Luminous Landscape Forum
Raw & Post Processing, Printing => Digital Black & White => Topic started by: Doug Gray on September 25, 2019, 12:49:27 pm
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Is there some trick for being able to use custom B&W profiles in Photoshop for Canon printers? Both my Pro1000 and 9500II disable selecting profiles as well as "Photoshop Manages" when I have the B&W setting checked in the driver.
OTOH, Epson works fine with ABW and lets me use custom B&W profiles and the results are excellent with measured L* values being very close.
There's a workaround using convert to custom profile then assigning the resulting device RGB values to sRGB which also works fine with any printer but is not exactly intuitive.
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that's also a question I'm interested since my Epson 3880 died and I replaced it with a Canon Pro-1000. I created B/W profiles for the papers I used with the Epson ABW driver using the QTR tool and the nice thing is that you could 'soft proof' with those profiles. Of course this only works with WinOS as Apple broke that approach some years ago. That was a real benefit as you could tweak images reliably without wasting paper.
I've not printed B/W prints using the Canon driver setting and I guess I need to experiment with it. Canon offers a plug-in for PS & LR that I have not tried but I think it prints B/W to sRGB as you note.
EDIT: I checked Keith Cooper's review of the Pro-1000 and he talks about the use of QTR profiles with this printer but doesn't show any settings as to how to implement them: http://www.northlight-images.co.uk/canon-pro-1000-printer-review/#profiling
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Convert your RGB file to QTR – Gray Lab colour space. That allows softproofing in Lightroom.
Print QTR's 21-step grey wedges and measure them (a Datacolour Spyder will do) and drop the results into the QTR-Create-ICC droplet to linearise and to create a print profile.
I use that profile to print out of Lightroom with the printer set to monochrome.
There is quite a bit of info on this on Keith Cooper's website.
A quick Google search brought up this:
https://cameratico.com/guides/black-and-white-icc-profiles-and-soft-proofing/
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Convert your RGB file to QTR – Gray Lab colour space. That allows softproofing in Lightroom.
Print QTR's 21-step grey wedges and measure them (a Datacolour Spyder will do) and drop the results into the QTR-Create-ICC droplet to linearise and to create a print profile.
I use that profile to print out of Lightroom with the printer set to monochrome.
There is quite a bit of info on this on Keith Cooper's website.
A quick Google search brought up this:
https://cameratico.com/guides/black-and-white-icc-profiles-and-soft-proofing/
The 21 step chart in steps of L*:5 is not enough for the best B&W profiles when not using a RIP. I use either RGB steps of 5 or 1, which makes 52 or 256 neutral patches. The 52 patch set isn't quite as good as the 256 set. Especially if the printer doesn't produce patch Lab values consistently. The larger patch set, especially the 256 one, makes profiles based on more than the nearest patch or two so bad readings are usually smoothed out and reduce profile error.
I have a good program that lets me generate B&W profiles with either I1Profiler or Argyll'c colprof and, since they only use neutral patches, they produce more accurate L* than even very large color profiles printing B&W using standard color workflow. And it's great at soft proofing with one exception. The soft proof doesn't reflect tone, such as a Sepia tint. While perfect on the L*, it only displays pure neutrals.
I'm working on fixing that so the soft proof will show proper tints but it will only work on Rel. Col. and Perc. Abs. Col. is meaningless for B&W because it requires shift from paper white to actual neutral, an impossibility. However, the show paper color option should be possible for soft proofing.
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Hi Doug.
I'm not doing high end profiling. But even so, I would expect that a 21 patch chart would not be good enough.
However, I can't fault the results from the combination of QTR colour space and the basic 21 step chart.
The test prints look fine. Circular gradients show no sign of non-linearity. A 0-255 patch print shows separation between patches right down to zero (in good light) and up to 255.
I think an improved profile could well be achieved, but I don't think I would see an improvement in the actual prints themselves.
I'd be interested to get another opinion on this in regard to what people are actually seeing in their prints.
Also, since I have the printer set to monochrome the issue of softproofing for tint hasn't come up for me.
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Hi Doug.
I'm not doing high end profiling. But even so, I would expect that a 21 patch chart would not be good enough.
However, I can't fault the results from the combination of QTR colour space and the basic 21 step chart.
