255.
The reason this is effective is that the conversion from PCSLAB to RGB is particularly bad at the gamut boundaries. The cubes in the highest resolution I1Profiler profile are in steps of 7.1 along the a* and b* axes and errors are unavoidable. They average about 1 dE with a max of somewhat over 3 purely from the mathematical conversions. The printer itself adds a bit to this, but under .5 dE so it is quite easy to see if the printed, null transform set from Photoshop is consistent with that obtained from ACPU using this small set of patches.
I've attached the patch set if any are interested.
-
The thread is starting to wander, and we shouldn't lose sight that it started from a request for advice on ABW workflow.
The null transform works fine with any printer profile. At least in RGB space. Just assign any paper profile. It doesn't have to even be one for a paper you have or even printer you have as long as the profile is installed and a printer driver exists for that printer. ..... I can't say how this would affect ABW operation.
I was aware of that approach. The reason I didn't adopt it in this case was that I was trying to test the thesis, in that cameratico article, that the choice of profile to assign did make a difference to ABW. I didn't think that it did make a difference, and my results confirm that, but I needed to do the test under specific conditions. There are instances where the choice of tagged profile may make a difference. When we have discussed the null transform previously, Printfab was also mentioned as needing it to operate, and without rereading those threads I don't recall whether the choice of assigned profile has any impact on it.
I suspect this approach of using a printer profile to effect a null transform would work fine on Apples but I don't have an Apple to test it.
You don't need it on an Apple. This issue blew up in the last year or two because C'tein over on the TOP blog controversially advocated Printer Manages Color over a color managed workflow for color printing. In the comments section it was pointed out that this didn't work so neatly on Windows for the reasons that we've been discussing, and that the behavior also affected ABW. The different behavior between Windows and Mac remains puzzling, but it ain't going to change. It means ABW on Windows is less simple.
An ongoing concern I have with Adobe is that they will either prohibit this outright, or worse, round trip from device space back to Lab PCS then back to device space.
Your concerns are well founded because an Adobe engineer made that threat in the TOP thread. He was not at all sympathetic about the problems that the current behavior was causing, and the further problems that removing the null transform would create.
I regard ACPU as sufficiently broken on Windows as to make it useless for most purposes. If you are printing targets you can print from your profiling software. I only recommend it to those people whose printers I am creating profiles for remotely, as it is simplest for those unfamiliar with the intricacies of color management.
-
You don't need it on an Apple. This issue blew up in the last year or two because C'tein over on the TOP blog controversially advocated Printer Manages Color over a color managed workflow for color printing. In the comments section it was pointed out that this didn't work so neatly on Windows for the reasons that we've been discussing, and that the behavior also affected ABW. The different behavior between Windows and Mac remains puzzling, but it ain't going to change. It means ABW on Windows is less simple.
I believe you have this backwards. It is Apple that broke the printer pipeline several years ago and there was a long thread about this on LuLa. Eric Chan stopped making profiles for ABW driver because MacOS was not going to support their use. ABW on Windows has not changed one iota in the whole time I've been printing with Epson printers (9 years now).
I regard ACPU as sufficiently broken on Windows as to make it useless for most purposes. If you are printing targets you can print from your profiling software. I only recommend it to those people whose printers I am creating profiles for remotely, as it is simplest for those unfamiliar with the intricacies of color management.
I'm sorry but this is another puzzling statement. Why do you say it is broken on Windows. I use ArgyllCMS and it only generates targets; you need to print them outside of PS or LR and ACPU works just fine for that purpose. ACPU was designed to do one thing and one thing only, print out non-color managed targets for profiling. Of all Adobe products, the directions for ACPU use are the clearest I've seen: https://helpx.adobe.com/photoshop/kb/no-color-management-option-missing.html
-
I'm running in circles. If the whole purpose of printing a test chart is to objectively measure (with a spectrometer) how accurately the printer reproduces tone (I'm only speaking of Epson's ABW printing right now, and only speaking of Windows), then why in the world would you turn off the ABW driver before printing the test chart? How can we evaluate how well the ABW driver performs if we turn it off?
-
The thread is starting to wander, and we shouldn't lose sight that it started from a request for advice on ABW workflow.
Frep, thank you very much for noting that :-).
During coming weekend I will have more time to test new approach of generating new sRGB patch set within PS and printing it through ABW what should be the right workflow - then compare it to options #1-#5.
-
I believe you have this backwards. It is Apple that broke the printer pipeline several years ago
When I said "you don't need it on an Apple", I was referring to the null conversion trick. There isn't a silent profile conversion if you select printer manages colors on OS X.
