Luminous Landscape Forum
Raw & Post Processing, Printing => Printing: Printers, Papers and Inks => Topic started by: nikonuser on May 27, 2013, 02:17:29 pm
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I'm getting into more B+W images at the moment and use Silver EFEX Pro to do the B+W conversion before finally sharpening in Photoshop and printing on a 3880.
What are the advantages (or disadvantages) using ABW over just printing from Photoshop using the respective paper profile.
Thanks
Dave
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Having used both first on a 3800 and now on a 4900, I find the differences are subtle, so my recommendation is that you should try both and see which you prefer. Of course if you are using the Epson driver in ABW mode, you should not use Silver Efex Pro. ABW does the conversion from RGB and handles the profiling under the hood. Make sure your paper selection in the Epson driver is correct.
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Many Thanks, Mark, I was not aware of the possible conflict so having just tried ABW will now have a bash at B&W through Photoshop.
Dave
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And working with "Photoshop Manages Color" in the Epson driver, by all means do the conversion using SilverEfex Pro, (and select the correct printer profile for the paper you are using). It's a superb plug-in.
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... Of course if you are using the Epson driver in ABW mode, you should not use Silver Efex Pro. ....
Mark
I tend to use ABW after Silver Efex Pro. It seems to me that the adjustments I make, for what I think is a pleasing B&W, will probably not reflect the relative tonality of the colour image. I want to convert to B&W, work on the image, and see the B&W before printing!
Or are you suggesting that we should be using only PS (or in my case, LR) to make the B&W conversion and adjustments prior to using ABW? If so can you explain why you think using Silver Efex is sub-optimal?
Tim
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Mark
I tend to use ABW after Silver Efex Pro. It seems to me that the adjustments I make, for what I think is a pleasing B&W, will probably not reflect the relative tonality of the colour image. I want to convert to B&W, work on the image, and see the B&W before printing!
Or are you suggesting that we should be using only PS (or in my case, LR) to make the B&W conversion and adjustments prior to using ABW? If so can you explain why you think using Silver Efex is sub-optimal?
Tim
Well, I suppose there are three options: (1) RGB>ABW; (2) RGB>SFEX>ABW; (3) RGB>SFEX>PhotoShop Manages Color (i.e. No ABW). I do know that ABW was designed for option (1). I don't know what SFEX does to the data and how whatever it does to the data would interact with whatever ABW does. So I suggested not compiling one conversion on top of another. There is no reason to believe that an ABW conversion from SFEX would produce a result identical to what you developed in SFEX, so it could be a waste of time. But you know, it's only a bit of time and several pieces of paper to try all three options and see what you like best.
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Most of my prints end up as black and white. I have used Silver Efex Pro, and now prefer to make the conversion in Lightroom. Both S EFex and LR let you control how each color is translated to gray, and I cannot imagine ever wanting to leave the conversion to ABW (which is probably similar to blindly desaturating everything).
These days I always print using the Epson ABW driver on my 3800, but after I have done the conversion to grayscale.
So I'm in agreement with Mac Mahon about this. I want to see my conversion to B&W before I print. ABW does a beautiful job on grayscale images, IMHO.
Eric M.
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So Eric, is it your experience that once you've used SFEX or LR grayscale conversion, ABW reproduces what you did in SFEX or LR accurately? Because if that's the case it would seem to overcome the limitation of ABW that unless you use Eric Chan's profiles for the Epson 3800 you cannot softproof an ABW conversion.
(edited)
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So Eric, is it your experience that once you've used SFEX or LR grayscale conversion, ABW reproduces what you did in SFEX or LR accurately? Because if that's the case it would seem to overcome the limitation of ABW that unless you use Eric Chan's profiles for the Epson 3800 you cannot softproof an ABW conversion.
(edited)
Hi Mark,
Yes, subject to a few disclaimers:
1. I used Eric Chan's profiles for quite some time after I got the 3800.
2. I have settled on a small number of papers that I like (primarily Ilford Gold Fibre Silk and Canson Baryta Photographique).
3. More recently I have used the manufacturers' profiles with good results, and what I see on my calibrated screen, even without soft-proofing, looks very close to what the print looks like.
4. Point (3) of course depends on having a fair amount of experience comparing screen with prints, and learning to understand the differences.
5. I am "color blind" with the commonest red-green variety, so I have a good eye for gray scale differences, but not so with color. At one time I tried making some "subtle" (to me) adjustments in the ABW driver to try to simulate the look of a very slightly Selenium-toned darkroom print, and my photographer friends immediately complained about the ugly purple color, so I now use the totally neutral ABW settings.
I agree that it is perhaps impossible to soft-proof ABW images, but what Lightroom shows in the develop or print module is much easier to interpret than trying to visualize how a color image will appear as a B&W print.
Cheers,
Eric M.
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Hi Eric,
Yes indeed, I would never dream of trying to visualize a B&W print by looking at a full-colour version. I was asking more about the relationship between an LR-converted or an SFEX-converted print on your monitor, compared with what comes out of your printer using ABW, and that you answered in your point 3. That makes sense to me given the experience you have accumulated and the papers you are using. If you were doing this with matte papers I believe the proximity between monitor and print would be not nearly so close, hence calling for some kind of reasonably reliable softproofing.
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If one is still using WinOS (and there are some of us who still do ;D) you can use ABW profiles and soft proof B/W images. The principal advantage of the ABW driver is that it gives you an increased DMax and uses lesser amounts of color inks than printing B/W via the normal driver. The advantage of using profiles is to improve the linearity of the B/W response from the printer. There is a lot in the LuLa archives and elsewhere on this. For those using MacOS it's a different story and unless one wants to do a fair amount of trial and error work on images, it's probably best to use the normal driver. That being said, one can prepare a profile in the normal way and include a good B/W stepwedge set of patches which should help smooth out the printer response (I use 51 patches when doing my normal ICC profiles for just this purpose). The only way of preparing ABW profiles is to use Roy Harrington's QTR system under WinOS.
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Yes indeed, I would never dream of trying to visualize a B&W print by looking at a full-colour version.
Yet that is basically what a b&w photographer does every time he looks a scene and imagines what it would look like in B&W. :)
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If one is still using WinOS (and there are some of us who still do ;D) you can use ABW profiles and soft proof B/W images. The principal advantage of the ABW driver is that it gives you an increased DMax and uses lesser amounts of color inks than printing B/W via the normal driver. The advantage of using profiles is to improve the linearity of the B/W response from the printer. There is a lot in the LuLa archives and elsewhere on this. For those using MacOS it's a different story and unless one wants to do a fair amount of trial and error work on images, it's probably best to use the normal driver. That being said, one can prepare a profile in the normal way and include a good B/W stepwedge set of patches which should help smooth out the printer response (I use 51 patches when doing my normal ICC profiles for just this purpose). The only way of preparing ABW profiles is to use Roy Harrington's QTR system under WinOS.
Hi Alan,
I have not been able to compare results obtained printing with QTR profiles under ABW because I don't have access to that option. However, drawing on issues raised from the Ilford paper review, I have done further comparison work with the tonal settings in the ABW driver, and compared them with "Photoshop Manages Color" using the normal driver and Ilford's profile for GMS paper. Let us recall I am using Mac OSX 10.6.8 and an Epson 4900, with Epson driver version 8.64, the most recent for this combination of OSX and printer.
I made four prints of the Northlight Images B&W printer test target (1) Photoshop Manages with the GMS profile, (2) ABW-Normal; (3) ABW dark and (4) ABW Darker.
Firstly, contrary to what I thought, I discovered that every time the Epson driver is re-opened and ABW selected, the tone setting defaults to Darker. Hence the result we reported in the recent article on the Ilford paper is with the Darker setting (I hadn't noticed this nicety at the time). OK, so now we have results for all of them but Darkest, which wasn't necessary in terms of what I was looking for. I was interested in seeing differences of maximum black and tonal neutrality between the four settings, both visually and by the numbers. Outcomes are truly only moderately interesting - i.e. I find the differences subtle and the arguments for one or the other of these approaches somewhat academic. But for what it's worth, here goes:
For maximum black, L* is 4.9 for (1), 2.06 for (2), 2.05 for (3) and 2.93 for (4). I found this last result counter-intuitive so I repeated the reading and it was within 0.03 the same. Practically speaking however, when you look at these prints side by side close-up under a Solux bulb you see no difference in the blackness of maximum black.
For 50% gray, none of them reported 50% gray. (1) is 51.8, (2) is 55.9, (3) is 52.6 and (4) is 49.22. The really interesting observation from this result is that "50% gray" is considerably brighter in (2) than in (4), and the impact of this result is visible in the prints. I think it explains why the shadow detail is visually better reproduced in the ABW "normal" setting than in the ABW "Darker" setting once you emerge from the very lowest end of the tonal range in orderf to see any differentiation of anything under any setting. Between (1) and (2), I would give a slight edge to the deep shadow detail rendition of (2), and this is consistent with the numbers for L* in the gray readings (51.8 vs 55.9), but seeing the visual difference here requires a trained eye if you hadn't been pre-advised.
In respect of neutrality, none of them are truly neutral, a* and b* values never being zero, but some come pretty close. On the whole, not surprisingly, Photoshop Manages Color is the least neutral with a* and b* values of 0.54 and 1.17 respectively. It must be said - these are small differences, and it isn't until you look at this print compared to the others that the slight difference in hue becomes visible - this print is ever so slightly warmer to the eye, as the number confirm. All the results with the ABW driver are below zero, indicating a slightly cooler hue bias, again which only becomes noticeable compared with the warmer one. None of these results look intentionally "toned" when you see them in isolation. Print (2), ABW-Normal won the neutrality prize with a* and b* values of -0.26 and -0.77. The others were off by slightly larger absolute amounts, but the differences are trivial. hence the real winner from all four, if you like maximum shadow detail and neutrality is the ABW driver at the normal tone setting - I remind, for this combination of OS, printer and paper.
Then I compared what I saw on my display with each of the four prints, and given how my display is calibrated and profiled, (NEC PA271W, BasicColor 4, luminance at 110 cd/m3), the tonal alignment is closest to print (1) - Photoshop Manages Color, but also very close to # (2) - ABW Normal, because results (1) and (2) are really close for overall luminance above the very bottom of the tone scale. This coheres with Eric Myrvaagnes' finding #3 in his post above.
So going back to my first response to Dave, the OP, differences between the approaches are there but subtle, and much depends on the starting point you prefer, once you've run the tests. I would defer to you Alan on the numerical perspective for the linearity factor, as I cannot replicate your work on this point. I would say from a visual perspective however, that tonal representations between the display and the prints are very close in any of these results, save for what is going on at the very low end of tonal scale, as mentioned above.
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Yet that is basically what a b&w photographer does every time he looks a scene and imagines what it would look like in B&W. :)
Yes indeed, and so do I - at that level of basic appreciation - "is this the kind of scene or image that has the lines and contrasts that would make an impacting B&W print, or even more important, is this a scene or photo where colour dilutes the strength of the image". My remark was directed at a more detailed appreciation of the myriad of specific hues to grayscale. The latter - at least for me - is a tough judgment unless I make the conversion and try variations.
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Yet that is basically what a b&w photographer does every time he looks a scene and imagines what it would look like in B&W. :)
Some forty or so years ago I was in the habit of carrying two Pentaxes with me whenever I was out photographing, one with Kodachrome in it and the other with Panatomic X. My photographer buddies were amazed that I could go back and forth between color and black-and-white so rapidly. Of course in those days most of my previsualization was for monochrome anyway, since Mother Kodak had complete control of my color renditions.
Eric M.
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Hi Eric,
Yes indeed, I would never dream of trying to visualize a B&W print by looking at a full-colour version. I was asking more about the relationship between an LR-converted or an SFEX-converted print on your monitor, compared with what comes out of your printer using ABW, and that you answered in your point 3. That makes sense to me given the experience you have accumulated and the papers you are using. If you were doing this with matte papers I believe the proximity between monitor and print would be not nearly so close, hence calling for some kind of reasonably reliable softproofing.
Hi Mark,
First of all, thanks for your excellent reviews of the new Ilford papers.
And second, If you were doing this with matte papers I believe the proximity between monitor and print would be not nearly so close, hence calling for some kind of reasonably reliable softproofing.
is one of the reasons I stopped using most matte papers some time ago. The visual difference between monitor and print was always too great to judge without soft-proofing.
Eric M.
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Hi Mark,
First of all, thanks for your excellent reviews of the new Ilford papers.
And second, is one of the reasons I stopped using most matte papers some time ago. The visual difference between monitor and print was always too great to judge without soft-proofing.
Eric M.
Hi Eric, thanks - glad you found the papers review useful. And yes, as soon as Ilford and several other paper manufacturers came out with gloss/luster papers that bested Epson Premium Luster, whose surface, brittleness and hue tint never appealed to me, I made a definitive switch to Gold Fibre Silk as my preferred medium, because whether for B&W or colour, the DMax and gamut are much superior to any matte paper I've tried, and it handles well provided one is careful not to scratch the surface. To me these intrinsic qualities of the print are far more important than the surface feel of the paper, though I also believe that for some kinds of images matte texture and limited gamut can work very well, so no "hard and fast" rules. I have seen very rich-looking, beautiful B&W photographs printed on Epson Velvet or Moab, Hahn, etc. matte media, and of the latest Ilford offerings we reviewed, if I had to select one as my own preferred for matte printing whether colour or B&W it would be the Gold Cotton Smooth.
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.......... I would defer to you Alan on the numerical perspective for the linearity factor, as I cannot replicate your work on this point. I would say from a visual perspective however, that tonal representations between the display and the prints are very close in any of these results, save for what is going on at the very low end of tonal scale, as mentioned above.
Alan, me again, just taking up where I left off from last night, what I meant in the above sentence is that I cannot replicate the tests you did with QTR, and would see no need even if I could, because you've done it. What I can do, however, is either find or create a step wedge in known values of L* (I think 20 sections would be sufficient), print it on GMS using both ABW-Normal and Photoshop Manages Colour with the appropriate profile, read the patches from each and see which path deviates the least with respect to L* along the tonal scale. That could be moderately interesting and I may do it during the course of the week if time permits. There are some constraints here, but if I can get it done I'll report back.
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I'm getting into more B+W images at the moment and use Silver EFEX Pro to do the B+W conversion before finally sharpening in Photoshop and printing on a 3880.
What are the advantages (or disadvantages) using ABW over just printing from Photoshop using the respective paper profile.
ABW is a processing black box, does a very good job converting color images to B&W with limited control and no true way to see what you're doing. It uses less ink and is said to be more archival due to this process. You send a color image to ABW, fiddle with sliders on a preview that isn't your image and you're done. Those are the basic advantages.
IF you use another product to convert the color to B&W, viewing your image as you do so and producing a look you desire, sending it through ABW will re-convert it, you'll lose what you did. So you'll need to print that data without ABW using a good ICC profile. More control (more ink use, less archival, possibly color shifting and non neutrality issues due to profile, driver etc).
Both have advantages and disadvantages based on your goals and workflow.
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ABW is a processing black box, does a very good job converting color images to B&W with limited control and no true way to see what you're doing. It uses less ink and is said to be more archival due to this process. You send a color image to ABW, fiddle with sliders on a preview that isn't your image and you're done. Those are the basic advantages.
IF you use another product to convert the color to B&W, viewing your image as you do so and producing a look you desire, sending it through ABW will re-convert it, you'll lose what you did. So you'll need to print that data without ABW using a good ICC profile. More control (more ink use, less archival, possibly color shifting and non neutrality issues due to profile, driver etc).
Both have advantages and disadvantages based on your goals and workflow.
Andrew,
Several questions arise from this:
(1) I'd be curious to know whether any objective testing has been done to confirm the view that the ABW process is more archival, or is this a logical deduction based on views of the longevity of the individual inks involved in both processes?
(2) You are of course correct that ABW does its own conversion regardless of what one sends to it, but the discussion here, especially from Eric Myrvaagnes, seems to suggest interesting experience to the effect that at least with the two papers he mentioned, the empirical outcomes have adequate similarity between what he sees on his display converting and adjusting in LR or SFEX, and what comes out of the printer using ABW. I think that is a significant empirically supported finding of an experienced practitioner, even though for the reason you state, in principle it need not be that way.
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IF you use another product to convert the color to B&W, viewing your image as you do so and producing a look you desire, sending it through ABW will re-convert it, you'll lose what you did. So you'll need to print that data without ABW using a good ICC profile.
Hi Andrew,
Can you explain? If you have already converted a color image to grayscale, how can ABW do anything significant to change the image (other than adding overall color via the toning sliders)? As far as I can see, the "re-conversion" won't do a thing.
Eric M.
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Hi Andrew,
Can you explain? If you have already converted a color image to grayscale, how can ABW do anything significant to change the image (other than adding overall color via the toning sliders)? As far as I can see, the "re-conversion" won't do a thing.
Eric M.
ABW apparently messes with color space, how the driver lays down the ink, and gama, but it won't change your image editing at all. I convert to BW in Silver FX Pro and do substantial editing. I then save to Photoshop and make a few more image edits. I print through PS using ABW and the result is a near perfect match to the edited image on my monitor (I don't use the color tinting options in ABW.)