The test prints look fine. Circular gradients show no sign of non-linearity. A 0-255 patch print shows separation between patches right down to zero (in good light) and up to 255.
I think an improved profile could well be achieved, but I don't think I would see an improvement in the actual prints themselves.
I'd be interested to get another opinion on this in regard to what people are actually seeing in their prints.
Also, since I have the printer set to monochrome the issue of softproofing for tint hasn't come up for me.
David,
You might be surprised but I think your observations are entirely correct. 21 patches is enough to get reasonably accurate but more importantly, visually smooth results. An individual reading error of say, .5 to 1.0 dE is not usually enough to create a visible lack of smoothness in gradients for 21 steps. It's more of a problem when you have 30 to 40 steps. That's a kind of maximum sensitivity. Beyond that, anomalous readings start to decrease in their visual effect on a high, patch count profile. I use a strong, low pass filter with a width of about +-3 steps for the largest one (256 steps). This seems optimal in terms of accuracy and visual smoothness (not the same thing).
However, the differences aren't visible to me and I can only see differences looking at measured value accuracy. And lumpiness is far more visible than differences in absolute accuracy.
Much of my work is (was) specialized technical chart creation where accuracy was more important than smoothness but smoothness is the most critical for 99.9% of printing apps.
The printers I've looked at have low lumpiness in B&W mode. This isn't the case using color profiles and color printing workflow to print B&W. B&W mode is much better behaved.
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Thanks for the clarification Doug.
I'm somewhat relieved.
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I have a good program that lets me generate B&W profiles with either I1Profiler or Argyll'c colprof and, since they only use neutral patches, they produce more accurate L* than even very large color profiles printing B&W using standard color workflow. And it's great at soft proofing with one exception. The soft proof doesn't reflect tone, such as a Sepia tint. While perfect on the L*, it only displays pure neutrals.
Hi Doug,
How do you use Argyll to create B/W profiles? My understanding from Graeme is that it does not support this feature. I can set Argyll up to read B/W patch sets of various types but have been using the QTR script tool to create the profile. My routine is to use a 51 step gradient as opposed to 21.
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Hi Doug,
How do you use Argyll to create B/W profiles? My understanding from Graeme is that it does not support this feature. I can set Argyll up to read B/W patch sets of various types but have been using the QTR script tool to create the profile. My routine is to use a 51 step gradient as opposed to 21.
Argyll doesn't make B&W only profiles unlike QTR that does. But that doesn't prevent making standard "color" profiles that are used for B&W.
This is actually what Canon does with the Pro1000. They use the same color profiles (Limited to the Canon supplied ones - no custom allowed) but run the data through the B&W driver process.
When I first noticed that I thought Canon was just using the same driver but converting RGB to B&W. This isn't the case. Canon's B&W mode is completely different than the color mode and it makes, like Epson, very neutral prints with only small excursions in a* and b*. The deltaE between the two modes on a neutral ramp is as much as 10 due almost entirely to the a* and b* differences.
The L* delta varies about +- 2 between the two modes and averages under .8 which allows them to use their existing profiles for B&W.
Getting back to Argyll, B&W profiles can be considered a subset of color profiles but where the LUT values for a* and b* are 0 and the output's 3 channels, which will already be close to each other are treated as B&W by the driver. If, in fact, the LUTs produce the same output for B&W PCS Lab values, then the profile is effectively operating as a true black and white profile.
The problem is creating such a profile. Colprof and I1Profiler require RGB values and a color gamut. My solution is to provide them one by synthesizing Lab values that are not along the neutral axis in such a way that they intercept the B&W printer neutrals. This means printing and measuring a 256 RGB neutral patch set. Then the a* and b* of the measured Lab values are set to 0. Next, Lab values are synthesized by adding a grid and creating "colors" to fill out the needed, but unused in B&W, values. Then the data set is loaded by I1Profiler or Argyll's colprof and a profile is created.
And they make great B&W prints since the LUTs don't have to correct for a* and b* variations off 0. Much smoother and more accurate than making B&W using a full color workflow.
Now, if I could find some direct way to print using them w/o the workaround described in my first post.
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Argyll doesn't make B&W only profiles unlike QTR that does. But that doesn't prevent making standard "color" profiles that are used for B&W.
Now, if I could find some direct way to print using them w/o the workaround described in my first post.