What follows is something of a thread diversion, my apologies to the OP. There are different printing quirks on both Windows and Mac. My recollection is that the trio - Epson, Apple & Adobe - are all variously involved. One of the frustrating things is that these issues are not well documented. I'm not going to derail this thread by trying to rectify that here, and I'm not the best person to do that anyway.
We are talking principally about the quirks affecting Windows in this thread. The best place to read about them are in some comments by senior Adobe software engineer Dave Polaschek in these threads on TOP:
http://theonlinephotographer.typepad.com/the_online_photographer/2015/07/are-profiles-obsolete.html
http://theonlinephotographer.typepad.com/the_online_photographer/2015/07/andrew-rodney-on-the-importance-of-custom-printer-profiles.html
http://theonlinephotographer.typepad.com/the_online_photographer/2015/09/product-review-epson-surecolor-p800-printer.html
http://theonlinephotographer.typepad.com/the_online_photographer/2015/10/photoshop-vs-printer-managed-color-printing.html
Although I warn you in advance that trying to synthesise his comments in all these is a struggle. Dave is the most authoritative voice you'll find on the silent profile conversion problem on Windows. It's real. I've measured it. If you've not seen it in your workflow, well, I can't explain that.
On OS X, I wasn't assigning any responsibly for the removal of ICCs from ABW. There was a change made by Apple in 10.6.8 that caused Roy Harrington to write Print Tool. You can research this yourself if you want to want to understand it. As I said, both OS have their quirks, but they're different.
My comment on ACPU was too brief. Its placement on the page is broken under Windows, and I found that enough of a pain not to use or recommend it.
why in the world would you turn off the ABW driver before printing the test chart?
I've lost track of which comment this in is response to. I hope not one of mine. You don't turn it off. You turn off color management, and that is done in the Photoshop print dialog. In the Epson Dialog you select ABW and any options related to it.
@unesco: I look forward to your measurements.
-
Here is one link to the discussion several years ago about ABW, PS, and the OS: http://forum.luminous-landscape.com/index.php?topic=62900.0 I think my first post also has a link to the first discussion. Enjoy reading "old" history. I'm going to graciously exit this discussion as I really don't have anything else to offer.
-
Here is one link to the discussion several years ago about ABW, PS, and the OS: http://forum.luminous-landscape.com/index.php?topic=62900.0 I think my first post also has a link to the first discussion. Enjoy reading "old" history. I'm going to graciously exit this discussion as I really don't have anything else to offer.
Thank you Alan - worth reading!
-
I decided to abandon ABW QTR ICC printer profiling in favor of a more seat-of-the pants approach. I wouldn't be surprised if the results are just as good, either. Here's my plan.
Print out a variety of 2.2 gamma grayscale step wedge targets ( e.g. Keith's new chart (http://www.northlight-images.co.uk/test-image-for-black-and-white-printing/) )
Then fashion and save to disk a PS contast curve to make the test chart as seen on my monitor to match as close as possible to the chart as seen on print. All by eye and by hand only. No profiling software, no spectrophotometers, no OS pipeline workarounds. Just me and my reading glasses. If the printer is not 100% linearized straight out of the box, then so what. As long as the monitor matches the print, I'm good to go. I can soft proof 'till I'm happy.
Wish me luck.
-
I decided to abandon ABW QTR ICC printer profiling in favor of a more seat-of-the pants approach. I wouldn't be surprised if the results are just as good, either. Here's my plan.
Print out a variety of 2.2 gamma grayscale step wedge targets ( e.g. Keith's new chart (http://www.northlight-images.co.uk/test-image-for-black-and-white-printing/) )
Then fashion and save to disk a PS contast curve to make the test chart as seen on my monitor to match as close as possible to the chart as seen on print. All by eye and by hand only. No profiling software, no spectrophotometers, no OS pipeline workarounds. Just me and my reading glasses. If the printer is not 100% linearized straight out of the box, then so what. As long as the monitor matches the print, I'm good to go. I can soft proof 'till I'm happy.
Wish me luck.
It will be 100% perceptually linear approach!
-
I note a few comments about my B&W test image being in GG2.2 - this was always because I work in 16 bit GG2.2 for my B&W and the test image makes it easy to check ABW/Canon B&W modes.
Building QTR profiles from the test image was for linearisation purposes - something that has worked very well with some paper/ink combinations, but I find less and less need for (soft proofing never entered my considerations in this area)
Given the improvements in Printer B&W performance, I'm minded to note that measuring the linearity of ABW or Colour ICC profile based prints on the P5000 (using the 21 or 51 step patterns on the test image) and then creating a simple PS adjustment curve seems to be working rather well... Whilst the curve is 'by eye' it's based on the measured numbers from the test chart.