The only adjustment I make before printing is applying a subtle curve adjustment layer to slightly boost the near-black range which eliminates the shadow blocking I would get without it. But ABW has no way of knowing how to delete the edits you've made to the final image.
Sal
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What sold me to ABW is printing circular test gradients like the one from Graham Preston found at Northern-Images (http://www.northlight-images.co.uk/article_pages/black_and_white_test.html). These patterns will show up unpleasant color tone irregularities like nothing else.
At least on the 7900, as far as color tone linearization goes, ABW beats the color pipeline by a long shot.
QTR has the potential for perfect tone and color linearization, but I find the dithering pattern inferior to Epson’s (QTR doesn’t use variable drop size yet on the x900).
Now, ABW is a black box with no way to adjust color tone linearization. It was optimized for Epson papers which all contain OBAs. While ABW still beats the color pipeline on non-OBA papers, I wish there was a way to tweak the color tone in the highlights.
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QTR has the potential for perfect tone and color linearization, but I find the dithering pattern inferior to Epson’s (QTR doesn’t use variable drop size yet on the x900).
But if you set the output rez to 2880, I'm pretty sure it always only uses the smallest droplet size (at least that
s true of the Epson driver).
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But if you set the output rez to 2880, I'm pretty sure it always only uses the smallest droplet size (at least that
s true of the Epson driver).
QTR uses the Gutenprint driver which I don't believe uses small drop size in its QTR implementation for the x900. The x900 were only recently added to Gutenprint and QTR, as opposed to other Epson printers, so it could be unique to the x900s. Not sure.
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QTR uses the Gutenprint driver which I don't believe uses small drop size in its QTR implementation for the x900. The x900 were only recently added to Gutenprint and QTR, as opposed to other Epson printers, so it could be unique to the x900s. Not sure.
Seems odd to me, the minimum droplet size hasn't changed on the Epson wide format models since the 9800; 3.5 picoliter where the 9600 had 4 picoliter. The next droplet size on the 990 will be something like 10 picoliter, a size that should be quite visible. It is more likely that the 9900 dithering/weaving did improve beyond the Gutenprint driver.
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Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2012, 500+ inkjet media white spectral plots.
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On the HP Z models the B&W mode should be used with driver color management. HP recommendation. That CM expects either sRGB or AdoberGB as the assigned profile in the image file and is based on internal LUTs for the conversion. Like ABW it will accept Greyscale and RGB images. If the Greyscale image was kept in Gamma 2.2 during editing etc then I do not see what difference there could be between a "neutral" RGB image with AdobeRGB assigned or a Greyscale image with Gamma 2.2 assigned. Most likely the last is converted again to neutral RGB and it is assumed to be either AdobeRGB or sRGB assigned if the driver CM is not that sophisticated. The slight difference in the gamma curve of sRGB probably would not make a huge difference either. I guess the Epson ABW acts similar.
That still makes it possible to create a B&W QTR "ICC" profile for that ABW workflow, even when Greyscale images are used, at least in Windows. Third party media and individual printer characteristics can be compensated that way. The Dmax can be higher in a driver's B&W mode than in color mode and less color is mixed in on the B&W driver mode. Along the tone range the Lab a and b is not CM controlled so much depends on the choice of paper white and how warm the grey inks are. With a full CM controlled color workflow that aspect should be better but up in the shadows/black a warm carbon black ink on a cool paper still delivers a split with whatever CM profiling. If not you can bet the lower Dmax limits the image quality.
To say that an ABW workflow is meant to be used with RGB images and not Greyscale is something I can not agree with. I would not advocate either that ABW should not be used with "profiles".
--
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2012, 500+ inkjet media white spectral plots.
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The next droplet size on the 990 will be something like 10 picoliter, a size that should be quite visible. It is more likely that the 9900 dithering/weaving did improve beyond the Gutenprint driver.
Looking through a microscope at a x900 QTR/Gutenprint print, I only saw one size drop. And those drops were visible with the naked eye in the highlights.
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Andrew,
Several questions arise from this:
(1) I'd be curious to know whether any objective testing has been done to confirm the view that the ABW process is more archival, or is this a logical deduction based on views of the longevity of the individual inks involved in both processes?
As far as I know all the Epson pigment ink B&W tests Wilhelm Research did, started with the introduction of ABW (2400?) in the driver and used that driver and they all had a better fade resistance. I can not recall another driver being mentioned. The black generation in the different generations of ABW may have changed over time but it is still a B&W mode that has some color components in the mix. In some of the B&W tests the inks were not the limit in years but the paper white shift caused it. For example the 7900 B&W test with EEM that was set at 110 years because the EEM paper white in the archival test (another testing method) could not get beyond that number. A more or less arbitrary introduction of paper white shifting in the results. Aardenburg Imaging at least tests both paper white shift and the color shifting in the same test method.
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Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2012, 500+ inkjet media white spectral plots.
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Looking through a microscope at a x900 QTR/Gutenprint print, I only saw one size drop. And those drops were visible with the naked eye in the highlights.
That does not tell me whether it does not use the minimum droplet size. You could have seen the minimum droplet size. At the highest resolutions in the Epson driver the larger droplet sizes are not used. It is a 3.5 droplet size, with enough light and young eyes you can see dots like that. Ask Roy what the x900 lays down with QTR.
--
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2012, 500+ inkjet media white spectral plots.
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That does not tell me whether it does not use the minimum droplet size. You could have seen the minimum droplet size. At the highest resolutions in the Epson driver the larger droplet sizes are not used. It is a 3.5 droplet size, with enough light and young eyes you can see dots like that. Ask Roy what the x900 lays down with QTR.
Those drops were much larger than the smallest droplet size delivered by the Epson driver. I just emailed Roy. And I'll do some more testing this w-e.
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To say that an ABW workflow is meant to be used with RGB images and not Greyscale is something I can not agree with. I would not advocate either that ABW should not be used with "profiles".
I've been following with interest all of these threads lately regarding ABW printing using QTR-built profiles for linearization (which as Alan points out, can only be done reliably on the Windows platform these days). I've been printing with ABW now for quite some time on my Epson 7900 (without linearization profiles) and have the process fairly-well tuned in for my workflow which starts with drum-scanned 4x5 B&W negatives. I agree with Ernst that ABW is not meant just for RGB files. In fact, as Eric, Luc and others have implied, once you zero in on whether to use "Neutral", "Dark" or "Darker", and assuming you start with files which are Gamma 2.2 (very important for the ABW workflow), you will find that ABW works extremely well and predictably when starting with grayscale images.
Regarding using linearization profiles: I've just recently started testing this to find out if there is truly an advantage over the normal ABW workflow. I've carefully built my profiles using the QTR 51-step target, the QTR-Create-ICC-RGB utility (creates a standard ICC file with only Luminance information in it), and then printed my own custom B&W test target using the profile and ABW. The results? Well, I am quite surprised to see that shadow detail is actually slightly worse when using the profile. So far I cannot explain this, even after multiple attempts, re-checking my steps, and using different papers. Others using this procedure seem to find that shadow detail is improved with the profile; for me it is the other way around. One thing I have discovered: my 7900 in ABW mode is already EXTREMELY linear across the luminosity values in the 51-step target.
I plan to do some further investigation, including using M2 mode (UV-cut) instead of M0 on my i1Pro 2, but I have to say that so far I haven't found (in my case) that using profiles with ABW provides any benefit other than the opportunity to softproof. For some this could be important; for me it is less so because my workflow (using only a few papers) is already predictable enough.
Dave
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As far as I know and can figure out, 3.5pl drop size is what all the drivers are using.
That's the minimum stated in the Epson docs and its been the same for several generations
of Pro printers. At 2880x1440dpi only the one smallest dropsize is used. At 1440x720dpi
three dropsizes are used -- the larger ones seem to have varied a little from model to model.
Up through the x880 printers both QTR and Epson drivers used all the same API to the printer
so it was easy to compare the exact commands used. With the x900 and x890 printers Epson
has added a new API which is used by the Epson driver but not anyone else. So it might
seem possible that this works differently but they still quote 3.5pl as the minimum size.
Another thing to note is that although QTR and Gutenprint have a common root from way
back 10 years ago, all the tuning and handling of newer printers has been completely independent.
The other issue I want to mention is Mac color management with B&W printing -- ABW or QTR.
This used to work pretty well back in the old days -- CS3 and OSX 10.4 or 10.5 I think.
Eric Chan did ICC profiles for ABW on 3800 and 3880 I believe; QTR has had the capability
of creating grayscale ICCs for a very long time. Note that these do not handle "colors" --
just match the tonal gradation of B&W printing. But there's been a steady degradation of this
over all the versions since. With current versions (CS6 and Mt Lion) you can't even select
ABW with an ICC -- the Epson driver is also in the act of preventing this. With QTR you can
select profiles but you always get double profiling so its not very useful.
I got frustrated enough with this that I wrote a completely new print layout app that handles
all the color management the way is used to work -- B&W and color. Sorry about the commercial
plug but the program is called QTR-Print-Tool at www.quadtonerip.com -- free 30 day trial.
Roy
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Roy,
Welcome to LuLa...thanks for responding. I tested out your Quad Tone Rip recently for my upcoming The Digital Print book and really liked the capabilities. Somewhat frustrating that only USB seems to be supported (at least via Mac) but I got really nice results using 2 or 3 curve spit toning. I haven't gone down the rabbit hole of making curves or profiles but prolly will (but not for the book because of deadlines).
I still really like a full split-tone capability of using an ICC approach (for the right images) but prefer the QTR for more subtle toning not doable in the Epson nor Canon monochromatic options.
So, given the QTR default curves, do you have any ink usage data regarding which inks are used for the various curves?
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Regarding using linearization profiles: I've just recently started testing this to find out if there is truly an advantage over the normal ABW workflow. I've carefully built my profiles using the QTR 51-step target, the QTR-Create-ICC-RGB utility (creates a standard ICC file with only Luminance information in it), and then printed my own custom B&W test target using the profile and ABW. The results? Well, I am quite surprised to see that shadow detail is actually slightly worse when using the profile. So far I cannot explain this, even after multiple attempts, re-checking my steps, and using different papers. Others using this procedure seem to find that shadow detail is improved with the profile; for me it is the other way around. One thing I have discovered: my 7900 in ABW mode is already EXTREMELY linear across the luminosity values in the 51-step target.
I plan to do some further investigation, including using M2 mode (UV-cut) instead of M0 on my i1Pro 2, but I have to say that so far I haven't found (in my case) that using profiles with ABW provides any benefit other than the opportunity to softproof. For some this could be important; for me it is less so because my workflow (using only a few papers) is already predictable enough.
Dave
What you experienced is quite possible. There have been discussions on the dynamic ranges possible on different paper qualities and whether the L values are enough to get the best picture on every paper. Part of the problem could be that ABW is still a black box compared to QTR, the partitioning of the different inks over the tone range can not be controlled as much as it can be done in QTR. One can not edit the Epson media presets in ABW to that degree.
--
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2012, 500+ inkjet media white spectral plots.
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I take a day off from LuLa and see that there are a lot of posts on this topic now! Thanks to Roy Harrington for chiming in on QTR. Some points of observation. Andrew Rodney should have clarified that the ABW printer uses less color ink than the normal driver. With respect to 'permanency' of the prints made from the ABW driver, there is test data for some papers up on the Aardenburg website. I have submitted a number of tests (including a color patch set for comparison) for Hahnemuhle Photo Rag Ultra Smooth so those might give some indication about the relative stability of ABW versus the normal printing pathway. The Epson driver settings of normal, dark, darker, etc. are just gamma adjustments to the print and this has been shown HERE (http://gerryeskinstudio.com/ABW_sept08_paper/index.html) for the Epson 3800 (you need to go down and click on the Appendix link to get the data; and this reference has a lot of other good stuff in it); another thorough discussion is HERE (http://www.outbackphoto.com/printinginsights/pi045/essay.html#20070123).
Regarding the use of ABW profiles and whether they are more useful than a normal ICC printing path, this may be one of user preference. I would certainly advocate testing both on an actual print (the Northlight Images testprint is particularly useful as Mark Segal has already noted) and through measurements of a 21 step B/W patch set to insure that one's ABW profile is properly constructed. In using the ABW driver it's important to note that ABW profiles are strictly dependent on the 'tone' setting in the Epson driver. Of course this is all academic for MacOS users (I haven't looked at Roy's new approach that he outlined in his post as I'm on WinOS and QTR profiles still work for now).
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Alan, reverting to Reply 17, I see that QTR IS available in a Mac version. I doubt I'll have time to work with it over the near future, but I shall be complementing the material in reply 12 with additional measurements of L*a*b* deltas compared between ABW-Normal and Photoshop Manages Color, using one of Bill Atkinson's grayscale test ramps. I'll be reporting those results in this thread I hope some time today. This work of course is limited to my Epson 4900 and driver version 8.64 on Mac OSX.
Regarding the ABW tone settings, "just gamma adjustments to the print" are of course kind of important when you can actually see differences that impact on the character of the outcomes.
BTW - very dangerous indeed to take a day off from "LuLa". :-)
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Hello,
regarding the question of ABW vs ICC print in B&W I can share my humble opinion.
First of all, I think that maybe not all the printer model have the same behavior, and obviously there are differences depending on the paper used.
With a given paper, using my little R3000 (which is not a pro printer), adopting Adobe RGB (gray gamma 2.2) as working colorspace, there are some differences, as per L* linearity parameter, between printing a B&W image in ABW (neutral dark) and printing the same image with an ICC profile (provided by paper manufacturer for example).
That said, the first advantage of ABW is that, if for example in neutral-dark I get a similar non linear behavior as the ICC one (typical dark print shape) I can try a neutral-normal setting to counterbalance it, and this is not possible in native ICC without editing the image.
This gives you an option the have a better starting point for the print, but in my experience is far from perfect too
As already mentioned, other ABW advantages are the slight deeper black I have usually got (but not so much in some cases) and the probably higher archival grade due to some minimization of colored inks during the print. Again, here results may vary a lot more with a different paper choice.
What ABW it does not allow easily is the use of a linearization ICC.
A way to workaround this is the already mentioned use of QTR rgb ICC creation and a double ICC action (assign/convert) in RGB before sending the image to ABW driver.
Finally, what ABW cannot in any case allow is a gray tone neutralization (if needed for some papers, because normally in my test the neutral gray of ABW is better that the one of the ICC print on the same paper) and/or the desire to have a split-toned image (sepia shadows or whatever) without messing with the L* linearity.
Another issue could be the over-inking, but I will leave this argument out, for the moment.
In my opinion, the use of an ICC print in B&W makes sense if you need to overcome the gray neutralization and/or the spit-tone lack in ABW.
So, usually, my first choice for B&W print is ABW with a paper I have L* linearized and for which the gray tone is good enough.
If I need to print on a less neutral paper and/or want a custom split/tone I could consider to switch to an ICC B&W print, obviously using a L* linearization which includes the desired degree of neutral gray compensation (or split/tone).
There is a post regarding my approach to the L* linearization with/without tone compensation using DeviceLink profiles here:
http://www.luminous-landscape.com/forum/index.php?topic=78142.0
with some details regarding the current state of my experimentation/development and including some examples of real world results.
Unlucky at the moment is not something really usable or that I can share/provide: it is a bunch of scripts and batch files used under different applications, so it should be considered a experimental work in progress with unknown timing...
Nonetheless, I hope it will be useful.
Any opinion in regard is always welcome.
Ciao :)
Andrea
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Very good discussion.
When I was working with the 9880, I spent some time getting to know QTR and was able to get some good profiles (or curves as QTR calls them) for B&W printing. However after viewing the LuLa video series that covered the ABW I wanted to try it. I found that I was able to get very good results from it also on the 9880. When my 9880 finally gave up the ghost and I purchased the 9900, i stayed with the ABW (at that time the 9900 was not supported as it is now). Being able to soft proof in CS was a nice feature of QTR. (I am a windows user). Output from the ABW driver is excellent with deep rich blacks and very little if and color shifting when viewed in indoor lighting.
My current workflow for a B&W is to either convert in LR4 following steps from the Lula video series or Martin Evening's LR4 book or I will use Silver efex pro. Both are going to leave the image in RGB not greyscale. I then will use the Epson ABW driver and make the print, leaving the image in RGB. It's my understanding that the ABW driver needs to have the image sent in RGB not greyscale. I tend to print from the Neutral settings and just add a bit of contrast. The ABW driver gives very little feedback and I had hoped that with the 9900 Epson might improve on this as far viewing the settings changes.
I am going to revisit QTR, and if Roy is still checking this post, it would be great to see a new user's guide written. I realize this is time consuming and I would gladly being willing to pay for it. The problem is understanding the process of creating the curves for QTR, if you want to print from QTR. I never had any issue converting the curve to a profile for CS, I am assuming that process is the same as a year ago?
Paul Caldwell
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It's my understanding that the ABW driver needs to have the image sent in RGB not greyscale.
Nope...if printing from Photoshop (vs Lightroom) you can print RGB or grayscale...it doesn't matter. Lightroom doesn't really have a "grayscale" mode since everything is processed in it's internal colorspace.
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it would be great to see a new user's guide written. I realize this is time consuming and I would gladly being willing to pay for it. The problem is understanding the process of creating the curves for QTR, if you want to print from QTR.