Got it. Normally when I use Argyll to create standard profiles, I include a 51 step B/W patch set so that the profile can be used for monochrome printing through the normal print path. The results are good but probably could be tweaked a little better using a the dedicated Canon Pro-1000 B/W print option.
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Got it. Normally when I use Argyll to create standard profiles, I include a 51 step B/W patch set so that the profile can be used for monochrome printing through the normal print path. The results are good but probably could be tweaked a little better using a the dedicated Canon Pro-1000 B/W print option.
Quite a bit better actually, The B&W mode uses more neutrals and fewer CYM dots. The problem with printing B&W with standard color workflow is that profiles don't do that great a job getting rid of the a* b* excursions due to the added CYMs. Even large numbers (hundreds) of neutrals only brings the dE2000 errors down to about the same level as dE2000 on color patches. Synthesized B&W profiles using measured neutrals with added "colors" allows the profiles to track only L* and significantly reduces B&W dEL*s.
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Here's a plot of L* for 0 to 100 in steps of 1. Consists of 101 patches in 16 bit Tiff Lab printed and measured with an i1iSis XL 2.
How the profile was made:
My profile was made from 256 RGB neutrals then read with the i1iSis/I1Profiler and saved as a CGATs. This was then run through a program to zero a* and b* and add synthesized "colors" which produced an RGBLAB CGATs file suitable for I1Profiler profile creation or Argyll. I dropped this into the I1Profiler "measure" box then selected high quality for the profile.
How the Lab patches were printed:
The lab patch tif file was created from a CGATs Lab file with 101 patches from 0 to 100. This can be done with Patchtool though I used one of my MATLAB functions.
Printing with an Epson is simple as the profile can be selected using standard color management. However, printing with the Canon required the following workaround which produces the equivalent.
In Photoshop:
1. The 101 Lab tiff chart was converted to the B&W profile using edit->convert with Abs. Intent selected.
2. The image was then assigned to the Canon Pro1000 Platinum profile using edit->assign profile.
3. The image was then printed using Photoshop Manages selecting the Canon Pro1000 Platinum profile.
*steps 2 and 3 are called the "null trick" and is a workaround to print without color management. Since the image had been converted to device RGB space in step 1 we just need to print it with no further conversions. Using the same profile that the image is in does this. Photoshop sees they are the same profile and sees no further conversion is needed. This has always worked in Windows with all versions of Photoshop though recent versions stick up a warning and a link to their ACPU. Cancel the warning. This is an issue with iOS, not Windows.
If there was a way to get the profile to be listed in Photoshop's pull down print menu thee null-trick wouldn't be necessary and one could use standard color management techniques but there doesn't seem to be a way to do this so far.
The attached plot shows a "perfect" L* response in blue. It's just a straight line from 0 to 100. The red line is the actual measured L*. It shows a min L* of 2 and a max of 95 which are the printer/paper limits.
Ave error of L* measurements was .18, max: .38
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Doug,
Though it might be more complicated could you use the Argyll cctiff tool to embed the profile and then send the resulting tiff through the Canon B/W print path? Maybe you can soft proof using the profile to make sure it looks correct before embedding it.
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Doug,
Though it might be more complicated could you use the Argyll cctiff tool to embed the profile and then send the resulting tiff through the Canon B/W print path? Maybe you can soft proof using the profile to make sure it looks correct before embedding it.
First, a comment about soft proofing. Standard soft proofing works fine on the image (before it is converted to printer space) in exactly the same way QTR B&W profiles softproof. It's particularly good for checking deep shadow blocking where the paper's max black is lighter than what the image contains. BPC fixes that just as in regular printing but my preference is to use curves to adjust the image so the darkest aligns with the paper's profile. BPC just assumes the image has RGB 0,0,0 in it and aligns to that.
Steps 2 and 3 would still need to be done to print it from Photoshop. The same thing could be done for any normal color printing. Conversion intent and BPC are used to generate the exact same device RGB values that would be normally made with the same selections in the printer dialog.
Steps 2 and 3 are just a way to make Photoshop send the now converted RGB values unaltered to the printer. It doesn't matter which profile is actually assigned in step 2 as long as the same profile is selected in step 3. it also makes no difference which rendering intent is selected in step 3. The settings are ignored by Photoshop because the image is already in the same ICC profile colorspace as selected for printing. The settings only come into play when the images' working colorspace differs from the colorspace selected in the Photoshop printer dialog.