I tried out a P20000 yesterday and the ABW performance looked very good (Mk/Pk +3 greys) - I don't have detailed measurements for this, just a few -very- big nice looking prints (on TPP and CPN)
-
I note a few comments about my B&W test image being in GG2.2 - this was always because I work in 16 bit GG2.2 for my B&W and the test image makes it easy to check ABW/Canon B&W modes.
Building QTR profiles from the test image was for linearisation purposes - something that has worked very well with some paper/ink combinations, but I find less and less need for (soft proofing never entered my considerations in this area)
Given the improvements in Printer B&W performance, I'm minded to note that measuring the linearity of ABW or Colour ICC profile based prints on the P5000 (using the 21 or 51 step patterns on the test image) and then creating a simple PS adjustment curve seems to be working rather well... Whilst the curve is 'by eye' it's based on the measured numbers from the test chart.
I tried out a P20000 yesterday and the ABW performance looked very good (Mk/Pk +3 greys) - I don't have detailed measurements for this, just a few -very- big nice looking prints (on TPP and CPN)
The Ultrachrome PRO ink (P10000/20000) costs 3x that of Ultrachrome HD (P5000-P9000). Let us know if the PRO ink B&W prints look 3x better, as well
If I open your 2.2 gray gamma chart inside the aRGB 2.2G working space and print it from there, nothing bad will happen, correct? I work in aRGB and would like to stay there if no trouble.
Also, if I upsize your chart to fit on 13x19 paper (so that the 51 step patches are big enough for my Colormunki to read), will that cause any problems? And should I print your chart at my Pro 3800 printer's native 360ppi, or should I print it at 300ppi? Generally, I print at either 360ppi or 720ppi because that's what the experts say to do. But your chart comes as-is 300ppi.
-
>> The Ultrachrome PRO ink (P10000/20000) costs 3x that of Ultrachrome HD (P5000-P9000). Let us know if the PRO ink B&W prints look 3x better, as well
If you can define "3x better" ;-)
>> If I open your 2.2 gray gamma chart inside the aRGB 2.2G working space and print it from there, nothing bad will happen, correct? I work in aRGB and would like to stay there if no trouble.
Sure, I use images in A98 sometimes
>> Also, if I upsize your chart to fit on 13x9 paper (so that the 51 step patches are big enough for my Colormunki to read), will that cause any problems?
No - I did have a colormunki specific version of the 21 step, with chevrons (from back when the CM first came out)
>>And should I print your chart at my Pro 3800 printer's native 360ppi, or should I print it at 300ppi? Generally, I print at either 360ppi or 720ppi because that's what the experts say to do. But your chart comes as-is 300ppi.
Ah - beware experts ;-) This is in the try it and see if you can genuinely see any difference category - I will push up the print ppi if there is 'real' detail.
The chart works fine at 300 - if you want to use the checkerboard pattern for testing fine detail then you can print it a 'better' resolution. The question of 'optimal' ppi settings is often debated and I'll admit to comfortably printing some larger images at 240.
Interestingly, such resolutions were one of the areas I was chatting about yesterday wrt the P20000 - IIRC Epson have changed to multiples of 300 (like Canon and HP) - I need to check the details of this though (the specs point to native 600x600 as compared to 720x720 for the P7000)
-
Stranger and stranger.
I just ran a Photoshop print test on my Canon 9500II and Win 10 x64.
I created a chart with Lab values from Lab(50,0,0) to Lab(50,-99,0). I also converted the chart to Adobe RGB and sRGB to see how images in those spaces printed. I would note that Adobe RGB clipped the image starting at a=-64 and sRGB clipped starting at a=-36. Then printed them on glossy in the following modes:
Lab -> Photoshop manages Measured print colors clipped at a=-83
Lab -> Printer manages (ICC sel) Measured print colors clipped at a=-67
Image was converted to Adobe RGB then
aRGB -> Printer manages (ICC sel) Measured print colors clipped at a=-67 (same as Lab)
Image was converted to sRGB then
sRGB -> Printer manages (ICC sel) Measured print colors clipped at a=-39
I then changed the driver to select "driver managed (default)" instead of "ICC"
sRGB -> Printer manages (ICC sel) Measured print colors clipped at a=-47
Observations:
This is a Canon 9500 II on a Win x64. Results may differ on other configs.