I second this. Can someone explain in further detail the difference between QTR-Print-Tool and Quadtone RIP. I'm interested in buying if I can just wrap my head around it.
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Lively discussion, so I guess I should insert myself.
Jeff,
QTR is easiest to setup for USB with the automatic setup scripts. But you can manually set it up for various other connections. Bonjour is the preferred method -- it supports: ethernet, WIFI, and usb port on the Airport. (some of the older printers had firewire but that connection was not possible). Look at the Tutorial.pdf last couple pages for the details. The idea is to attach/create the printer in Print&Scan (Print&Fax in older OS's) and just use the script to add the curves.
If you'd like to see the ink usages of the various curves go to:
/Library/Printers/QTR/quadtone/<printername>/<curves>.quad
Double-click the .quad files or open them in QTR-CurveView for a graph of all the inks.
This is my take on the 3 basic ways to print B&W images on Epsons that I am familiar with:
1) Epson color driver
Pros: uses standard and familiar workflow including ICC profiles -- provided ones and custom ones. you can edit your file for split-tones etc, but its an extra editing step
Cons: uses more color inks which can give colorcast and metamerism issues
2) Epson ABW driver
Pros: uses less color inks, has some hue control of the image.
Cons: no split-tone, not planned for Color Management, B&W CM is not a huge issue because you can just edit your file with one AdjCurve to compensate. There are some builtin papers but you can't do any customizing for 3rd party papers.
3) QTR driver
Pros: uses least amount of color, split-tone builtin with lots of blending possibilities
its a pretty open system so a fair amount of 3rd party support for all kinds of setups.
Cons: if you want to grow your own there's a learning curve for doing that.
Industry standard ICC profiling has pretty much stuck with just color workflows -- RGB mainly plus CMYK for more advanced situations. (grayscale has always been in the ICC standard but rarely used). So for the 3 methods above only 1) has really embraced CM everywhere. Most anything your download from Adobe, Epson, paper manufacturers will be regular color ICCs.
I imagine confusion over using these color ICCs with either 2) or 3) has been a headache for a long time. This is probably why the triumvirate of Apple, Adobe and Epson have tried so hard to keep us from hurting ourselves. But that's made it hard for those of us who want to do our own thing -- hence Print-Tool.
They've actually done a pretty good job at convincing many of us. I've seen quite a few references to the notion that ABW is a "black box" so shouldn't be CM'd in the discussion. But all drivers and devices are essentially black boxes. We profile them so that a CM system can match screen views with printed output. The idea is to match LAB values because that's what we humans perceive. Color systems try to match L, A, & B, but grayscale tries to just match L.
The QTR program Create-ICC is just a simple way to create these grayscale ICCs for use with either ABW or QTR drivers. Note that there is an RGB version of this program but its still really just a grayscale ICC in an RGB format for programs/workflows that don't handle grayscale files or profiles -- which unfortunately seems to be becoming the norm.
None of this is really new -- been doing it since before ABW, but wrenches keep being thrown into the gears so its a never ending battle with the big guys.
Roy
(my point of view is mostly from the Mac side, PCs will be similar. But the big difference is QTR is not a driver there -- instead a separate program QTRgui which does no CM by itself)
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Alan, reverting to Reply 17, I see that QTR IS available in a Mac version. I doubt I'll have time to work with it over the near future, but I shall be complementing the material in reply 12 with additional measurements of L*a*b* deltas compared between ABW-Normal and Photoshop Manages Color, using one of Bill Atkinson's grayscale test ramps. I'll be reporting those results in this thread I hope some time today. This work of course is limited to my Epson 4900 and driver version 8.64 on Mac OSX.
Regarding the ABW tone settings, "just gamma adjustments to the print" are of course kind of important when you can actually see differences that impact on the character of the outcomes.
BTW - very dangerous indeed to take a day off from "LuLa". :-)
Yes, it is available for MacOS but you have to use the driver to print. WinOS allows you to print with the Epson ABW driver but with a dedicated ABW profile. You are correct about the tone settings and importance. It would have been nice if Epson would have programmed in a print preview feature so that you could see what the result might look like.
Alan
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I second this. Can someone explain in further detail the difference between QTR-Print-Tool and Quadtone RIP. I'm interested in buying if I can just wrap my head around it.
I admit more and newer docs would be good. Unfortunately there are so many possible levels to write it at.
There are some many combinations of OS version, printers, inks, profiling devices -- many of which I don't have.
Tom's doc is old and PC oriented but the concepts are all still the same. Amadou's workflow doc is Mac oriented but emphasizes that you don't need to "do it all". Hardly anyone needs to start from scratch. There's a lot of desire in the beginning to "do the best I can by customizing it all". Do the simplest workflow for a long time.
Print-Tool and QTR are two completely different products.
QTR is the long time printer driver for Epsons. It has all kinds of ways to control each of the individual inks for printing B&W images. It supports dozens of Epson printers and comes with curves (QTR profiles) for many combinations of printer and ink. It's pretty turnkey for most peoples needs.
Print-Tool (I probably should drop the QTR in front of the name) is a high level interactive program. Its for taking a piece of paper and laying out images, rotating, resizing and positioning. If you've used Lightroom Print module its similar. It's real easy to use and intuitive (at least I think so). It works with lots of file types and prints to any standard OSX print driver -- color or B&W. The main impetus was to do color management in a straightforward, correct and flexible way -- but altogether its a simple, easy print layout program. Its the only program I use for printing images -- with QTR for B&W, with Epson for color.
Roy
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Roy,
So, given the QTR default curves, do you have any ink usage data regarding which inks are used for the various curves?
Right clicking on any of the curves in the QTR curve setup box will give a graph of the curve.
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Print-Tool (I probably should drop the QTR in front of the name) is a high level interactive program. Its for taking a piece of paper and laying out images, rotating, resizing and positioning. If you've used Lightroom Print module its similar. It's real easy to use and intuitive (at least I think so). It works with lots of file types and prints to any standard OSX print driver -- color or B&W. The main impetus was to do color management in a straightforward, correct and flexible way -- but altogether its a simple, easy print layout program. Its the only program I use for printing images -- with QTR for B&W, with Epson for color.
Roy
A sorely needed contribution to the Mac platform! I will check it out Does it have any text handling ability such as control on adding titles, description, metadata to the page layout? I realize you are on an early version and that text can be added directly to image files by other software, so maybe that's asking too much, but my "go to" page layout-for-print software at this time is InDesign. Amazing control on both images and text plus full color management and even ability to print unflattened PSD files correctly. Sadly, InDesign's prohibitive cost, only to be made worse with Adobe's push to the cloud, rules an Indesign print workflow out for many of my colleagues, friends, and students.
cheers,
Mark
http://www.aardenburg-imaging.com
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A sorely needed contribution to the Mac platform! I will check it out Does it have any text handling ability such as control on adding titles, description, metadata to the page layout? I realize you are on an early version and that text can be added directly to image files by other software, so maybe that's asking too much, but my "go to" page layout-for-print software at this time is InDesign. Amazing control on both images and text plus full color management and even ability to print unflattened PSD files correctly. Sadly, InDesign's prohibitive cost, only to be made worse with Adobe's push to the cloud, rules an Indesign print workflow out for many of my colleagues, friends, and students.
cheers,
Mark
http://www.aardenburg-imaging.com
Mark,
Text is not supported now. But it is something I've thought of and its on the list of
potential features.
PSD files are supported but you need to save in compatibility mode which adds a flattened layer
as well as the traditional layers. I doubt that anyone but Adobe can support processing
Photoshop layers. (Aside: I think with the new Adobe CC licensing the compatible mode ought
to always be used so you can get a copy of your image if you ever stop paying).
Roy
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Mark,
Text is not supported now. But it is something I've thought of and its on the list of
potential features.
Roy
Not to worry. I just purchased Print Tool and quickly concluded it deserves a big round of THANKS for all us Mac users. I have been looking for an elegant solution for friends new to the MAC and for new photography and printmaking students as well to lift the absurd complexity of the Mac printing pipeline off their backs at least until they get more experience. Print Tool is it. Apple PAGES would have been good, but the printer pipeline is just as cumbersome and loaded with non sticky settings, bugs, and subsequent uncertainty as any other software currently running on the Mac save for a few Adobe applications (but those solutions are beyond financial reach for many). Your Print tool software handily eliminates that uncertainty. An added bonus: It provides a clean path to print non color managed ICC profiling targets but without the scaling quirkiness of Adobe Color Print utility.
My first wishlist request wouldn't be text. If would be an "Edit with" command that when you click on an image on the page layout and invoke the "edit with" command it would allow a simple round trip to and from one's desired image editing software. Rulers and full page layout with printer margins showing as dashed lines on the page would be good, too. I've got other ideas as well I will send to you offline, but even now, Print Tool is a very elegant answer to a printing bottleneck that has for many years exhibited seriously unMac-like behavior on a Mac for those of us who like to make prints from our photos.
cheers,
Mark
http://www.aardenburg-imaging.com
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Not to worry. I just tried Print Tool and quickly concluded it deserves a big round of THANKS for all us Mac users.
cheers,
Mark
http://www.aardenburg-imaging.com
Mark - no disrespect to Roy's efforts, but I'm curious - what does it do that Mac users can't do in the Lightroom Print module? I too would like a print function that accommodates text. It could come in very handy.
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Mark - no disrespect to Roy's efforts, but I'm curious - what does it do that Mac users can't do in the Lightroom Print module? I too would like a print function that accommodates text. It could come in very handy.
You can print without color management for one. That's useful for us Mac people.
The UI and overall functionality is ACPU on steroids, it doesn't appear to have scaling issues like the Adobe product. I purchased it, looks very nice although I think the price is just a tad high.
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Interesting comparison with ACPU Andrew, but my question is about comparison with LR's Print module. If it can do much more much better ............
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Interesting comparison with ACPU Andrew, but my question is about comparison with LR's Print module. If it can do much more much better ............
You can't print without color management in LR.
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Mark - no disrespect to Roy's efforts, but I'm curious - what does it do that Mac users can't do in the Lightroom Print module? I too would like a print function that accommodates text. It could come in very handy.
The Print module in LR has a fairly steep learning curve, IMHO, steep enough for me at least not to be willing to devote the time necessary to master it. Because I've mastered InDesign and InDesign can handle multi page text and graphics with ease plus give me a competent color managed workflow on a MAC (no small feat), I just didn't want to invest the learning time into LR's print module, although I use LR for cataloging and preparing RAW files for further editing in PS. If it works for you, then you've invested that quality time, and you can probably justify that effort as a reason to stay away from InDesign :D. For me, LR just isn't robust enough compared to InDesign, but as I noted in an earlier post, InDesign's steep financial cost and steep learning curve also makes it an impractical recommendation for many folks who simply want to print their photos cost effectively yet with decent color managed output.
Moreover, if a friend stops by and would like to make some prints, or I hold a weekend printmaking session for new students in my studio, I want MY friends and students, not me, to be able to print their photographs on any of the printers in my studio without having to get steeped in the whole LR workflow (unless LR is the reason for the class), or custom plugins/RIPs for specific printers, or InDesign for that matter. Mac users needed a clean and simple printer user interface that gets a color managed workflow right without having to jump over tons of unique app/printer driver hurdles. I.E., Learn one printmaking interface without a lot of blood, sweat, and tears. Print to any printer. Roy's Print tool is as good as it gets for this purpose on the Mac Platform. I'm not one to endorse products lightly, but frankly, I'd love to see Apple license Roy's Print Tool software to include this app free in the MAC OS and pay him to develop it a bit further always with a mind to keeping that sheer simplicity! Very Mac-like!
cheers,
Mark
http://www.aardenburg-imaging.com
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And one other thing. For less than $40, Roy just gave me a great fully color managed print pathway for my Mac independent of relying on any Adobe software of any sort. Maybe not Relcol w/bpc rendering intent, but I know a simple workaround for that. Adobe management... Are you listening? More interesting non Adobe software likely to appear in the months/years before perpetually licensed CS6 becomes a dinosaur.
regards,
Mark
http://www.aardenburg-imaging.com
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Seems odd to me, the minimum droplet size hasn't changed on the Epson wide format models since the 9800; 3.5 picoliter where the 9600 had 4 picoliter. The next droplet size on the 990 will be something like 10 picoliter, a size that should be quite visible. It is more likely that the 9900 dithering/weaving did improve beyond the Gutenprint driver.
Ok, this is embarrassing. I need to apologize to everyone (and to Roy in particular). I was wrong regarding the droplet size used by QTR. There is no difference in droplet size between QTR and Epson. I had confused the tests I ran a few months back with Gutenprint and QTR. :-[
As you said, Ernst, the difference is entirely in the dithering algorithm.
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.............. I doubt I'll have time to work with it over the near future, but I shall be complementing the material in reply 12 with additional measurements of L*a*b* deltas compared between ABW-Normal and Photoshop Manages Color, using one of Bill Atkinson's grayscale test ramps. ...................This work of course is limited to my Epson 4900 and driver version 8.64 on Mac OSX.
I've now had a chance to complete a series of measurements and I am providing them in the attachments. The observations from this information are as follows: (Please note these results are valid only for Ilford Gold Mono Silk paper printed in my Epson 4900 using the Epson Ultrachrome HDR inkset.)
L*:
"Read vs ref" means the values read off the print versus the value of L* on the target as measured in Photoshop. No method can print L*=0 blackness, but at the L*=0 file value, ABW produces about 2 levels lower lightness than the ICC profile. However, at that level of blackness, the difference is not visible on this (or perhaps any other) paper. By L*=3, ABW-Dark remains closest to reference values up to about L*=40. Thereafter, ABW-Dark and the ICC profile perform about as well (but in opposite directions) up to about L*=68. Thereafter, the ICC profile performs closest to reference values till L* gets into the mid-90s, at which point all of them are at their most deviant. From L*=3, ABW-Normal produces lighter results throughout than the other two, either because its positive variance is larger, os its negative variance is smaller, until approaching L*=100.
a*:
For both the a* and b* readings, the values shown are departures from 0 (neutral).
These measurements test for adherence to neutrality along the a* and b* axes (the closer to zero the readings, the better the neutrality). The most important observation about this data is that the variances don’t exceed 1/128th of the scale. That’s why it’s hard to perceive any green or magenta bias in any of these results. The largest deviations occur at the bright end of the scale where they would be less visible. The ICC profile on the whole shows less deviation from zero between L* levels 9 and 50. From L* 56 upward, ABW returns results marginally more neutral than the ICC profile.
b*:
This is the blue-yellow axis, and deviations from neutral here would influence the extent to which one perceives the print to be relatively warm or cool. To preface the observations, Ilford has informed the public in one of a previous Lula thread that IGMS does contain OBA. This would influence a spectrophotometer to return results with a bluish bias, however, the Pulse spectro I am using is UV corrected, which should mitigate this bias to an extent I have not tried to isolate. It think it likely that the OBA presence in this paper contributes to the somewhat negative bias in the b* readings. From L*9 onward, the ICC profile produces more neutral outcomes than the ABW settings, except in the range of L*68 to L*75, where they are clustered very closely, and again at L*94 to L*97. Having said all this, it is important to retain the fact that these long bars are measuring small differences, insofar as the maximum variance of about -1.50 is only slightly more than one percentage point of the scale on one side of zero.
The main conclusion I come to is that all this measuring is inconclusive. One needs to make prints and use what one thinks looks best. For example, in the Northlight B&W test page, I found a slight margin of preference for ABW Normal given how well it opens shadow detail, but the ICC profile is not far behind. Based on these tests, previous tests, and previous test prints using both an ICC and ABW-based workflow (but no QTR), I would normally opt for the ICC-based workflow because I really do like the ability to soft-proof my actual photos before sending them to print.
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In the previous post I reached my maximum of allowed attachments. There is one more, showing the grayscale target (from Bill Atkinson) from which I read the results. With this target the far left bar requires 3 readings top, center and bottom. The following bars require two readings - center and bottom, as the top of the bar measures the same as the bottom of the previous one. One can of course make more measurements of different values from this target as there are more discrete luminance values per bar, but I considered a total of 33 readings across the scale sufficient to see the main tendencies of interest.
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The main conclusion I come to is that all this measuring is inconclusive. One needs to make prints and use what one thinks looks best. For example, in the Northlight B&W test page, I found a slight margin of preference for ABW Normal given how well it opens shadow detail, but the ICC profile is not far behind. Based on these tests, previous tests, and previous test prints using both an ICC and ABW-based workflow (but no QTR), I would normally opt for the ICC-based workflow because I really do like the ability to soft-proof my actual photos before sending them to print.
Hello Mark,
many thanks for submitting your test data. it is really appreciated.
I have some small questions:
- the ICC used was the Ilford provided one or a custom one?
- It was used in relative colorimetric + black point compensation or in different way?
- regarding the a* and b* values of the white patch (paper white) I see a strange inconsistence for the ABW-normal case. Usually I never see this kind of difference in different instances of a paper white measurement. Are you sure do you have not accidentally swapped the a* with the b* values for this single wedge one (L* 100 of the ABW-normal set)? Because the other two are good matching and if you swap the a* and b* values of the not matching one (ABW-normal) it seems again a good match with the other two.
However I think that your measurements are not inconclusive at all.
I have taken your data and I made the same Lab graph I usually do for my linearization test for all the 3 cases you showed (ICC, ABW-normal and ABW-dark), you can find it in the first attachment.