As expected (my usual workflow) printing with color management disabled and "Photoshop manages color" provides colors to the edge of the printer's gamut at a=-83
Printing Lab images using "printer manages color" results in essentially the same print as first converting the Lab to Adobe RGB then printing with a clipping at a=-67
Adobe RGB is not transformed to sRGB when printing using "printer manages color"
Both sRGB images and Adobe RGB images print roughly correctly using the driver's ICC mode.
sRGB's colors are printed significantly more saturated when using "driver manages" in the device driver reaching a=-47 instead of starting clipping at a=-36 (sRGB gamut edge)
I'm not sure what to make of this except to note that I have noticed sometimes just printing quick cell phone snapshots (sRGB) often look better (love the greens) using the printer color management. Now I see why. They just increase the color saturation.
No idea how this would affect Epson ABW but it appears things are a bit complicated.
-
I note a few comments about my B&W test image being in GG2.2 - this was always because I work in 16 bit GG2.2 for my B&W and the test image makes it easy to check ABW/Canon B&W modes.
The core of the idea of my question in the initial post and then the following discussion is: how to generate that GG2.2 patch set (in PS). So, how have you done it?
-
As long as the monitor matches the print, I'm good to go. I can soft proof 'till I'm happy.
That's a very good point. Ultimately the objective is to get a print that we're satisfied with, and generally that means one that matches the monitor. With B&W there's more than one way to do that. Whatever works for you. My experience is that an approach based on measurement is easier and more robust.
Here is one link to the discussion several years ago about ABW, PS, and the OS: http://forum.luminous-landscape.com/index.php?topic=62900.0 I think my first post also has a link to the first discussion. Enjoy reading "old" history.
It is true that there have been a number of long and confusing Lula threads about printing with ABW and profiles, particularly on Mac, when it works, when it doesn't, and who is to blame. There was a lot of talking at cross-purposes, which we've repeated here to some extent.
The problem I've got with those threads is they don't address the issues of concern in this thread. Yes, you can print ABW from Photoshop using an ICC on Windows (and you print ABW from Print Tool using an ICC on Mac), but what if don't want to use an ICC on Windows? If you want to print from Photoshop, you have to be aware of the silent conversion problem under the printer manages colors setting and how to avoid it.
-
Adobe RGB is not transformed to sRGB when printing using "printer manages color" .... I'm not sure what to make of this ....
Me neither, partly because I don't fully understand the methodology or the results. For my part, I printed the standard 21x4 tagged as gray gamma 2.2 using printer manages colors, and again by converting to AdobeRGB and then assigning sRGB (thereby avoiding the silent conversion), and the results were quite different, mostly in the shadows.
-
Me neither, partly because I don't fully understand the methodology or the results. For my part, I printed the standard 21x4 tagged as gray gamma 2.2 using printer manages colors, and again by converting to AdobeRGB and then assigning sRGB (thereby avoiding the silent conversion), and the results were quite different, mostly in the shadows.
That is consistent with what I observed. The device driver, or some part of the Win 10 OS after Photoshop, is converting the RGB data it is receiving to the device RGB space and not just ignoring the source colorspace and not simplistically assuming incoming data is in sRGB.
The same B&W image in gamma=2.2 (Adobe RGB is also gamma=2.2), when assigned sRGB, will result in lighter patches in the darkest end of the 21x4 set if the different colorspaces are correctly converted. If the source colorspace was ignored the prints would match.
But what fascinated me is that the tests with the green patches indicates that the gamut of Adobe RGB is not truncated which it would be if converted to sRGB by the driver.
-
The core of the idea of my question in the initial post and then the following discussion is: how to generate that GG2.2 patch set (in PS). So, how have you done it?
The targets in the newer versions of the test image were created as CMYK targets in i1Profiler (for i1Pro and i1iO) simple K only targets.
If you wanted to make an arbitrary one in PS, you can create a new GG2.2 document, make a gradient block from black to white, then posterise to the number of steps needed.
The reasons for using i1Profiler was that it makes targets of just the right size to easily scan - it's also easy to specify targets numerically from a simple text file.
-
If you wanted to make an arbitrary one in PS, you can create a new GG2.2 document, make a gradient block from black to white, then posterise to the number of steps needed.
this is how I was going to do it today, thank you for confirmation
-
The core of the idea of my question in the initial post and then the following discussion is: how to generate that GG2.2 patch set (in PS). So, how have you done it?
ChartThrob? http://www.botzilla.com/blog/archives/000544.html (http://www.botzilla.com/blog/archives/000544.html)
-
I have made some tests today. Now I know more - but less...
Windows 7 x64, PS CC (updated), blank new image in: sRGB, AdobeRGB, GrayGamma2.2, all 16 bit, neutral gradient generated from pure white to pure black. Posterised to 21 steps.
Then, as for reference, I have measured in PS: RGB values and L values. sRGB patch set was identical to AdobeRGB (measurement using 8-bit numbers). GrayGamma2.2 very different to sRGB. Difference visible in the 1st and the 2nd figure.
Expressed in RGB values, source sRGB patch set is purely linear, but GrayGamma is partially linear, with strange artifacts especialy in shadows.
Expressed in L* values, source sRGB patch set is a bit convex with slight compression in shadows, GrayGamma similar but with severe shadow compression.
Then, I have printed sRGB 21 patch set in ABW (Neutral, Darker, Dark, 2880 dpi bi-directional, Printer manages color). Then measured with ColorMunkiPhoto. Results are in the 3rd figure (measured results have been normalised to 0-100 range).
Conclusion:
1) ABW Darker measurement results follows synthetic L* values from sRGB patch set. Differences are on L*=1 level, max=1.4, (for error discussion: only one print was measured, PS read 8-bit quantisation values with rounding errors from 16 to 8 bit conversion + ColorMunki imperfection). I would assume ABW Darker is linear in L* sense - it mimics L* source data.
2) ABW Dark differs from Darker, max difference L*= 3.4 - just checking in what direction the curve goes.
3) GrayGamma2.2 patch set generation attempt is strange, is it a bug in PS or I am silly and miss something?
Any more advanced comments then mine and interpretation is greatly welcome since I am a bit confused with some of the results.
[edit: Epson SC-P800, Ilford Smooth Pearl paper printed with PSPP settings]
-
ChartThrob? http://www.botzilla.com/blog/archives/000544.html (http://www.botzilla.com/blog/archives/000544.html)
thank you, I will read it carefully
-
I was looking at Scott Martin's site for another post earlier today and came across this article: http://www.on-sight.com/using-i1profiler-for-qtr-grayscale-measurement-and-profiling/
-
I was looking at Scott Martin's site for another post earlier today and came across this article: http://www.on-sight.com/using-i1profiler-for-qtr-grayscale-measurement-and-profiling/
Which aspects of it do you think are relevant for this thread?
-
I have made some tests today. Now I know more - but less...
I hesitate to comment on the test results posted so far, because I'm struggling to follow them. I'm not sure if that's just me, or whether ambiguities remain despite the best efforts of the posters to explain what they have done.
I don't understand this desire to generate new test charts. Perfectly good charts are available, particularly those that ship with QTR. They give equally spaced luminosity steps from 0 to 100 in a variety of patterns. They're untagged, which is fine. If you assign any grayscale profile you like, and measure, the data isn't going to change because you've only assigned the profile, not converted. The appearance of the chart on your monitor will change. If you convert to another profile, then with the exception of AdobeRGB (which has a gamma of 2.2), the measured data will change. but the appearance won't.
The general principle when creating an ICC - color or B&W - is you print with color management off. So as long as you do this then it shouldn't matter what space the test chart is tagged in. Your test charts generated from first steps should all work, since they should have 21 equally spaced steps from 0 to 100. The profile shouldn't affect the print, since color management should be off. The fact that the gray gamma 2.2 chart doesn't measure as having 21 equally spaced steps, if I interpret your results correctly, suggests to me that something has gone wrong with the generation of this chart. I honestly don't see the point of generating test charts from first principles, other than as an academic exercise.
Regarding your measurement of ABW Dark and Darker, a number of people of people posted comparative measurements of the five ABW tone settings. I went searching on the Digital B&W forum and found these:
http://forum.luminous-landscape.com/index.php?topic=104907.0
If you search more widely on the internet you'll find others. They vary with paper and printer.
The measurements I was suggesting on Windows to validate mine were these. Take an existing test QTR test chart. It's untagged. Assign it to gray gamma 2.2 and save a copy. Assign it to qtr-gray-lab and save a copy. Print these three files via ABW, using ACPU, since that's going to be the simplest way to ensure that color management is off, although the placement on the page is going to be inconvenient. Measure them. They should all be the same. That will demonstrate that the approach in the cameratico article doesn't work, if it ever did. So long as color management is off, the tagged profile will be ignored.
Now print them as is from Photoshop using printer manages colors and the same ABW settings. They will measure as different to the first three. I suspect that the gray-lab one will also be different to the other two. This will demonstrate that something has happened to them. (Based on the statements by Adobe software engineer Dave Polaschek I believe that this is caused by a silent conversion to sRGB by Photoshop. For reasons I don't understand, Doug Gray seems to conclude that it's happening elsewhere in the printing pipeline.)