The main difference is that I have highlighted the linear straight line (visible as dotted line) between measured black and measured white, because this line is my usual adopted reference target for my L* linearization.
- As visible, in the first (left) graph the ICC L* shape is a typical "S" shape, with slightly compressed shadows/highlights and slightly expanded midtones
- in the center graph the ABW-normal L* shape is always a little bit too high
- the right graph clearly show a quite good match of the ABW-dark L* shape with the theoretical linear target, this is clearly the best of the three if a true linear approach is desired.
Please, note this is not the first case I find this kind of coincidence.
In my second attachment you can find a similar comparison I have done using Ilford Gold Fibre Silk.
I used my Epson R3000 and Epson K3 VM inks. ICC was the Ilford provided one used in relative colorimetric and black point compensation on.
The strip was made of only 18 B&W wedges (not 33 like yours), the measurements were done with my humble ColorMunki.
- As you can see the ICC L* graph is not so good as yours, remaining always under the L* target line
- ABW-normal is very similar to yours, remaining always over the target line
- ABW-dark is the best of the 3, with good match to the L* target line and very similar to yours too
In ABW the gray tone is more neutral than the ICC one, and not so slightly bluish as the one you found (ColorMunki is UV-cut).
Overall in ABW the gray tone is very neutral, becoming a little bit warm only in proximity of the paper white, which is a bit warm for this paper.
In addition note that the L*, a* and b* values of the paper white is near perfectly matching in all the 3 cases.
In my humble opinion these data are very interesting because they show that the ABW modes provide results that are similar for a 4900 + Gold Mono silk and R3000 + Gold Fibre silk. (There is a little difference in the overall b* shape, but in different paper/coating/inks it could be expected).
Your ICC is clearly better performing that the one used in my case, ABW-dark is the best choice for L* linearity in my opinion and gives deeper blacks than ICC, but I agree with you that if you want to do some tone grading and you will be able to see on screen the results before printing, the ICC workflow is your solution.
I hope it will be useful.
Any comment is welcome.
Ciao :)
Andrea
-
Hello Andrea,
I like the way you prepared your graphs. They add another perspective.
I doubt that I swapped the a* and b* values for 0 in ABW Normal, but I would need to remeasure that patch to be certain. I'll look into it tomorrow and if there is a correction to be made I'll post it here. It could also be a glitch with the reading from the instrument itself. By the way, my Pulse spectro does have a UV filter.
The ICC profile used for these tests is the Ilford-supplied profile, RelCol with BPC and the paper selection in the driver is keyed to their recommended Epson paper.
You are correct that ABW Dark is somewhat more linear, but the differences compared with the ICC profile are not huge, so in the final analysis it boils down to which approach makes more satisfactory-looking photographs, and that would vary from one image to the next. That is why I think the exercise is fundamentally inconclusive even though one sees the technical differences. Linearity isn't a holy grail, it is a technical property which comparatively speaking either suits the image better or it doesn't. While the ABW delivers lower black values at L* = 0 than does the ICC profile, I, at least, can't see the difference on paper at that level of blackness and difference between the two. While it's good to know these differences quantitatively, in the final analysis, what I see is more significant than the data, because the ultimate objective is to enjoy the photographs one makes.
I think the main thing that distinguishes your b* results from mine is that IGFS has either no or very little OBA compared with IGMS, and that affects both appearance and readings regardless of the filter on both of our instruments.
I agree with you - there are some striking similarities between the two sets of results, especially after taking into account the basic differences between the two papers.
-
You are correct that ABW Dark is somewhat more linear, but the differences compared with the ICC profile are not huge, so in the final analysis it boils down to which approach makes more satisfactory-looking photographs, and that would vary from one image to the next. That is why I think the exercise is fundamentally inconclusive even though one sees the technical differences. Linearity isn't a holy grail, it is a technical property which comparatively speaking either suits the image better or it doesn't. While the ABW delivers lower black values at L* = 0 than does the ICC profile, I, at least, can't see the difference on paper at that level of blackness and difference between the two. While it's good to know these differences quantitatively, in the final analysis, what I see is more significant than the data, because the ultimate objective is to enjoy the photographs one makes.
Hello Mark,
many thanks for sharing your valuable experienced opinion,
I think that it is a very precious opportunity we have here and I really appreciate it a lot.
I'm glad you found interesting the way I analyzed/showed the data in the graph, by taking as reference the real potential straight line between printed black and paper white. I have adopted this approach as my standard evaluation tool and I always found it really useful for comparisons and for complementing my real world evaluations.
I have to admit that the Ilford ICC you used, even if not perfect, is a very good one, considering that it's not custom made. I dare to say is unusually good for a canned profile. :)
The Ilford ICC I have used in my test, with the same settings, is obviolusly less performing and too dark.
In my experience I have often observed this kind of deviations and even more.
For this reason usually I need/prefer to build a linearization curve: it provide me a reliable/consistent/comparable reasonably good starting point for all the work.
I fully agree with your points, the linear line target is not a holy grail, and the personal supervision is always the most decisive thing.
The reason why I said these kind of analysis are not inconclusive (probably misunderstanding the real "inconclusive" word significance, sorry for that) is because I think that these are really significant, providing some objective/repeatable information regarding how a real print could probably look on paper.
I know that one can figure it out by a visual inspection, but with a simple 18 strip and a graph you know immediately if the system is spot-on or not, how much, and where are the zones that are needing more attention, if any.
Based on my little experience by doing it consistently, it will greatly improve the personal knowledge allowing for less trial/error steps in the long run.
In addition, I full agree that each image needs a different "finished" look, and for this exact reason I prefer that the overall control regarding the related corrective actions, when needed, could be possibly performed by myself in the most transparent way, and not hidden in the ICC/print process in a not so consistent and/or easily predictable way.
In any case, as you perfectly said, the most important thing is to enjoy the photographs one makes.
Thanks again.
Ciao :)
Andrea
-
b*:
This is the blue-yellow axis, and deviations from neutral here would influence the extent to which one perceives the print to be relatively warm or cool. To preface the observations, Ilford has informed the public in one of a previous Lula thread that IGMS does contain OBA. This would influence a spectrophotometer to return results with a bluish bias, however, the Pulse spectro I am using is UV corrected, which should mitigate this bias to an extent I have not tried to isolate. It think it likely that the OBA presence in this paper contributes to the somewhat negative bias in the b* readings. From L*9 onward, the ICC profile produces more neutral outcomes than the ABW settings, except in the range of L*68 to L*75, where they are clustered very closely, and again at L*94 to L*97. Having said all this, it is important to retain the fact that these long bars are measuring small differences, insofar as the maximum variance of about -1.50 is only slightly more than one percentage point of the scale on one side of zero.
The main conclusion I come to is that all this measuring is inconclusive. One needs to make prints and use what one thinks looks best. For example, in the Northlight B&W test page, I found a slight margin of preference for ABW Normal given how well it opens shadow detail, but the ICC profile is not far behind. Based on these tests, previous tests, and previous test prints using both an ICC and ABW-based workflow (but no QTR), I would normally opt for the ICC-based workflow because I really do like the ability to soft-proof my actual photos before sending them to print.
Mark,
I do not share your opinion "all this measuring is inconclusive". Inkjet printing did improve a lot over the two decades that we more or less have access to it and part of that was in the tools we got for measuring. Calibrating the workflows offers us the consistent printing where we can build the individual corrections on.
Where you write that the Pulse Spectro is UV corrected, I would write UV-cut and delivering extrapolated/arbitrary numbers for the blue-UV range based on the longer wavelengths measurements. That is quite a difference. All UV-cut instruments + software act like that to my knowledge.
In the end your conclusion is correct about our eyes being the last check. For example your evaluation of the Dmax not being worth it as there is no discrimination possible between Dmax already that high. With enough light we can though but it is an interesting issue. Most of the time that high level of light is not available and not desirable. Printing for framing behind glass is subject to it, there is a loss of light already by putting glass in front and at a distance off the print. For matte papers we do get Dmax numbers that do create a real problem but in the lowest museum display conditions. With the matte papers the total dynamic range is more a limit than the display light level.
It would be interesting to see at what light levels the average eye can not distinguish detail in the shadow parts etc set against the Dmax. The light sources and sensors of our spectrometers are also challenged near 2.5 Dmax. And they work with a consistent light level which does not represent what we as observers experience. There must be some information available on this; one could create perceptual curves that combine the two variables of dynamic range and expected display light level. The Kruithof curve already shows us that display light level has an influence on what we like as color temperature at that light level.
The eyes will be the last check but also tell us that there is a limit in what we can measure and deduct. One conclusion is to skip that scientific part, the other to improve it. It is hard to say where the line has to be drawn. Creating a good image is an art but creating a good workflow is an art too in my opinion.
--
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2012, 500+ inkjet media white spectral plots.
-
Mark and I spoke on the phone the other day as he was finishing up his analysis as I had raised some of the issues following the nice review that he posted several weeks ago. I thought it might be instructive to do something similar with Museo Silver Rag, the paper that I print on the most. I decided to look at all the ABW tone settings from Light to Darkest (the dark tone settings are labeled according to increasing darkness on the data table). The reference data set is the normal Epson driver with no color management (I have an ICC profile for this paper that I made which includes a 51 step B/W patch set and I'll do some work to see how that compares in a couple of days). I've also calculated Dmax using Bruce Lindblom's on line converter. Patches were generated using ArgyllCMS (21 B/W step wedge) and read using the same software with an i1pro. I have not done the type to plots that Mark did nor how Andrea re-displayed them (I'm not the greatest Excel grapher and I just updated to Office 2013 which requires another learning curve; I'll try to get those done this week). However, there is a plot of four of the 'L' data sets showing how the curve changes with tone setting.
This paper has a better Dmax than Ilford Gold Fiber Silk according to my measurements (IGFS routinely measures 2.2).
EDIT ADDED: forgot to thank Mark for adding the descriptors to the chart!
-
Couldn't figure out how to post two things at once (it's Sunday after all). Here is the data set.
Alan
-
Hello Mark,
many thanks for sharing your valuable experienced opinion,
I think that it is a very precious opportunity we have here and I really appreciate it a lot.
I'm glad you found interesting the way I analyzed/showed the data in the graph, by taking as reference the real potential straight line between printed black and paper white. I have adopted this approach as my standard evaluation tool and I always found it really useful for comparisons and for complementing my real world evaluations.
I have to admit that the Ilford ICC you used, even if not perfect, is a very good one, considering that it's not custom made. I dare to say is unusually good for a canned profile. :)
The Ilford ICC I have used in my test, with the same settings, is obviolusly less performing and too dark.
In my experience I have often observed this kind of deviations and even more.
For this reason usually I need/prefer to build a linearization curve: it provide me a reliable/consistent/comparable reasonably good starting point for all the work.
I fully agree with your points, the linear line target is not a holy grail, and the personal supervision is always the most decisive thing.
The reason why I said these kind of analysis are not inconclusive (probably misunderstanding the real "inconclusive" word significance, sorry for that) is because I think that these are really significant, providing some objective/repeatable information regarding how a real print could probably look on paper.
I know that one can figure it out by a visual inspection, but with a simple 18 strip and a graph you know immediately if the system is spot-on or not, how much, and where are the zones that are needing more attention, if any.
Based on my little experience by doing it consistently, it will greatly improve the personal knowledge allowing for less trial/error steps in the long run.
In addition, I full agree that each image needs a different "finished" look, and for this exact reason I prefer that the overall control regarding the related corrective actions, when needed, could be possibly performed by myself in the most transparent way, and not hidden in the ICC/print process in a not so consistent and/or easily predictable way.
In any case, as you perfectly said, the most important thing is to enjoy the photographs one makes.
Thanks again.
Ciao :)
Andrea
Hi Andrea,
Yes, the LinFit function you used for measuring departures from linearity is very useful, and of course the kind of technique one deploys all the time in doing regressions and analysis of variance using Excel, (editorial rant: which over the years has become more and more convoluted as Microsoft complexifies the application for marketing purposes without adding any real value to it). So I much enjoyed seeing you take the trouble to bring that perspective to bear on the issues.
To be clear - I do think the measurements are worthwhile doing - for the reasons you state. My comment about them being inconclusive is that when I went back to the test prints of the Northlight B&W printer test page and compared what I saw in those photos relative to what the numbers were telling me, indeed the ABW Dark has a more linear L* outcome *by the numbers*, but the version printed with ABW Normal just looked a lot more interesting because the shadow detail was better revealed. So it's that kind of consideration - back and forth between the numbers and the photos for this particular exercise that prompted the comment I made. I'm the last one to declare a moratorium on arithmetic.
Turning to Ilford profiles - there was a time some years ago that they were truly quite poor. All that has changed. The latest crop (at least the ones for papers reviewed in our latest article) are probably hard to beat, so they have really gotten their act together on this - probably in response to feedback a number of us have been giving them over time. If you have not upgraded your canned profile for IGFS in the past while, I recommend you do so and see what results you get from it. It may or may not surpass what you can generate with the Colormunki - that I have no idea. I do most of my printing on IGFS and I use my own custom profile, generated with X-Rite Pulse Elite. I tested it relative to another profile I paid for from a very high quality external provider using the latest i12 profiling equipment and the results are very close - almost interchangeable, so I can use either. Depending on the printer model, the use of a canned profile can actually be quite satisfactory. The Epson professional printers (the Pro line) are manufactured to tight tolerances such that one unit is pretty much a clone of the other, explaining why many people are satisfied to use Epson's profiles supplied with the driver for Epson professional printers. I think for very exacting work, it still makes sense to do custom profiles, but the real need for this has become decreasingly acute over the past decade - again depending on the printer model and the acuity of the viewer's eyesight and expectations.
By the way, at level 100 in my Excel, I think I may well have switched the data between a* and b* for ABW Normal. Very sharp of you to pick that up. Thanks.
-
Mark,
I do not share your opinion "all this measuring is inconclusive". Inkjet printing did improve a lot over the two decades that we more or less have access to it and part of that was in the tools we got for measuring. Calibrating the workflows offers us the consistent printing where we can build the individual corrections on.
Where you write that the Pulse Spectro is UV corrected, I would write UV-cut and delivering extrapolated/arbitrary numbers for the blue-UV range based on the longer wavelengths measurements. That is quite a difference. All UV-cut instruments + software act like that to my knowledge.
In the end your conclusion is correct about our eyes being the last check. For example your evaluation of the Dmax not being worth it as there is discrimination possible between Dmax already that high. With enough light we can though but it is an interesting issue. Most of the time that high level of light is not available and not desirable. Printing for framing behind glass is subject to it, there is a loss of light already by putting glass in front and at a distance off the print. For matte papers we do get Dmax numbers that do create a real problem but in the lowest museum display conditions. With the matte papers the total dynamic range is more a limit than the display light level.
It would be interesting to see at what light levels the average eye can not distinguish detail in the shadow parts etc set against the Dmax. The light sources and sensors of our spectrometers are also challenged near 2.5 Dmax. And they work with a consistent light level which does not represent what we as observers experience. There must be some information available on this; one could create perceptual curves that combine the two variables of dynamic range and expected display light level. The Kruithof curve already shows us that display light level has an influence on what we like as color temperature at that light level.
The eyes will be the last check but also tell us that there is a limit in what we can measure and deduct. One conclusion is to skip that scientific part, the other to improve it. It is hard to say where the line has to be drawn. Creating a good image is an art but creating a good workflow is an art too in my opinion.
--
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2012, 500+ inkjet media white spectral plots.
Hi Ernst, please see my comment above to Andrea on the *inconclusiveness* matter. I fully support scientific analysis and the measurements that go along with it. I was talking specifically about the relationship of measurements to visual outcomes in the context of the particular piece of work I did.
I agree with you that there are issues with UV-cut instruments. It's a one-size-fits-all and some have argued cogently that they can confuse more than clarify. But the one I have is like that, so "faute de mieux" that is what I used. Better than nothing.
I too have been intrigued by the question of the level and degree of difference in L* numbers one needs before seeing differentials of deep shadow detail under normal viewing conditions, and I have tried to relate numbers to my visual perception. I find that much depends on the layout of the gradient; placing bars side by side one perceives much smaller differences than one does looking up or down for differences over a smooth array of gradually differing tonality. One thing for sure - at least for my level of visual acuity - I cannot see a difference of blackness between about L*2 and L* 3.7 read off of prints.
-
Couldn't figure out how to post two things at once (it's Sunday after all). Here is the data set.
Alan
Hello Alan,
thanks for your measurements set,
I can tell you I can try to put your data in my type of graph if desired,
but I kindly ask you a big favor:
can you put the data in a txt or csv or xls file instead of the jpeg one?
Because there are a lot of numbers, and from the jpg I have to write it manually one to one...
I was so curious that I done it manually for the Mark data set,
but it was time consuming (and error prone),
so if you could share a more numeric readable file I will do it more easily.
I assume your data are referenced to Gray gamma 2.2,
please confirm it because it is a required information for having a correct graph.
Many thanks for the attention.
Ciao :)
Andrea
-
Hi Andrea,
So sorry you went to all that trouble with my data. I could easily have sent you the Excel. If there is a next time, please just ask. :-)
Regards,
Mark
-
Hello Alan,
thanks for your measurements set,
I can tell you I can try to put your data in my type of graph if desired,
but I kindly ask you a big favor:
can you put the data in a txt or csv or xls file instead of the jpeg one?