If you want to print any of those charts correctly via Photoshop, rather than ACPU, you would have to convert them to the equivalent RGB ICC (AdobeRGB for gray gamma 2.2, rgb-lab for gay-lab), then assign sRGB, then print. If you compare these measurements, they will be the same as the ACPU prints. This will demonstrate that if you wish to print ABW from Photoshop using printer manages colors (and not using the ICC to print), then you'll have to use this trick to fool Photoshop into thinking that the image is in sRGB. Alternatively, you'll can use the null transform method in the print dialog - set the printer profile to be the document profile and ignore the scary Adobe warning.
(Edited for spelling)
-
I hesitate to comment on the test results posted so far, because I'm struggling to follow them. I'm not sure if that's just me, or whether ambiguities remain despite the best efforts of the posters to explain what they have done.
I don't understand this desire to generate new test charts. Perfectly good charts are available, particularly those that ship with QTR. [...]
Thank you Frep for your patience in all your replies.
I have made dozens of tests in the past week - generating from the scratch my own 21 and 51 patch sets directly in the PS CC (gradient posterisation, Windows7 as I intended and Keith recommended) in the following color spaces: AdobveRGB, sRGB, Gray Gamma 2.2, QTR Gray Lab (linear L*) and untagged files from QTR catalogue. Prints have been made in ABW Darker, Neutral mode (2880 dpi, bi-directional), Epson SC-P800 on Ilford Smooth Pearl paper. Color Munki spectro.
Conclusions:
1) All above mentioned variants gave the same results, shape of the curves were virtually identical (as presented a few posts before in the figure "L values - measurement.png"), max of differences is about 1.5 L*, but prints have been made in different conditions, different measurement modes - spot and strip, in different page orientation etc. Most of differences are within +-0.5 L* margin
2) Therefore, for Epson ABW test patch measurement under PS, untagged patch set can be used.
3) As a side effect, measuring a* and b* shows that 1440 dpi mode gives some more neutral print than 2880 dpi mode (Darker).
This week I am going to measure different options of ABW and parametrise them e.g. to be able to achieve linear print later on without measuring, using QTR scripts and struggling with PS color management options - I will share results here once they are ready.
-
This week I am going to measure different options of ABW and parametrise them e.g. to be able to achieve linear print later on without measuring, using QTR scripts and struggling with PS color management options - I will share results here once they are ready.
What working color space have you decided to use from here on out? I ask because the author of the aforementioned Cameratico.com article recommends using QTR-Lab working color space (I'm not talking printer profile, but rather working space PS>Edit>Color Settings). If your answer is QTR-Lab, then I must ask you this. Does the QTR printing GUI (module, pipeline, driver, thingamajig, whatever you call it) bypass the Epson ABW printer driver (like PrintImage and QImage RIPs do) and print with a 1.0 gamma response curve? If no, then what does the QTR printing GUI actually do that the printer ABW driver does not do? My experience with QTR was limited to building an ICC profile and nothing more--I've never printed directly from QTR itself.
-
Many years ago I needed to create specialized charts with superimposed sine functions of differing frequencies for studying system MTF. Linearity was important. It was a B&W image. I used the conventional approach using a custom profile and it worked reasonably well but I was able to refine it by creating an RGB target with all 256, 8 bit values. This was printed w/o color management then read with an I1. After loading it into Matlab, I smoothed it with a low pass filter as each step wasn't perfectly monatomic. Then created a reverse interpolation table. This was used in a function that read in a tiff file, applied the reverse table, and wrote out a modified tiff file. This worked even better. All I had to do was run the Matlab function to create a B&W image that was significantly more accurate than the best I got from a conventional profile using standard tools. It would be quite easy to create a command line program that could do something similar to get rid of the Matlab requirement. I suspect the open source Octave might be another route. I used standard color mode w color management disabled but it should apply to Adv. B&W just as well. Anyone tried something like that?
In retrospect I think that approach could be improved by grouping 4 pixels (at 720PPI on Epson) and adjusting them to improve the smoothness of each RGB step.
-
@unesco: #1 surprises me a little, because depending on how you printed these various test charts, I'd have expected some differences, but perhaps you printed them in a way to prevent this. #2 is what I would have expected. #3 is an interesting observation that I hadn't noticed before.
Does the QTR printing GUI (module, pipeline, driver, thingamajig, whatever you call it) bypass the Epson ABW printer driver (like PrintImage and QImage RIPs do) and print with a 1.0 gamma response curve? If no, then what does the QTR printing GUI actually do that the printer ABW driver does not do?