Because there are a lot of numbers, and from the jpg I have to write it manually one to one...
I was so curious that I done it manually for the Mark data set,
but it was time consuming (and error prone),
so if you could share a more numeric readable file I will do it more easily.
I assume your data are referenced to Gray gamma 2.2,
please confirm it because it is a required information for having a correct graph.
Many thanks for the attention.
Ciao :)
Andrea
Check your LuLa message box and get back to me with an email address. Yes, the data should be in gray gamma 2.2. Targets were generated in ArgyllCMS and printed out with Adobe Color Print Utility with no color management at all.
Alan
-
Hi Andrea,
Yes, the LinFit function you used for measuring departures from linearity is very useful, and of course the kind of technique one deploys all the time in doing regressions and analysis of variance using Excel, (editorial rant: which over the years has become more and more convoluted as Microsoft complexifies the application for marketing purposes without adding any real value to it). So I much enjoyed seeing you take the trouble to bring that perspective to bear on the issues.
Glad you liked it (btw I use Libreoffice Calc and not Excel). It is not a "real" LinFit in math terms, I labeled it Linfit in the graph but it is a simple line from measured black to measured white points.
To be clear - I do think the measurements are worthwhile doing - for the reasons you state. My comment about them being inconclusive is that when I went back to the test prints of the Northlight B&W printer test page and compared what I saw in those photos relative to what the numbers were telling me, indeed the ABW Dark has a more linear L* outcome *by the numbers*, but the version printed with ABW Normal just looked a lot more interesting because the shadow detail was better revealed. So it's that kind of consideration - back and forth between the numbers and the photos for this particular exercise that prompted the comment I made. I'm the last one to declare a moratorium on arithmetic.
I agree with you, but nonetheless I like to add this additional tought:
if the Northlight B&W printer test image printed in ABW-normal was (and probably it is) more appealing, usually I ask myself this question:
- it is more appealing because of technical reasons (it is more similar to what I see on screen when compared to the others two prints)?
- or it is more appealing because of artistic reasons (I have done it in that way but after comparing the prints I have discovered I like it less dark in the midtones, even if this is not exactly what I see on screen)?
If the reason is mainly technical, I could accept to settle to ABW-normal as default setting, because maybe this means that there is a slight perceptive deviation between the on-screen image and the ideal L* linear print process. So, once confirmed, ABW-normal could become my overall good default setting for all the images I will print on that paper/printer/ink combination even if this profile is not the more linear one (as I know from my measurements).
But if the reason is something related to my personal artistic taste for that particular image, the most correct way I should address it is by editing the source image before printing, and not getting it in the print process as non-linearity side effect. In this case I tend to think I will stick to ABW-dark as general default setting for that that paper/printer/ink combination and edit that particular image to my tastes before printing.
Turning to Ilford profiles - there was a time some years ago that they were truly quite poor. All that has changed. The latest crop (at least the ones for papers reviewed in our latest article) are probably hard to beat, so they have really gotten their act together on this - probably in response to feedback a number of us have been giving them over time. If you have not upgraded your canned profile for IGFS in the past while, I recommend you do so and see what results you get from it. It may or may not surpass what you can generate with the Colormunki - that I have no idea. I do most of my printing on IGFS and I use my own custom profile, generated with X-Rite Pulse Elite. I tested it relative to another profile I paid for from a very high quality external provider using the latest i12 profiling equipment and the results are very close - almost interchangeable, so I can use either. Depending on the printer model, the use of a canned profile can actually be quite satisfactory. The Epson professional printers (the Pro line) are manufactured to tight tolerances such that one unit is pretty much a clone of the other, explaining why many people are satisfied to use Epson's profiles supplied with the driver for Epson professional printers. I think for very exacting work, it still makes sense to do custom profiles, but the real need for this has become decreasingly acute over the past decade - again depending on the printer model and the acuity of the viewer's eyesight and expectations.
Unlucky I tend to think that is difficult to make general assumptions on canned profiles and/or ABW settings.
My Ilford profiles are recent (I will re-check again in any case), but in my experience there is not valid proof that, if a particular canned ICC profile works good for a given printer/paper combination it will be perform equally good for another one. As you cans see My ilford ICC is far less satisfactory that yours.
If you look to Ernst thread "Gold standard",
http://www.luminous-landscape.com/forum/index.php?topic=78352.0
my last post is clearly showing that ABW-normal was my chosen best overall starting point (ABW-dark being too dark) and still it was not so good for the Gold Cotton Smooth paper as it is ABW-dark on Gold Fibre Silk.
If you desire, I can show you a graph of the Ilford ICC for that Gold cotton Smooth paper that is even more dark than the one of the Gold Fiber Silk I already showed.
But, as showed, ABW-dark was very similar for your 4900+MonoSilk and my R3000+FibreSilk.
For these reasons, I never trust in blind mode, and I always want to see what happens in my setup. Then, if the canned ICC (or a given ABW settings) it shows to be already good, this is a appreciated bonus for me.
As visible reading my few posts in this forum, at the moment I'm more focused on B&W print with related linearization/neutralization, and this is a simplified reality.
I know that for color ICC the things are way more complex and my ColorMunki could be really challenged (or become a limiting factor too) for really good results. I will see.
By the way, at level 100 in my Excel, I think I may well have switched the data between a* and b* for ABW Normal. Very sharp of you to pick that up. Thanks.
Thanks, I was simply lucky enough to notice it in the table and graphs :)
Ciao :)
Andrea
-
Hi Andrea,
So sorry you went to all that trouble with my data. I could easily have sent you the Excel. If there is a next time, please just ask. :-)
Regards,
Mark
Hello Mark,
no problem,
it was my personal curiosity to look inside your data and so I decided to do it.
It was not a big trouble, only a little bit annoying, so in the future if readable data are available, it could be easy for me to do the task.
Thanks for your willingness.
Ciao :)
Andrea
-
Glad you liked it (btw I use Libreoffice Calc and not Excel). It is not a "real" LinFit in math terms, I labeled it Linfit in the graph but it is a simple line from measured black to measured white points.
I agree with you, but nonetheless I like to add this additional tought:
if the Northlight B&W printer test image printed in ABW-normal was (and probably it is) more appealing, usually I ask myself this question:
- it is more appealing because of technical reasons (it is more similar to what I see on screen when compared to the others two prints)?
- or it is more appealing because of artistic reasons (I have done it in that way but after comparing the prints I have discovered I like it less dark in the midtones, even if this is not exactly what I see on screen)?
If the reason is mainly technical, I could accept to settle to ABW-normal as default setting, because maybe this means that there is a slight perceptive deviation between the on-screen image and the ideal L* linear print process. So, once confirmed, ABW-normal could become my overall good default setting for all the images I will print on that paper/printer/ink combination even if this profile is not the more linear one (as I know from my measurements).
But if the reason is something related to my personal artistic taste for that particular image, the most correct way I should address it is by editing the source image before printing, and not getting it in the print process as non-linearity side effect. In this case I tend to think I will stick to ABW-dark as general default setting for that that paper/printer/ink combination and edit that particular image to my tastes before printing.
Unlucky I tend to think that is difficult to make general assumptions on canned profiles and/or ABW settings.
My Ilford profiles are recent (I will re-check again in any case), but in my experience there is not valid proof that, if a particular canned ICC profile works good for a given printer/paper combination it will be perform equally good for another one. As you cans see My ilford ICC is far less satisfactory that yours.
If you look to Ernst thread "Gold standard",
http://www.luminous-landscape.com/forum/index.php?topic=78352.0
my last post is clearly showing that ABW-normal was my chosen best overall starting point (ABW-dark being too dark) and still it was not so good for the Gold Cotton Smooth paper as it is ABW-dark on Gold Fibre Silk.
If you desire, I can show you a graph of the Ilford ICC for that Gold cotton Smooth paper that is even more dark than the one of the Gold Fiber Silk I already showed.
But, as showed, ABW-dark was very similar for your 4900+MonoSilk and my R3000+FibreSilk.
For these reasons, I never trust in blind mode, and I always want to see what happens in my setup. Then, if the canned ICC (or a given ABW settings) it shows to be already good, this is a appreciated bonus for me.
As visible reading my few posts in this forum, at the moment I'm more focused on B&W print with related linearization/neutralization, and this is a simplified reality.
I know that for color ICC the things are way more complex and my ColorMunki could be really challenged (or become a limiting factor too) for really good results. I will see.
Thanks, I was simply lucky enough to notice it in the table and graphs :)
Ciao :)
Andrea
Andrea,
I don't usually do ABW. It comes up only when I'm writing an article where I think it appropriate to include for sake of thoroughness. I use a standard ICC workflow, my display is a high quality product (NEC PA271W) calibrated and profiled with what I think (based on profile analysis) for this display is now the preferable monitor calibration/profiling software on the market (BasicColor 4) and a custom-calibrated colorimeter provided for the display (this I could most likely improve by spending 800 dollars on a Discus, but I can't see the justification just now). The predictability of my outcomes between what I see on the display and what comes out of the printer using Ilford Gold Fibre Silk in an Epson 4900 is about 95% in terms of retained prints versus total prints. I think that's not too bad. With ABW I could not achieve this because it can't be soft-proofed and I simply don't have time to go through hoops simulating this. And I'm not all that hung-up on linearity because precise linearity is unimportant for the photos I make. These days I'm hardly rendering files. They come from the camera, into Lightroom and out from the printer in one seamless workflow, unless they need Photoshop for adjustments LR can't do, and then I still send them back to LR for printing. This is as true for B&W as it is for colour. For B&W I think LR's conversion option is fine and offers a lot of tonal editing flexibility with predictable outcomes. Using NIK Silver Efex expands into more exotic possibilities with very localized fine-tuning that doesn't need complex masking, so it's nice. I would add that most people probably hope they could use ABW to advantage without needing to go through all the hoops you have gone through - I saw from your DPReview forum article - months of work to get linear results. ABW is a respectable option - it has somewhat higher DMax (a doubtless technical quality but of dubious value as far as my eyes can see) and *can be* more linear than an ICC profile, not clear how much more neutral - depends on the ICC profile compared and the paper; so all in all, yes, it's an option, but perhaps less compelling than some make it out to be. I'm sure not everyone will agree with me about a lot of what I've just written here, but "vive la difference". :-)
By the way, with your interest in B&W printing, if you don't have it yet, you may find Vincent Versace's book "From Oz to Kansas" of interest. It's the most comprehensive book on Black and White conversion I've ever seen; however, I must caution - in all 250+ pages, there is not a mention of Epson ABW mode. Maybe that's why the sub-title of the book is "Almost Every Black and White Conversion Technique Known to Man".
All that said, you appear to be doing pioneering work with this tool, and if you have succeeded in making ABW perform better than what it does in its native state, congratulations and respect are in order, and for those who want to use ABW, they could perhaps benefit from what you have done.
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Andrea,
I don't usually do ABW. It comes up only when I'm writing an article where I think it appropriate to include for sake of thoroughness. I use a standard ICC workflow, my display is a high quality product (NEC PA271W) calibrated and profiled with what I think (based on profile analysis) for this display is now the preferable monitor calibration/profiling software on the market (BasicColor 4) and a custom-calibrated colorimeter provided for the display (this I could most likely improve by spending 800 dollars on a Discus, but I can't see the justification just now). The predictability of my outcomes between what I see on the display and what comes out of the printer using Ilford Gold Fibre Silk in an Epson 4900 is about 95% in terms of retained prints versus total prints. I think that's not too bad. With ABW I could not achieve this because it can't be soft-proofed and I simply don't have time to go through hoops simulating this. And I'm not all that hung-up on linearity because precise linearity is unimportant for the photos I make. These days I'm hardly rendering files. They come from the camera, into Lightroom and out from the printer in one seamless workflow, unless they need Photoshop for adjustments LR can't do, and then I still send them back to LR for printing. This is as true for B&W as it is for colour. For B&W I think LR's conversion option is fine and offers a lot of tonal editing flexibility with predictable outcomes. Using NIK Silver Efex expands into more exotic possibilities with very localized fine-tuning that doesn't need complex masking, so it's nice. I would add that most people probably hope they could use ABW to advantage without needing to go through all the hoops you have gone through - I saw from your DPReview forum article - months of work to get linear results. ABW is a respectable option - it has somewhat higher DMax (a doubtless technical quality but of dubious value as far as my eyes can see) and *can be* more linear than an ICC profile, not clear how much more neutral - depends on the ICC profile compared and the paper; so all in all, yes, it's an option, but perhaps less compelling than some make it out to be. I'm sure not everyone will agree with me about a lot of what I've just written here, but "vive la difference". :-)
Hello Mark,
many many thanks for sharing your opinions,
I'm a newcomer here, and I really appreciate it.
I don't want to steal further time to you, I perfectly understand that you have a very effective/proven workflow and this is what matters.
I have invested some month of time in my tool development (which is still under development) but I like to highlight that currently the time needed for single a ABW or ICC linearization is minimal.
The big time limiting factor is the wait for the ink to settle in the printed strips, but even for a 3 step process you are done in 3 days of wait (1 day for each pass due to ink settlement) and only some tenths of minutes of active work for the measurements, data manipulation, DeviceLink ICC creation.
By the way, with your interest in B&W printing, if you don't have it yet, you may find Vincent Versace's book "From Oz to Kansas" of interest. It's the most comprehensive book on Black and White conversion I've ever seen; however, I must caution - in all 250+ pages, there is not a mention of Epson ABW mode. Maybe that's why the sub-title of the book is "Almost Every Black and White Conversion Technique Known to Man".
Thanks for the book hint, I will look at it for sure.
All that said, you appear to be doing pioneering work with this tool, and if you have succeeded in making ABW perform better than what it does in its native state, congratulations and respect are in order, and for those who want to use ABW, they could perhaps benefit from what you have done.
Many thanks for your appreciation.
At the moment, in this field I'm only an humble enthusiast hobbyist, luckily I have some engineering skills, and I have simply tried to use it for this purpose.
Please, note that the tool is usable not only for ABW but for ICC linearization too (with optional gray tone neutralizing or grading in this case, if desired).
That said, I don't know if what I'm trying to do is something really uncovered or not, I tend to doubt it.
Maybe I could be simply one who has published/asked something on this regard, but I think that the big hardware/software makers in the color-management world have smart ideas and smart developers, so it could easily be that all (or part) of this is something already there and only hidden inside their products to protect their know-how.
Frankly, I don't know if I will ever further benefit from what I am developing more than what I'm already doing, i.e. by using this tool for my joy and my photo prints,
but time will tell. :)
Obviously any further opinion/suggestion will be always welcome and appreciated.
Thanks again.
Ciao :)
Andrea
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Mark and I spoke on the phone the other day as he was finishing up his analysis as I had raised some of the issues following the nice review that he posted several weeks ago. I thought it might be instructive to do something similar with Museo Silver Rag, the paper that I print on the most. I decided to look at all the ABW tone settings from Light to Darkest (the dark tone settings are labeled according to increasing darkness on the data table). The reference data set is the normal Epson driver with no color management (I have an ICC profile for this paper that I made which includes a 51 step B/W patch set and I'll do some work to see how that compares in a couple of days). I've also calculated Dmax using Bruce Lindblom's on line converter. Patches were generated using ArgyllCMS (21 B/W step wedge) and read using the same software with an i1pro. I have not done the type to plots that Mark did nor how Andrea re-displayed them (I'm not the greatest Excel grapher and I just updated to Office 2013 which requires another learning curve; I'll try to get those done this week). However, there is a plot of four of the 'L' data sets showing how the curve changes with tone setting.
Alan, thanks for having sent me the readable data.
I have tried to put it on my type of graphs.
Because your reference column is in K values and not in L* ones, initially I didn't know how to manage it.
There is a long time debate on the net regarding what kind of gamma Epson driver expect for ABW.
To convert from K values to L* values I need to know what kind of gamma to apply.
I have made a first group of graphs assuming a gamma 2.2 conversion.
Looking into it, I had the feeling something was not right.
In addition I have noticed that in "Epson standard" color mode the Epson driver is defaulted to sRGB (at least in my R3000 drivers), so I thought it could make sense for Epson to use the same default for expected encoded images printed via ABW mode.
For these reasons I decided to plot again all the data using a sRGB gamma curve for L* x axis reference calculations, instead of the gamma 2.2 previously used.
I have attached both the graph group for public evaluation, because I think it could be interesting to know all the opinion here.
As visible, the "sRGB" group is clearly more linear than the "g22" group. ABW-D1 (dark setting) is always the best of the bunch.
Usually I don't get the irregular deep-shadows zone behavior visible here in the gamma 2.2 test,
for this reason it could be useful to remark that these results are valid for this kind of printer/paper/settings combination, and, as already stated, it could not be convenient to draw more general conclusions from these data only.
In addition, looking to the b* shapes, the gray tone is not perfectly neutral (it's a little bit "cool"), and I have seen better results in ABW in other tests.
This paper has a better Dmax than Ilford Gold Fiber Silk according to my measurements (IGFS routinely measures 2.2).
This is strange, I get Dmax sometimes exceeding 2.4 with Gold Fibre Silk and I think I'm not the only one.
However,
I hope this was useful.
Any further opinion/comment is always welcome.
Ciao :)
Andrea
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(I have an ICC profile for this paper that I made which includes a 51 step B/W patch set and I'll do some work to see how that compares in a couple of days).
Alan,
if you have the data related to the above mentioned custom ICC built including 51 B/W steps, please, let me know, that I will try to compare it to the "Eposn std" and the "ABW" we have already seen.
Thanks.
Ciao :)
Andrea
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I have attached both the graph group for public evaluation, because I think it could be interesting to know all the opinion here.
Far from being of academic value only, graphs like these provide considerable insight to the photographer/printmaker if one understands how to interpret them. First, let me say to forum members here who are not familiar with this type of technical evaluation of photographic and printing systems that Andrea's plotting procedure is indeed the correct way to evaluate this data. He has appropriately plotted L*input on the x axis and L* output on the y-axis combined with a* and b* data plotted at + and - minus Y axis values along a horizontal mid axis and also corresponding to the L* input values for the patches from which they were measured. Such a graph as Andrea has plotted is the modern digital era's colorimetric approach to what classically was called an H&D curve in the film era of photography and follows in a tradition of photographic sensitometry dating back to well over a century in applied usage. It's difficult, however to teach folks how to interpret them without the benefit of being in a classroom where a pointer can be used to highlight aspects of each graph easily and where questions and answers can can flow more quickly. That said, I will attempt to point out a couple of features to a few of the graphs, and that perhaps may help.
1). A perfect system for L* tone reproduction would follow a 45 degree straight line stretching from L* 0 to L*= 100. Imagine (or draw) a dashed line like this on all of these graphs. The slope or gamma if you will of this line = 1 and that's the ideal aimpoint reproduction. However, no printer/ink/paper achieves an L* max= 100 and no printer/ink/paper reaches a black ink on paper value of L* = 0, which means Andrea's choice of straight line linearization as the goal is one logical approach, but visual contrast over all tones is nevertheless forced lower in order to achieve. Glossy papers with high whitepoint and rich blacks get closest which is why producing "prints that match my monitor" is easier with said papers compared to mat fine art papers (or worse yet plain uncoated papers). Note that compared to the ideal gamma 1 objective, all of the graphs from Epson Standard to ABW light and dark all follow a rendering theme dancing in and around Andrea's full linearization approach. This result is logical because all are useful as starting points for various print reproduction objectives, with some better for some images and viewing conditions than others. It depends on the application objective and what parts of the global curve one wants to tackle with additional image edits (more curves and selective dodging and burning to emphasize certain areas of a particular image. I will try to highlight a few examples that hopefully may help folks come to their own useful interpretations.
2). The curve for ABW Light: This aimpoint curve provides the lightest print and with the most open shadow detail by virtue of of L*output running higher than L* input values over all of the curve except anchored at L* max and L* min to what the ink/media can provide. Such a curve is a good starting point for image reproduction if one Knows the print will be displayed under relatively dim lighting conditions, Viewers will judge print quality best under these conditions, but the downside is when the print is displayed under better lighting conditions it will look more washed out (light and lacking image contrast in highlights and midtones albeit with good shadow detail).
2). ABW Normal, ABW Dark, ABW darker: The curve progression between these rendering choices goes in the predictable direction it needs to in order to produce gently increasing darkness in the overall tonal rendering. ABW Normal nicely splits the difference between ABW light and ABW dark but still errs slightly in the direction of an overall lighter print. Epson as well as other manufacturers typically regard this type of tone reproduction as "normal" because many studies show that the majority of prints out there in the real world are still displayed under less than optimal lighting, hence will be helped by a "normal" tonality erring on the lighter printing side of the straight linearized tone reproduction curve.
3). Example 3). The Epson Standard result: This is a bit surprising but may be the result of the media settings used. Typically, for Epson consumer printers printing sRGB color images, the Epson standard controls (Epson's hardwired controls in the driver for consumers who don't know about ICC profile) produces a curve that is shaped like this one, but again typically errs in the mid tones through the 3 quarter tones slightly lighter and thus above a fully linearized curve like Andrea chooses to use. This test result for Epson Standard mode boosts mid tone contrast at the expense of shadow reproduction as I would have expected, but I would also have expected the mid tone region boosted also lighter than what we see here. Note again that shadows are compressed more hence lower contrast, but midtones are getting a boost in contrast. One will have to dodge shadows to open them up more if this curve is used as a starting point, but less work would have to be done to mid tones and highlights to achieve good visual contrast overall. What's more interesting in this plot is the b* dip which occurs at about 45 L. See item 4 below.
4). To have perfect monochromatic neutral under a specified illuminant condition (e.g. D50) across all tones in in a B&W print requires a flat curve parallel to the horizontal zero line for both a* and b*. Many inkjet papers on the market today vary from bright white to warm white color, and this range of media color typically plots between b* = -10 to +5. Also, many PK and MK inks don't always achieve a perfect b*=0 on all media. Hence, the a* and b* curves must also bend to accommodate printing system realities, but gentle gradual bending is visually better than lots of bumps and dips. That said, one shouldn't get alarmed at + or - deviations less than or equal to approximately 1.0 because much of that is simple instrument and patch measuring repeatability. However, when you see rapid dips or bumps at 2.0 a* or b* difference over smalL L* difference on these plots as seen in the Epson Standard curve plot at the 45 L* tone, such dips start to become noticeable as unwanted "color ripple". Some people are more sensitive to these color variations in B&W prints than others, but ABW mode in these graphs shows it's handling the hue gradation across the tone range better than the Epson standard mode in this test. Note also that even ABW mode shows a relatively rapid change in b* value as shadow tones near L* minimum. This is where the Epson driver is switching over to PK or MK black ink and feathering out the other gray inks and colors. This would be a noticeable issue too, but the saving grace is that it's occuring at the lowest L* values in the print. The often quoted rule that humans can see delta E changes as small as 1.0 is a good general rule of thumb but it's not perfect. As tones get darker, our visual color discrmination gets poorer, so a 3 0r 4 unit discrepancy in the very darkest part of the print will generally not be likely seen as that dip 2.0 b* dip occuring at the 45L location in the Epson Standard graph. Lastly, that the hue of Silver Rag gradually moves from slight positive 2.0 b* value at media white point (i.e., it's a slightly warm colored paper) to a -2.0 value over the tone range and then back up again as dmax (l*min) is approached is providing an ever so subtle split tone effect for this ink on this paper with this Epson driver, but overall would be judged as a very neutral B&W print with no unwanted color ripple (except for possibly in the Epson Standard mode at the b* dip occurring at L45).
My post has gotten very long which is the nature of this type of analsis, but I hope it helps more folks reading this thread to get a better sense of how to interpret these plots. They are indeed very informative of tone reproduction behavior of the different rendering modes for the chosen printer/ink/media.
regards,
Mark
http://www.aardenburg-imaging.com
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3). Example 3). The Epson Standard result: This is a bit surprising but may be the result of the media settings used. Typically, for Epson consumer printers printing sRGB color images, the Epson standard controls (Epson's hardwired controls in the driver for consumers who don't know about ICC profile) produces a curve that is shaped like this one, but again typically errs in the mid tones through the 3 quarter tones slightly lighter and thus above a fully linearized curve like Andrea chooses to use. This test result for Epson Standard mode boosts mid tone contrast at the expense of shadow reproduction as I would have expected, but I would also have expected the mid tone region boosted also lighter than what we see here. Note again that shadows are compressed more hence lower contrast, but midtones are getting a boost in contrast. One will have to dodge shadows to open them up more if this curve is used as a starting point, but less work would have to be done to mid tones and highlights to achieve good visual contrast overall. What's more interesting in this plot is the b* dip which occurs at about 45 L. See item 4 below.
Mark, the data that Andrea worked up was from me. The Epson Standard result was simply printing the monochrome patch set from ACPU with no color management in the Epson driver. I will be printing out the same patch set using an ICC profile that I made that includes a full B/W patch set. I would assume this will give a different result than the one displayed.
Alan
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Mark, the data that Andrea worked up was from me. The Epson Standard result was simply printing the monochrome patch set from ACPU with no color management in the Epson driver. I will be printing out the same patch set using an ICC profile that I made that includes a full B/W patch set. I would assume this will give a different result than the one displayed.
Alan
Ok, that explains the dark tone scale rendering. I guess I wouldn't have called it Epson std mode. It's NCA, i.e., "no color management" mode with the Epson driver and represents the full ink ramp of the chosen media setting, thus no changes in RGB data values being sent to the printer. I tend to reserve the term Epson "Standard mode" for the way Epson uses it, which is when sending a straight sRGB tagged image (in this case perhaps preconverted to RGB neutral triplets) to the Epson driver set to "standard" not "vivid" or "Adobe RGB" mode using the Epson color control menu. This menu is Epson's built in "easy" color management pathway for amateur photographers shooting sRGB jpegs and not wanting to learn how to set up a full color managed workflow using ICC printer profiles.
cheers,
Mark
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3). Example 3). The Epson Standard result: This is a bit surprising but may be the result of the media settings used. Typically, for Epson consumer printers printing sRGB color images, the Epson standard controls (Epson's hardwired controls in the driver for consumers who don't know about ICC profile) produces a curve that is shaped like this one, but again typically errs in the mid tones through the 3 quarter tones slightly lighter and thus above a fully linearized curve like Andrea chooses to use. This test result for Epson Standard mode boosts mid tone contrast at the expense of shadow reproduction as I would have expected, but I would also have expected the mid tone region boosted also lighter than what we see here. Note again that shadows are compressed more hence lower contrast, but midtones are getting a boost in contrast. One will have to dodge shadows to open them up more if this curve is used as a starting point, but less work would have to be done to mid tones and highlights to achieve good visual contrast overall. What's more interesting in this plot is the b* dip which occurs at about 45 L. See item 4 below.
4). To have perfect monochromatic neutral under a specified illuminant condition (e.g. D50) across all tones in in a B&W print requires a flat curve parallel to the horizontal zero line for both a* and b*. Many inkjet papers on the market today vary from bright white to warm white color, and this range of media color typically plots between b* = -10 to +5. Also, many PK and MK inks don't always achieve a perfect b*=0 on all media. Hence, the a* and b* curves must also bend to accommodate printing system realities, but gentle gradual bending is visually better than lots of bumps and dips. That said, one shouldn't get alarmed at + or - deviations less than or equal to approximately 1.0 because much of that is simple instrument and patch measuring repeatability. However, when you see rapid dips or bumps at 2.0 a* or b* difference over smalL L* difference on these plots as seen in the Epson Standard curve plot at the 45 L* tone, such dips start to become noticeable as unwanted "color ripple". Some people are more sensitive to these color variations in B&W prints than others, but ABW mode in these graphs shows it's handling the hue gradation across the tone range better than the Epson standard mode in this test. Note also that even ABW mode shows a relatively rapid change in b* value as shadow tones near L* minimum. This is where the Epson driver is switching over to PK or MK black ink and feathering out the other gray inks and colors. This would be a noticeable issue too, but the saving grace is that it's occuring at the lowest L* values in the print. The often quoted rule that humans can see delta E changes as small as 1.0 is a good general rule of thumb but it's not perfect. As tones get darker, our visual color discrmination gets poorer, so a 3 0r 4 unit discrepancy in the very darkest part of the print will generally not be likely seen as that dip 2.0 b* dip occuring at the 45L location in the Epson Standard graph. Lastly, that the hue of Silver Rag gradually moves from slight positive 2.0 b* value at media white point (i.e., it's a slightly warm colored paper) to a -2.0 value over the tone range and then back up again as dmax (l*min) is approached is providing an ever so subtle split tone effect for this ink on this paper with this Epson driver, but overall would be judged as a very neutral B&W print with no unwanted color ripple (except for possibly in the Epson Standard mode at the b* dip occurring at L45).
Hello Mark,
many thanks for your valuable contribution and the articulated comments, I think it is very useful and appreciated.
Adding another straight line to the plot for the 0-100 (45 degrees) ideal L* function is clearly possible, I have done it in the past, but then I decided to remove it in order to keep the graph more clean and easily readable.
The most puzzling aspect for me is the strange L* "bump" in the deep shadows visible in the gamma 2.2 group.
It is something that usually I don't get, and consider that the big part of my personal past test are done in Adobe RGB (gamma 2.2), so this is very strange.
From what I can see in this case it could seems very reasonable to argue that the ABW mode is best served from a sRGB gamma than a 2.2 gamma, even if I know, as previously stated, that this is not always the case for sure, and at least it was not the case in the vast majority of my personal test.
I don't know if the fact that, in this test, the Alan printed strip was not colorspace assigned (it was kept unmanaged) before printing it, could have something to do with this phenomenon.
Another curious observation is the clear difference in the a* shape between "Epson-std" and all the "ABW" modes. In ABW modes the a* is very neutral across L* range, in Epson std is a little bit shifted toward green (negative values).
The last thought is related to the b* negative "bump" you rightly pointed out, which is more clearly defined in "Epson std" but it's still present in the ABW modes, even if somewhat masked from the more smooth (and extended in the shadows) shape of the b* curve.
Now, if you take in account that the "Epson std" L* values in the shadows zone are by far the darkest of all the 6 set (including ABW-darkest), and if you notice that moving across the ABW modes in a dark increasing order (from LT to D3) the b* shape in the shadows zone tend to "shift" to the right and to reveal/define more the negative "bump", in my opinion the b* shape of "Epson std" is not so inconsistent from the ABW ones, if you extrapolate the observed b* "right shift" from ABW-D3 to Epson std in relation to the increased L* darkness of the shadows zone.
I don't know if I was able to well explain what I intend to explain in this latest thought or not, so please, if something is not clear, let me know.
However, given the scale difference between L* (0 100) and a*, b* (-5 +5) adopted, the L* deviations from linearity visible in the graphs are more noticeable in real prints than the a*, b* (tone neutrality) ones, in my opinion.
Thanks again.
Ciao :)
Andrea
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The graphs are interesting info about several different aspects. So I have a few comments.
First, I've used similar graphs a lot over the years in making QTR curves. It's the best info about
how well you are doing with the linearity for both tones and neutrality.
1) about the initial data and methods. I have to agree with I think Mark A. the Epson STD being done without
an ICC profile shows just the response of the the driver and really isn't a good comparison of what you should
get printing normally. The ABWs however are supposed to be tuned from the get-go so they are indicative
of what you will actually get. (I wonder about the ABW-D3 data in both cases because it seems to go to L=100
rather than paper white of about L=96, but not too big a deal). I am surprised at how cool the darks are (b=-2.5)
in all the ABW cases. I don't think you've mentioned the ABW paper that was selected in printing but it may
have different characteristics than the Silver Rag paper you actually used.
2) the difference shapes of the curves in the dark shadows illustrate the difference between the different embedded
profiles. AdobeRGB and Gamma 2.2 are true gamma curves -- pure exponentials. sRGB and Mac's special
Generic Gamma 2.2 are pretty close for most of the range but you can see they are pretty different in the very
darkest range. These two have the same tonal curve which is mathematically more complicated but suffice to say its
similar to gamma 2.2 until the dark shadows. If you look at the L values for a step in the dark range you'll see that
all compress the shadows a bit more than linear L values.
(aside: in QTR I made a special ICC profile that is exactly linear in L -- called QTR-GrayLab and QTR-RGBLab -- this
essentially makes K (or RGB) values line up directly with L values).
If you print in Photoshop with Printer Manages Color and ABW in driver what I believe the system does is convert
your data to sRGB before sending to the driver. So what you see in the two sets of data is this conversion of
AdobeRGB (or Gamma2.2) to sRGB (or Generic Gamma 2.2).
3) Mark mentioned the "perfect system for L* tone reproduction". Ideally a straight-line from L=0 to L=100 would be
the goal. But since neither pure black not pure white is achievable we need to connect L(dmax) to L(dmin) somehow.
The simple straight-line seems like the obvious compromise (and in fact this is what linearization in QTR curves does).
But as I discovered with help from others is that what's more important is that the prints that come out match the
screen better. You have to have the mid tones match -- in other words the ideal curve has to go through (50,50).
With the examples given here that happens pretty close because dmin and dmax of photo paper is very close to the
white and black. The L=4 to L=96 line does go through (50,50). But with matte paper the much lower dMax
illustrates this better. A L=16 to L=96 line would go through (50,56) -- resulting in a noticeably lighter print.
Scaling for various dMax's is where Black Point Compensation (BPC) came about. Adobe has a paper about it in all
the gory mathematical detail. Bottom line is you should scale in the Luminance Y values rather than Luminosity L values.
See http://www.brucelindbloom.com if you want more detail about the math.
This is the main reason for using the CM of the system to match L values from source file to L values of the print
in such a way to give the best perceptual match given dmax/dmin limitations.
Roy
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The graphs are interesting info about several different aspects. So I have a few comments.
First, I've used similar graphs a lot over the years in making QTR curves. It's the best info about
how well you are doing with the linearity for both tones and neutrality.
Hello Roy,
it's very nice to have your comments here,
many thanks for this.
As you perfectly know, the plot I do are nothing new, in fact they are only a slightly rearranged looking versions of the ones you still provide in text mode as output of your QTR-tool :)
1) about the initial data and methods. I have to agree with I think Mark A. the Epson STD being done without
an ICC profile shows just the response of the the driver and really isn't a good comparison of what you should
get printing normally. The ABWs however are supposed to be tuned from the get-go so they are indicative
of what you will actually get.