Qimage is not a RIP - it prints via the OEM printer driver. QTR is a RIP and as such it bypasses the printer driver entirely, including the ABW component of it. It just prints the luminosity numbers in the image file using the selected QTR curve. It's that curve that determines the response, because it specifies how much of each ink to use at each luminosity level. That's one of the attractions of QTR - you can get in under the hood and change its behavior using these curves in ways you can't with ABW. Most curves have been created to be linear in luminosity. In practice that varies from printer to printer, but QTR provides the capacity to linearize a curve for your printer. However converting to an ICC generated by QTR-Create-ICC before sending the image to QTRGUi, as recommended by some people, will change the overall response of your printing pipeline to something closer to a perceptual rendering intent.
@Doug: No idea. Out of my league.
-
What working color space have you decided to use from here on out? I ask because the author of the aforementioned Cameratico.com article recommends using QTR-Lab working color space (I'm not talking printer profile, but rather working space PS>Edit>Color Settings). If your answer is QTR-Lab, then I must ask you this. Does the QTR printing GUI (module, pipeline, driver, thingamajig, whatever you call it) bypass the Epson ABW printer driver (like PrintImage and QImage RIPs do) and print with a 1.0 gamma response curve? If no, then what does the QTR printing GUI actually do that the printer ABW driver does not do? My experience with QTR was limited to building an ICC profile and nothing more--I've never printed directly from QTR itself.
According to my previous post it doesn't matter what working color space the patch set was generated in PS when printed via PS, Epson Driver in ABW mode and "Printer manages color" (assuming it has been natively generated in PS). So, now I started my tests with untagged 51 random patch set I have generated with Argyll.
QTR printing is another story (I am not talking about using QTR "*.exe" scripts to generate icc). Since, QTR assumes linear gamma (=1.0), I convert my grayscale photo to QTR Gray lab .icc (linear L*) in the PS, save as LZW tif and open and print via QTR Gui.
Important thing is, as Frep has written, QTR has nothing in common with Epson driver and ABW. Prior to make your print, you have to prepare in QTR appropriate curve(s) for you print mode (resolution etc) and paper used. Spectro is needed, but you gain control on each color channel in the printer and proportion of how ink is mixed to make given shade of gray. That is not an easy task, and QTR has no clear documentation, but the result is really worth trying.
Many years ago I needed to create specialized charts with superimposed sine functions of differing frequencies for studying system MTF. Linearity was important. [...] I used standard color mode w color management disabled but it should apply to Adv. B&W just as well. Anyone tried something like that?
In retrospect I think that approach could be improved by grouping 4 pixels (at 720PPI on Epson) and adjusting them to improve the smoothness of each RGB step.
Doug, I have no problem with using Matlab, I used to be an expert in that excellent tool in the past - but would you be so kind to explain what do you mean in reference to simple patch generation? Especially, the issue of smoothness?
@unesco: #1 surprises me a little, because depending on how you printed these various test charts, I'd have expected some differences, but perhaps you printed them in a way to prevent this. #2 is what I would have expected. #3 is an interesting observation that I hadn't noticed before.
#1 new image created in the PS in given color space, patches generated in my PS by posterising gradients, printed in ABW and "Printer manages color" mode
#3 visually the difference between 2880 and 1440 dpi is slight, however in 1440 mode a* vs b* curve for L* going from 100 to 0 is more straight from the white point of the paper to the black point. In 2880 it is more curvy in midgray-to-shade area. The difference is at a level of dE=~1
-
Doug, I have no problem with using Matlab, I used to be an expert in that excellent tool in the past - but would you be so kind to explain what do you mean in reference to simple patch generation? Especially, the issue of smoothness?
Let's say we have the following measured results of patches created in steps of 1RGB deltas.
50,50,50 L=33.2
51,51,51 L=33.3
52,52,52 L=34.6
and the actual, smoothed over 5 RGB deltas at 51,51,51 is L=33.9
One could, perhaps, achieve better results by taking adjacent squares of 4 pixels and making two of them 51,51,51 and the other two 52,52,52.
My prior work would have only changed 50,50,50 to 51,51,51 as being the closest, printable RGB value to the smoothed target of L=33.9
My speculation is that this could be a refinement providing more smooth tones..
-
Let's say we have the following measured results of patches created in steps of 1RGB deltas.
50,50,50 L=33.2
51,51,51 L=33.3
52,52,52 L=34.6
and the actual, smoothed over 5 RGB deltas at 51,51,51 is L=33.9
One could, perhaps, achieve better results by taking adjacent squares of 4 pixels and making two of them 51,51,51 and the other two 52,52,52.
My prior work would have only changed 50,50,50 to 51,51,51 as being the closest, printable RGB value to the smoothed target of L=33.9
My speculation is that this could be a refinement providing more smooth tones..