Maybe Alan (who made the test) could help to better clarify what exact settings were used in the labeled "Epson std" data set.
Assuming the strip was kept untagged and the ACPU set to no color management, what need to be confirmed is whether in the Epson driver panel,
under the "mode" menu it was selected "Epson std" or "Off (no color management)" before printing (they are mutually exclusive).
Only in the second case we could tell that the measured data are related to a raw fully unmanaged workflow, but labeling it as "Epson std" was confusing, if the case.
Having read "Epson std" as label in the provided data I have interpreted it as the above menu option was set to "Epson std" and not "Off (no color management)", but a final confirmation from Alan could be useful to finally clarify the issue.
(I wonder about the ABW-D3 data in both cases because it seems to go to L=100
rather than paper white of about L=96, but not too big a deal).
You are right, this is strange in fact, it seems that the 5-6 readings near L* 100 in the ABW-D3 data set are abnormally lifted, this is something I forgot to ask to Alan about, and I'm still not easily able to figure out how it could happens. In any case it affects only the ABW-D3 plots, so we can even decide to keep these plots out of our thoughts without big impact.
I am surprised at how cool the darks are (b=-2.5) in all the ABW cases. I don't think you've mentioned the ABW paper that was selected in printing but it may
have different characteristics than the Silver Rag paper you actually used.
I was surprised too, for this reason I have remarked that the results should be considered tied to the given printer/paper/settings combination.
Maybe Alan could specify what media setting was used, it could be nice to know.
2) the difference shapes of the curves in the dark shadows illustrate the difference between the different embedded
profiles. AdobeRGB and Gamma 2.2 are true gamma curves -- pure exponentials. sRGB and Mac's special
Generic Gamma 2.2 are pretty close for most of the range but you can see they are pretty different in the very
darkest range. These two have the same tonal curve which is mathematically more complicated but suffice to say its
similar to gamma 2.2 until the dark shadows. If you look at the L values for a step in the dark range you'll see that
all compress the shadows a bit more than linear L values.
(aside: in QTR I made a special ICC profile that is exactly linear in L -- called QTR-GrayLab and QTR-RGBLab -- this
essentially makes K (or RGB) values line up directly with L values).
If you print in Photoshop with Printer Manages Color and ABW in driver what I believe the system does is convert
your data to sRGB before sending to the driver. So what you see in the two sets of data is this conversion of
AdobeRGB (or Gamma2.2) to sRGB (or Generic Gamma 2.2).
During the development of my linearization tool I have written some math script in Octave, based on LindBloom and Adobe tech info, in order to precisely calculate the RGB to Lab (and inverse) transformations for different colorspaces (currently sRGB, Adobe RGB and ProPhoto RGB). I have exactly implemented the ideal 2.2 gamma curve, the sRGB gamma curve (with their linear part in the deep shadows and a 2.4 exponent) and even the Adobe adopted gamma slope limit of 32 used in all ACE engines conversions when pure gamma curves colorspaces are involved.
I perfectly know that you are well aware of all of this stuff :)
I have written something regarding these arguments in my linearization thread here (Reply #18):
http://www.luminous-landscape.com/forum/index.php?topic=78142.0
That said, I tend to agree with you regarding the fact that the shape of the extra dark zone in the gamma 2.2 plots is probably the result of an untagged K strip, being plotted as a gamma 2.2 L* x axis, but being printed assuming to be in sRGB-gamma format from the Epson driver (not only in ABW but even in the so labeled "Epson std" mode).
This was the reason why I decided to plot again all the data using a sRGB-gamma conversion for L* x axis.
What I find interesting is that if this is true, this could be considered a big proof of the fact that by default Epson driver expect all the inages to be encoded in sRGB and this is valid for ABW mode too.
Since there was a long time debate on the net if this was the case or not, with different opinions, and due to the fact that in my (limited) test I rarely, if ever, have seen this effect in my gamma 2.2 (Adobe RGB) assigned strips, I was one of the people starting to believe that the default expectations of Epson driver was gamma 2.2.
Now I'm much less sure, and it could really be that Epson driver, as you correctly point out (and matching Eric Chan opinion for example), by default, is expecting a sRGB encoded image in all their modes (ABW included).
3) Mark mentioned the "perfect system for L* tone reproduction". Ideally a straight-line from L=0 to L=100 would be
the goal. But since neither pure black not pure white is achievable we need to connect L(dmax) to L(dmin) somehow.
The simple straight-line seems like the obvious compromise (and in fact this is what linearization in QTR curves does).
But as I discovered with help from others is that what's more important is that the prints that come out match the
screen better. You have to have the mid tones match -- in other words the ideal curve has to go through (50,50).
With the examples given here that happens pretty close because dmin and dmax of photo paper is very close to the
white and black. The L=4 to L=96 line does go through (50,50). But with matte paper the much lower dMax
illustrates this better. A L=16 to L=96 line would go through (50,56) -- resulting in a noticeably lighter print.
I agree with you, this is something we have already covered in my Linearization thread.
Currently my approach is to match the linear line between real ink black and paper white readings as general target because I considered it a good starting point for my early development.
It could be absolutely possible to implement a second options, by adopting an "S" shape target, instead of the pure line, still anchored to real black and white readings, which could mimic the ideal 45 degree 0-100 L* linear in the midtones zone with good match, at the expense of shadows and highlights compression.
As you rightly highlight this "S" target could produce better perceptive results in matte papers more suffering from limited Dmax. In this case the shadows compression should be carefully monitored to avoid excessive "crushing" potentially occurring, in my opinion.
Scaling for various dMax's is where Black Point Compensation (BPC) came about. Adobe has a paper about it in all
the gory mathematical detail. Bottom line is you should scale in the Luminance Y values rather than Luminosity L values.
See http://www.brucelindbloom.com if you want more detail about the math.
This is the main reason for using the CM of the system to match L values from source file to L values of the print
in such a way to give the best perceptual match given dmax/dmin limitations.
I agree with you, and, as already told, I am often using the wonderful Bruce website as one of my most important technical information source.
I will look for the Adobe paper you mentioned for sure.
Many thanks again for sharing you precious thoughts, it is very appreciated.
Ciao :)
Andrea
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To clarify things a bit, here are my settings for the print tests that I did. All prints were done with the Adobe Color Print Utility so that I could send untagged images through to the Epson driver. The paper setting is 'Ultra Premium Photo Paper Luster' for Museo Silver Rag with a platen gap setting of 4 (I have found that this is the best paper setting for this paper). For the "Epson Standard" data (probably a bad name), this was printed using 'No Color Management.' I will be printing out a patch strip using color management and a high quality profile that I created with ArgyllCMS that I use for normal printing. This profile includes a 51 step B/W patch set (maybe over kill but who knows). I should have the data over to Andrea as soon as the patch set has dried down sufficiently.
Alan
-
Assuming the strip was kept untagged and the ACPU set to no color management, what need to be confirmed is whether in the Epson driver panel,
under the "mode" menu it was selected "Epson std" or "Off (no color management)" before printing (they are mutually exclusive).
If I recall correctly, Adobe's rationale for providing the ACPU (Adobe color print utility) was to circumvent many problems people were having particularly on new Macs when trying to print untagged profiling targets. I know Alan is on a PC, so perhaps he can confirm this ACPU behavior on his OS, but at least on my MACs running OS10.8, ACPU forces the NCA mode automatically in the Epson driver (i.e., choices are grayed out on the menu) hence I concluded that the graph labeled Epson standard must be Epson NCA since Alan said he used ACPU to print the target.
-
Just a thought. Mark McCormicks's comment on the different choices in Epson ABW and corresponding deflections from the L line makes me wonder whether for light levels like 50 Lux in musea any adaption on the curves is adequate enough for the task. It would not surprise me if less than 255 steps in a greyscale image may improve the representation of an image then. One way or another curves have to compress tone ranges within a given dynamic range when they open up other parts and the eyes are less discriminating at that light level.
More the opposite of a wide dynamic range, lots of light and the possibility that 16 bit printing improved the image compared to 8 bit.
On the probably required sRGB assigned input on Epson ABW mode: the HP Z3100/3200 PCL3 driver B&W mode has a choice between sRGB and AdobeRGB. The rest is the same, HP recommends driver color management too then. For the Epson it is interesting then that there is no equivalent greyscale gamma choice to assign that resembles the sRGB curve. I do not expect a conversion happens between color spaces and/or gammas assigned. The driver expects sRGB and uses media preset specific LUTs to create the tone range.
--
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2012, 500+ inkjet media white spectral plots.
-
Ok,
thanks for all the clarifications,
now we know that the Alan "Epson std" labeled data set should be interpreted as "no color managed".
I don't know/use ACPU so this was not immediate for me.
Please, correct me if I'm wrong, but, from the printed results point of view, this should be the same as setting "printer manages color" in the PS print panel and "Off (no color management)" in the Epson driver, right?
Alan, do you have an explanation regarding what Roy pointed out for the strange higher values of the white L* values of the ABW-D3 data set? Do you think it could be a measurement error?
Let me know when the new ICC data are ready, I will put it on graph.
Ciao :)
Andrea
-
On the probably required sRGB assigned input on Epson ABW mode: the HP Z3100/3200 PCL3 driver B&W mode has a choice between sRGB and AdobeRGB. The rest is the same, HP recommends driver color management too then. For the Epson it is interesting then that there is no equivalent greyscale gamma choice to assign that resembles the sRGB curve. I do not expect a conversion happens between color spaces and/or gammas assigned. The driver expects sRGB and uses media preset specific LUTs to create the tone range.
Hello Ernst,
having the possibility in the HP B&W mode driver to chose between 2.2 gamma and sRGB gamma as the one expected to be present in the source image is nice.
This is something Epson could "copy & paste" for ABW :)
This lead to an important consideration in my opinion:
we don't know exactly whether ABW expect sRGB-gamma or 2.2-gamma. I was thinking the Epson ABW choice was for 2.2-gamma but probably it is sRGB-gamma.
In any case it is a fixed choice, so it could not be optimal for both the cases, and is affected from media settings too.
This means that the common convincement that "ABW provides better linearity", is a little bit dangerous and could lead to some noticeable printed deviations if blindly accepted without control, as we have seen.
In order to get out the best from plain ABW, printing and measuring a simple B&W test strip assigned to the desired colorspace and with given paper/printer/setting, for the two most common "normal" and "dark" settings, for example, could be very important at least to avoid big deviations and choose the better starting point.
We know that the results will be never optimal and may vary case to case, but at least we will have the information regarding how the still present non linearity is distributed across the L* range.
There could be lucky combinations, like my showed R3000+FibreSilk+ABW-dark in AdobeRGB, that are quite good out of the box, but we know that there could be far less optimal combination for sure.
To reach a full optimization (or to correct not satisfactory results that none of the preset can accommodate with a less lucky printer/paper/setting) the use of a correction profile like the one created by my beta-linearization tool (or by QTR with the needed workarounds) or, at least, a simple manual curve L* adjustment more or less empiric, is the only way and could greatly improve the final results.
It is maybe an extra-step in the workflow, I know, but given all the efforts and the level of scrutiny we invest in these activities it could be worth.
Ciao :)
Andrea
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Please, correct me if I'm wrong, but, from the printed results point of view, this should be the same as setting "printer manages color" in the PS print panel and "Off (no color management)" in the Epson driver, right?
Alan, do you have an explanation regarding what Roy pointed out for the strange higher values of the white L* values of the ABW-D3 data set? Do you think it could be a measurement error?
Let me know when the new ICC data are ready, I will put it on graph.
Ciao :)
Andrea
Correct about the driver settings. I will re-measure the ABW-D3 data set to make sure the value is correct. Just printed the ICC profiled patches and will read these later today after they have had a chance to dry down.
alan
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Andrea,
Thanks for the link to the linearization thread -- I had not read that before.
I see now that you've gone through all the math of color spaces etc.
My main comment on the linearization issue is I don't think that the straight-line is the best approximation
for the best perceptual match. But neither is the S-curve concept. The white end of the range
behaves (perceptually) very well, so a straight-line is fine for that end -- in fact simple luminance
scaling is built into the whole ICC profile concept. Only the dark end is problematic and not
addressed in the ICC -- which brought up Adobe's BPC algorithms. So the perceptual curve needs
to compress the shadows, make the mid tones stay in the same place, and the highlight go
straight to the dmin value. You can look at my generic ICCs Gray Matte Paper and Gray Photo Paper
in the ColorSync Utility. See the xTRC tag for the graphs -- this are not exactly the same as your
graphs since one of the axes is K values not both L values. So an L=50 gets converted into the K
value that produces L=50 in the driver (i.e. print). Anyway you can see the shape of the curves.
I guess one could debate whether this is the "ideal" transformation but it is the BPC algorithm and
does seem to produce a reasonably good match visually.
See: http://www.color.org/AdobeBPC.pdf
There's a lot of hard to decipher stuff in this but the bottom line is scale in Luminance Y -- the
very last section 7.3 step 3.
----------
The other issue is the AdobeRGB vs sRGB for Mac drivers. With Apple's Cocoa API
the idea was to always manage the color with ColorSync. So the default was to always convert
image output to a standard profile and let the driver handle anything special. This works great for
displays and virtually all the screen stuff in OSX is nicely color managed.
Up through Leopard 10.5 Generic RGB (a gamma 1.8 profile) was the "standard" profile for Mac print drivers.
After that (Snow Leopard) Apple decided that sRGB (close to a gamma 2.2) would be the standard.
As a driver writer you can actually select which one you want but default of sRGB is the norm.
The Epson driver lets you choose this if Printer Manages Color is on, and Color Matching is set
to Epson Color Controls. This all makes third party papers and custom ICCs problematic -- its
just not geared to the idea very well. But over the last few versions of OSX, CS, Epson, they
have managed to make a special program ACPU, a Photoshop Manages Color option, hidden flags
in the Print settings, and Epson driver NoCM option (forced) to allow custom ICCs for color.
B&W is a bit strained in this though -- ACPU doesn't work, the hidden flag doesn't work, and
the NoCM is forced/ABW disabled. Apple also created a new profile called Generic Gamma 2.2 (horrible
name since its not a gamma function) that mimics the shape of the sRGB profile but in grayscale.
Looks like Epson has matched the sRGB for ABW river -- but it would be interesting to see what
they do with matte papers -- straight-line, compressed shadows.
Roy
-
My main comment on the linearization issue is I don't think that the straight-line is the best approximation
for the best perceptual match. But neither is the S-curve concept. The white end of the range
behaves (perceptually) very well, so a straight-line is fine for that end -- in fact simple luminance
scaling is built into the whole ICC profile concept. Only the dark end is problematic and not
addressed in the ICC -- which brought up Adobe's BPC algorithms. So the perceptual curve needs
to compress the shadows, make the mid tones stay in the same place, and the highlight go
straight to the dmin value. You can look at my generic ICCs Gray Matte Paper and Gray Photo Paper
in the ColorSync Utility. See the xTRC tag for the graphs -- this are not exactly the same as your
graphs since one of the axes is K values not both L values. So an L=50 gets converted into the K
value that produces L=50 in the driver (i.e. print). Anyway you can see the shape of the curves.
I guess one could debate whether this is the "ideal" transformation but it is the BPC algorithm and
does seem to produce a reasonably good match visually.
See: http://www.color.org/AdobeBPC.pdf
There's a lot of hard to decipher stuff in this but the bottom line is scale in Luminance Y -- the
very last section 7.3 step 3.
Hello Roy,
many thanks for your explanations and for the direct link to the Adobe doc.
I have looked at it and it was interesting.
I know that the linear approach is only one of the possible choices,
in my case, it was only the simplest and logical to start with,
and even if not perfect for all the reasons already pointed out, the results I got were highly better than in absence of it, at least in my personal opinion.
Nothing stop the possibility to develop/try further different targets in the future, if desired.
I find interesting your idea of an "asymmetric" target, if you let me call it so. :)
It is very interesting even the solution to make two different general target for Matte and Photo papers, in order to compensate the different characteristics.
As per what I can understand, the resulting shapes are not casually similar to what I consider "slightly compressed in the shadows and overall a little bit dark" that are very common to see in my first-pass strip test.
The funny thing is that, usually, I compensate it when I build a linearization curve based on the straight line target. :)
I'm on PC so I don't know ColorSync, I have tried to dump the grayTRC values and to plot the numbers as they are inside your Matte and Photo paper ICC.
I have attached the graph because I think it could be useful, please, feel free to add any comment if you like.
The other issue is the AdobeRGB vs sRGB for Mac drivers. With Apple's Cocoa API
the idea was to always manage the color with ColorSync. So the default was to always convert
image output to a standard profile and let the driver handle anything special. This works great for
displays and virtually all the screen stuff in OSX is nicely color managed.
Up through Leopard 10.5 Generic RGB (a gamma 1.8 profile) was the "standard" profile for Mac print drivers.
After that (Snow Leopard) Apple decided that sRGB (close to a gamma 2.2) would be the standard.
As a driver writer you can actually select which one you want but default of sRGB is the norm.
The Epson driver lets you choose this if Printer Manages Color is on, and Color Matching is set
to Epson Color Controls. This all makes third party papers and custom ICCs problematic -- its
just not geared to the idea very well. But over the last few versions of OSX, CS, Epson, they
have managed to make a special program ACPU, a Photoshop Manages Color option, hidden flags
in the Print settings, and Epson driver NoCM option (forced) to allow custom ICCs for color.
B&W is a bit strained in this though -- ACPU doesn't work, the hidden flag doesn't work, and
the NoCM is forced/ABW disabled. Apple also created a new profile called Generic Gamma 2.2 (horrible
name since its not a gamma function) that mimics the shape of the sRGB profile but in grayscale.
Looks like Epson has matched the sRGB for ABW river -- but it would be interesting to see what
they do with matte papers -- straight-line, compressed shadows.
I cannot say it for sure, but given the not changeable sRGB-like companding curve adoption we have discussed, I doubt Epson implemented in ABW an internal different general target for Matte and Photo papers as you have done. Obviously there are some differences in the various media settings, but probably the general concept/target behind it is the same (but maybe I'm wrong here).
Thanks again.
Ciao :)
Andrea
-
...
I find interesting your idea of an "asymmetric" target, if you let me call it so. :)
It is very interesting even the solution to make two different general target for Matte and Photo papers, in order to compensate the different characteristics.
As per what I can understand, the resulting shapes are not casually similar to what I consider "slightly compressed in the shadows and overall a little bit dark" that are very common to see in my first-pass strip test.
The funny thing is that, usually, I compensate it when I build a linearization curve based on the straight line target. :)
I'm on PC so I don't know ColorSync, I have tried to dump the grayTRC values and to plot the numbers as they are inside your Matte and Photo paper ICC.
I have attached the graph because I think it could be useful, please, feel free to add any comment if you like.
I cannot say it for sure, but given the not changeable sRGB-like companding curve adoption we have discussed, I doubt Epson implemented in ABW an internal different general target for Matte and Photo papers as you have done. Obviously there are some differences in the various media settings, but probably the general concept/target behind it is the same (but maybe I'm wrong here).
Thanks again.
Ciao :)
Andrea
Hi Andrea,
I'm not sure why you make a point of "asymmetric" -- that's given. Any line between dMax L=16 and dMin L=96 is
asymmetric - since the end points are. And every different dMax would yield a different curve/target for any system.
My only point is that a straight-line in L-space isn't as good visually as a straight-line in Y-space. You probably
can't see the difference with photo paper because the dMax is so dark. But with matte paper it is noticeable.
Maybe the graphs (which you did plot correctly) are misleading. They just show what you get for a
correction curve given a simple straight-line Y-space mapping for two difference dMax values.
Overall the effect is taking into account the loss of dMax mostly in the shadows (compressing) rather than
over the whole range.
Roy
-
I'm not sure why you make a point of "asymmetric" -- that's given. Any line between dMax L=16 and dMin L=96 is
asymmetric - since the end points are. And every different dMax would yield a different curve/target for any system.
Hello Roy,
Sorry for the misleading naming, the word "asymmetric" I (somewhat improperly) used was a concept to be intended in the sense that the shadows are slightly compressed but, as you point out, the highlights should not and are going to Dmin directly.
So, using the same philosophy, an "S" shape could be considered symmetric (as concept) because the shadows and highlights are both compressed in the same way (with the obvious caveat of being anchored to black and white paper values, which are usually not equally spaced from 0 or from 100, but this was not the point). Similarly, even a straight line could be considered symmetric, as philosophy, in the sense that there is no conceptual different treatment between shadows and highlights.
In pure math term the word is not appropriate as you pointed out.
My only point is that a straight-line in L-space isn't as good visually as a straight-line in Y-space. You probably
can't see the difference with photo paper because the dMax is so dark. But with matte paper it is noticeable.
Maybe the graphs (which you did plot correctly) are misleading. They just show what you get for a
correction curve given a simple straight-line Y-space mapping for two difference dMax values.
Yes thanks, I had understood the point, it could be interesting to evaluate the effect of a Y straight line as target instead of the L* one,
in special way for the more Dmax limited Matte papers, I will keep it in consideration.
Overall the effect is taking into account the loss of dMax mostly in the shadows (compressing) rather than
over the whole range.
Yes, that was exactly the reason why I tagged this approach as "asymmetric", as previously explained, so not in negative mean, but just because of the conceptual idea behind it.
Many thanks for all the useful opinion you share here,
it is really appreciated.
Ciao :)
Andrea
-
Roy, Andrea,
Is there any chance you could construct a kind of appearance model into the curve creation that would address the display lighting level in combination with the available dynamic range? Say choices for bare display, framed behind ordinary framing glass and 120 Lux, 450 Lux, 2000 Lux? Skip the 50 Lux of musea I would say. There is not much published on display light levels and B&W tone ranges. I also did a search on the Zone System and display conditions but nothing to build on is found then. A lot more on the image creation phase and different light levels in the scene.
Interesting PDF is this one but also for the input side:
Perceptually Based Tone Mapping for Low-Light Conditions, Adam Garnet Kirk
In ICC profile creation there are choices for different color temperatures in viewing conditions but normally not for lighting levels. Some comments on that could be made for B&W prints too, the use of OBA papers and different light levels/color temperatures for example.
In the Colorsync list in a discussion called "Colormetric Accuracy in the Field" some examples were quoted of the huge difference between the viewing light in the creation phase of prints/art and the light at display. Stanley Smith and Graeme Gill comments.
--
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2012, 500+ inkjet media white spectral plots.
-
To clarify things a bit, here are my settings for the print tests that I did. All prints were done with the Adobe Color Print Utility so that I could send untagged images through to the Epson driver. The paper setting is 'Ultra Premium Photo Paper Luster' for Museo Silver Rag with a platen gap setting of 4 (I have found that this is the best paper setting for this paper). For the "Epson Standard" data (probably a bad name), this was printed using 'No Color Management.' I will be printing out a patch strip using color management and a high quality profile that I created with ArgyllCMS that I use for normal printing. This profile includes a 51 step B/W patch set (maybe over kill but who knows). I should have the data over to Andrea as soon as the patch set has dried down sufficiently.
Thanks Alan for sending me the new data related to the Argyll ICC measurements,
you have not specified which is the expected colorspace of the source images during the profile creation (i.e. if you used -S sRGB or -S AdobeRGB in Argyll colprof),
so I have a similar dilemma as the previous data set here, regarding how to interpret the K values to transform it in L* values for x axis reference.
Looking to the graph I could dare to guess you used AdobeRGB in Argyll colprof, but please correct me if this is not the case.
In the meantime I have done the graphs for both AdobeRGB (2.2 gamma) and sRGB (sRGB gamma).
You can find it in attachment for further evaluation.
After the useful Mark and Roy comments and for additional convenience I have provided both the plot twice,
they are the same in fact, only with a different dotted line reference:
"LIN dotted ref" means that the dotted straight line is my usual one (connecting ink black to paper white)
"ABS dotted ref" means that the dotted straight line is the ideal L* ramp from 0 to 100.
Regarding the L* linearity:
it is visible that the 2.2-gamma plot, even if not perfectly matching my LIN dotted target, it is less dark (compressed) than the gamma-sRGB one in the shadows.
In addition, comparing the same two gamma plots to the ABS dotted target we can spot the kind of shape Mark and Roy have well explained.
For this reason I guess that if you use this ICC in AdobeRGB images you should be probably satisfied (at least regarding the tone contrast, I cannot say nothing regarding the color gamut). This is something you was not able to achieve in ABW for 2.2-gamma, as we have previously seen.
Regarding the gray neutrality: we can say that Argyll has done an excellent job here, the gray tone is perfectly neutral and smoothly rolling off to paper white tone. this result is superior to the ABW one, and I think that this could be even visible in the real print maybe.
My final thought is that, assuming your work is in Adobe RGB, for B&W print you are overall best served from this ICC (using the same settings you have used here obviously): you get a better L* shape and much better gray neutrality than in ABW. You loose only something in Dmax, but this is a known issue.
I hope this was useful,
let me know your opinion.
Ciao :)
Andrea
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Thanks for plotting this! To answer your question I used AdobeRGB for the color space. I have found that this profile does give excellent B/W prints with the only drawback that the Dmax is not quite as good as with the Epson ABW driver. Of course as Mark has noted this may not be too important as there is a question whether it would be visibly perceptible. It looks like this is a good vindication of my use of the 51 step B/W patch set when I make the profiles. Now I'm going to have to go back and make some test prints under all these different conditions to look at how shadow detail is handled!!!! ;D
-
Is there any chance you could construct a kind of appearance model into the curve creation that would address the display lighting level in combination with the available dynamic range? Say choices for bare display, framed behind ordinary framing glass and 120 Lux, 450 Lux, 2000 Lux? Skip the 50 Lux of musea I would say. There is not much published on display light levels and B&W tone ranges. I also did a search on the Zone System and display conditions but nothing to build on is found then. A lot more on the image creation phase and different light levels in the scene.
Interesting PDF is this one but also for the input side:
Perceptually Based Tone Mapping for Low-Light Conditions, Adam Garnet Kirk
In ICC profile creation there are choices for different color temperatures in viewing conditions but normally not for lighting levels. Some comments on that could be made for B&W prints too, the use of OBA papers and different light levels/color temperatures for example.
In the Colorsync list in a discussion called "Colormetric Accuracy in the Field" some examples were quoted of the huge difference between the viewing light in the creation phase of prints/art and the light at display. Stanley Smith and Graeme Gill comments.
Hello Ernst,
thanks for raising this complex argument and for pointing out to this technical publication, I will look at it because it seems very interesting, even if I don't know if it could be practical useful in real terms.
Frankly, I think you are overestimating my knowledge :)
The only answer I can try to formulate at the moment is that, at least in principle, it would/could be possible to compensate for every kind of behavior, within the limits set by a Lab curve-styled correction, if we know how to model/represent these different conditions you are interested in.
In simple terms, if I know that in a given light condition the perceived tone curve is shapeable in a given way, we can try to build a compensation profile based on this shape in order to print the image specifically for that kind of condition.
This could be more or less complex to realize, maybe, but, in theory, I guess it should be technically feasible.
The culprit is "how" to model each light condition in this way?
Honestly, at the moment I completely ignore how to do it and where, if any, these information can be found.
In addition, as you know, these kind of strictly targeted corrections have the disadvantage to be maybe good in the theorized conditions, but at the risk to become worse if something change, so the real usefulness is in perfectly controlled constant environmental condition only.
This mean that if you print an image for a given light condition (exhibition) and during their life time this picture is then moved/sold exposed in different conditions, it could look very bad.
This is something to keep in consideration, because maybe a more general-purpose conservative approach, even if never optimized for all conditions, in long terms is more appropriate.
In any case this is an intriguing argument indeed,
I'm sure that there is more expert people here who could add very valuable opinions on this regard and this will really appreciated.
Ciao :)
Andrea
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Thanks for plotting this! To answer your question I used AdobeRGB for the color space. I have found that this profile does give excellent B/W prints with the only drawback that the Dmax is not quite as good as with the Epson ABW driver. Of course as Mark has noted this may not be too important as there is a question whether it would be visibly perceptible. It looks like this is a good vindication of my use of the 51 step B/W patch set when I make the profiles. Now I'm going to have to go back and make some test prints under all these different conditions to look at how shadow detail is handled!!!! ;D
Glad you found it useful,
please, keep in consideration that if you print the same AdobeRGB image with the ICC and with ABW-D1 (or D2) it could be that, by comparing it with the ICC one, depending on the kind of image and light conditions, in the deep shadows you could get a slight apparent advantage in the ABW printed images, due to the showed slight "bump" present in that zone, derived from the sRGB-gamma expectation of the ABW driver.
Let we know your findings.
Ciao :)
Andrea
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Frankly, I think you are overestimating my knowledge :)
In addition, as you know, these kind of strictly targeted corrections have the disadvantage to be maybe good in the theorized conditions, but at the risk to become worse if something change, so the real usefulness is in perfectly controlled constant environmental condition only.
This mean that if you print an image for a given light condition (exhibition) and during their life time this picture is then moved/sold exposed in different conditions, it could look very bad.
This is something to keep in consideration, because maybe a more general-purpose conservative approach, even if never optimized for all conditions, in long terms is more appropriate.
Ciao :)
Andrea
You should not think that I could read that article but it gives an impression of the intentions :-)
There are good reasons to optimize a print for a specific display condition and that should happen at the last stage at printing time without affecting the "mother" file. A printer profile acts like that. Qimage's print filter too, which is another candidate for the job if the Qimage curves tool was not so clumsy. Describing the precise display condition in the selections will help, the light to darker settings in for example the ABW driver are too vague (Mark's explanation helps though) and I avoid similar choices in the HP drivers. The Lux numbers I quoted are estimations of average display conditions by Kodak, Wilhelm (ISO) and what is considered a level for color critical work. See the explanation of exposure levels in PDF files of Aardenburg-Imaging.
The choices will not replace print proofs for serious work but could offer a better starting point.
--
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2012, 500+ inkjet media white spectral plots.
-
In simple terms, if I know that in a given light condition the perceived tone curve is shapeable in a given way, we can try to build a compensation profile based on this shape in order to print the image specifically for that kind of condition.
This could be more or less complex to realize, maybe, but, in theory, I guess it should be technically feasible.
The culprit is "how" to model each light condition in this way?
Honestly, at the moment I completely ignore how to do it and where, if any, these information can be found.
In addition, as you know, these kind of strictly targeted corrections have the disadvantage to be maybe good in the theorized conditions, but at the risk to become worse if something change, so the real usefulness is in perfectly controlled constant environmental condition only.
This mean that if you print an image for a given light condition (exhibition) and during their life time this picture is then moved/sold exposed in different conditions, it could look very bad.
This is something to keep in consideration, because maybe a more general-purpose conservative approach, even if never optimized for all conditions, in long terms is more appropriate.
In any case this is an intriguing argument indeed,
I'm sure that there is more expert people here who could add very valuable opinions on this regard and this will really appreciated.
Ciao :)
Andrea
A subject near and dear to me. Over thirty years ago, my senior research thesis at Rochester Institute of Technology explored the complex issues of human brightness perception. I got into the subject somewhat by chance by asking a professor why color slide film (remember slides?) had to be processed to a much higher contrast level than reflection prints in order to look good when projected in a dark theater. That one question set me on a lifelong course of study in the subject of color and tone reproduction in prints and photographs and ultimately to print preservation because once a printmaker achieves his/her vision of a "perfect print" why wouldn't we want to preserve the artist's original intent as long as possible?
I sought out experts at Eastman Kodak which quickly led me to the work of Bartleson and Brenneman on lateral adaption, (which in turn ultimately explained my original question about slide projection in a dark theater). However, as Andrea and others have observed, it's generally a challenge to "bake" into any given image reproduction a custom tone curve aimpoint because the printmaker has little control on how the final print will be displayed. As a good summary for some of the fascinating human visual system complexities which color scientists are working on with regard to both color appearance models and image appearance models (image appearance being even more complex) take a look at this information: http://www.cis.rit.edu/fairchild/PDFs/AppearanceLec.pdf
If you'd like to see a practical demonstration of effect of surround brightness on image appearance, the monitor checker target I developed to validate monitor calibration has three layers that can be toggled on and off to add a light, middlegray, or dark field surrounding the calibration target. The instruction layer in the image file will help you figure out how to use this test target. Photoshop is needed to use it:
http://aardenburg-imaging.com/cgi-bin/mrk/_4878ZGxkLzBeMTAwMDAwMDAwMTIzNDU2Nzg5LyoyMTA=
Note in particular how the choice of the dark surround improves one's ability to observe shadow detail (the dark numbers going from L*= 0 to L* = 9 in the target). Zooming in closer to the letters, i.e, magnifiying them in one's area of view thus affecting viewing surround conditions again, can also be seen to have an impact on visual appearance. This means that even one's choice of final print size will have an affect on what tone curve and viewing conditions are optimal for any given image.
The Bartleson-Breneman adaptation effect is often used by museum lighting designers to compensate for low overall (e.g., 50 lux) lighting levels, for example. Allow the viewer time to adjust to a room that has very low light levels (less than 10 lux). Now train a focused spot illuminating just the print at 50 lux. It will appear much brighter and more luminuous than if one just set the whole room to 50 lux average even illumination on white walls. This is the Bartleson-Brenneman effect being used in practice to create superior display environment for valuable prints and paintings that require lower overall illumination levels for best preservation practices.
I mention all this as a practical/informative exercise that printmakers can try in their own studios, the goal, IMHO, being to produce prints that look better under a wider range of real world lighting conditions and tailored to suit one's personal tastes. I haven't done an exhaustive technical study of the subject, but my sense is that modern ICC profiles and the CIELAB color model are designed to produce optimal color and tone viewing when print illumination levels approach 2500 lux on white or gray walls lit with broad and even lighting. One can drop to about 500 lux and still find the reproduction quite good. But as one goes down from there, especially as one gets below 200 lux for middle-aged people with reduced ability to discriminate color in low lighting levels, then compensation with a lighter tone curve aim point and/or some attention being paid to viewing surround conditions, overall print size, and even mat border size/color starts to come into play for a better print viewing experience.
regards,
Mark
http://www.aardenburg-imaging.com