O, I see - yes, I was considering that problem of not integer mapping of L* 0-100 range to RGB 8-bit 0-255 range. There are several options:
1) Dithering - PS is doing that, as far as I remember in case of 16-->8 bit conversion and/or posterisation.
2) Print and measure the full 256 patches set.
3) Design own dithering method as you suggest.
4) Use another software for printing which dithers at printer output generation level e.g. QImage.
5) Prepare and print patch set in 16 bit but this is virtually impossible in Windows.
The rounding max error is at 0.4 L* for given point so it could give 0.8 L* consecutive points difference. I think, that errors due to print non uniformity is at least comparable sometimes even at a level close to 2 L* (that's why not only multiple measures but also multiple prints are required). So, nice area to research in the future :-)
-
O, I see - yes, I was considering that problem of not integer mapping of L* 0-100 range to RGB 8-bit 0-255 range. There are several options:
1) Dithering - PS is doing that, as far as I remember in case of 16-->8 bit conversion and/or posterisation.
2) Print and measure the full 256 patches set.
3) Design own dithering method as you suggest.
4) Use another software for printing which dithers at printer output generation level e.g. QImage.
5) Prepare and print patch set in 16 bit but this is virtually impossible in Windows.
The rounding max error is at 0.4 L* for given point so it could give 0.8 L* consecutive points difference. I think, that errors due to print non uniformity is at least comparable sometimes even at a level close to 2 L* (that's why not only multiple measures but also multiple prints are required). So, nice area to research in the future :-)
Exactly so. Non-uniformity is one reason I used the Epson 9800 rather than the Canon 9500 II even when just printing 8.5x11 targets. The 9800 was much more uniform. Generally to the point where even the lower variations in the I1Pro required multiple passes to average out.
And there's the issue of changes, possibly due to thermal effects, that could occur based on the ink channels and activity level from the immediately preceding printing.
All in all, a complex set of issues.
-
According to my previous post it doesn't matter what working color space the patch set was generated in PS when printed via PS, Epson Driver in ABW mode and "Printer manages color" (assuming it has been natively generated in PS). So, now I started my tests with untagged 51 random patch set I have generated with Argyll. ..... #1 new image created in the PS in given color space, patches generated in my PS by posterising gradients, printed in ABW and "Printer manages color" mode
I don't have a lot more to offer on this, since you are on your way and getting seemingly consistent results. However one thing still puzzles me. If I print test charts with 21 equally-spaced steps in both gray gamma 2.2 and sRGB then I get different results, and the gray gamma 2.2 one looks a little odd, which I assume is from the silent conversion to sRGB. You don't seem to get that. It's possible that the effect is less marked on the PK paper that you're using. You should see it on MK papers.
Since, QTR assumes linear gamma (=1.0), I convert my grayscale photo to QTR Gray lab .icc (linear L*) in the PS, save as LZW tif and open and print via QTR Gui.
If you look in C:\Program Files (x86)\QuadToneRIP\icc you'll see a number of generic ICC profiles provided by Roy Harrington. The matte paper ones are, unsurprisingly, intended for printing on matte paper and the photo paper ones are for printing on gloss and semi-gloss papers. I'd need to dig around, but I seem to recall that the lab ICCs were intended as alternative generic editing spaces and not for printing with. You may want to check this, or perhaps ask on the Yahoo QTR group, where most expertise on QTR resides. You may not be doing what you think you're doing by converting to the lab ICC.
-
If you look in C:\Program Files (x86)\QuadToneRIP\icc you'll see a number of generic ICC profiles provided by Roy Harrington. The matte paper ones are, unsurprisingly, intended for printing on matte paper and the photo paper ones are for printing on gloss and semi-gloss papers. I'd need to dig around, but I seem to recall that the lab ICCs were intended as alternative generic editing spaces and not for printing with.
p.s. In my C:\Program Files (x86)\QuadToneRIP\icc folder there is a document gray-readme.rtf which is worth reading, as it explains Roy Harrington's intentions when creating the profiles in that folder.
-
p.s. In my C:\Program Files (x86)\QuadToneRIP\icc folder there is a document gray-readme.rtf which is worth reading, as it explains Roy Harrington's intentions when creating the profiles in that folder.
It always helps to RTFM.
-
It always helps to RTFM.
Yes, generally, but in this case the manual doesn't tell the whole story. My copy is dated from early 2005, and so the manual doesn't explain that the photo and matte ICCs are generic alternatives to ones that nowadays many people create themselves with an i1. Nor does it discuss the pros and cons of printing without color management, which some people in this thread want to try. But it does explain the intention of the lab profiles.