The workaround is a nuisance but simple enough.
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I'm finally getting around to using the B/W setting on the Pro1000. I do all my printing through LR rather than Photoshop because it's more intuitive to use. I checked the B/W option in the Canon print driver and in LR, the profile selection box is not grayed out so I'm able to select a profile. Does the printer ignore this profile? Right now I don't have any B/W only profiles so I'm using a regular profile that has a 51 step B/W patch set (I've used this profile to print out B/W images through the normal print pathway). It's almost impossible to tell the difference between the images. I also printed the same image out in the B/W mode and setting color management to "managed by the printer." I'll let the prints dry down over night and then take a long look. Since the Canon manual is pretty worthless (Epson was always clear about the driver settings and print application software), I'm wondering what the correct approach is. I suspect that it maybe let the printer manage things but it's really hard to tell the difference between prints right now.
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I'm finally getting around to using the B/W setting on the Pro1000. I do all my printing through LR rather than Photoshop because it's more intuitive to use. I checked the B/W option in the Canon print driver and in LR, the profile selection box is not grayed out so I'm able to select a profile. Does the printer ignore this profile? Right now I don't have any B/W only profiles so I'm using a regular profile that has a 51 step B/W patch set (I've used this profile to print out B/W images through the normal print pathway). It's almost impossible to tell the difference between the images. I also printed the same image out in the B/W mode and setting color management to "managed by the printer." I'll let the prints dry down over night and then take a long look. Since the Canon manual is pretty worthless (Epson was always clear about the driver settings and print application software), I'm wondering what the correct approach is. I suspect that it maybe let the printer manage things but it's really hard to tell the difference between prints right now.
Interesting. Seems to show all the profiles in Lightroom but Photoshop limits profiles to Canon's. Since LR forces BPC with Rel. Col. and doesn't have Abs., it's not too useful. I prefer, on photos, to adjust the L* low end with curves. And I use Abs. for various, non photo, printing. Can't give that up.
Because of BPC, there should be no difference softproofing a B&W profile in LR and just the monitor. The only value in a custom profile is printing accuracy and printer/printer consistency.
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Interesting. Seems to show all the profiles in Lightroom but Photoshop limits profiles to Canon's. Since LR forces BPC with Rel. Col. and doesn't have Abs., it's not too useful. I prefer, on photos, to adjust the L* low end with curves. And I use Abs. for various, non photo, printing. Can't give that up.
Because of BPC, there should be no difference softproofing a B&W profile in LR and just the monitor. The only value in a custom profile is printing accuracy and printer/printer consistency.
After drying overnight, all three images on letter paper look exactly the same. Maybe some nuances might show up if I was doing a larger print, I don't know. I also need to do a B/W profile or two to see if that makes a difference or not. According to Eric Chan's original directions for the Epson 3800 printer he noted that the profiles can be used for soft proofing so that you can make adjustments to reduce blocking of shadows, etc.
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After drying overnight, all three images on letter paper look exactly the same. Maybe some nuances might show up if I was doing a larger print, I don't know. I also need to do a B/W profile or two to see if that makes a difference or not. According to Eric Chan's original directions for the Epson 3800 printer he noted that the profiles can be used for soft proofing so that you can make adjustments to reduce blocking of shadows, etc.
Per Chan, that's exactly what I use B&W profiles for. Checking for blocking, which is more of a problem on matte using Photoshop. There should be no blocking with LR since BPC is always enabled. Profiles work great in Photoshop too (both printing as well as soft proofing) on my Epson 9800 and Photoshop lets me squeeze more out of the dark end with curves while soft proofing rather than using BPC which is a hammer. BPC sets L*=0 at paper L* min. so image L* 10 is about paper L* min. plus 3 to 4.
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I'm working on bringing real soft proofing to "B&W" profiles. By this I mean proofing that shows the actual tint of a print when soft proofing but doesn't alter RGB values sent to the device. The goal is to let one adjust the tone of a B&W print with the driver sliders for various looks an have it properly show in soft proof.
The general approach is to synthesize two profiles from the same B&W printed chart measurements. One which has the correct AtoB1 table (used by soft proof) and one which has the correct BtoA1, AtoB0 tables which translate neutrals to corrected device neutrals. Then the AtoB1 table from the first is copied into the AtoB1 tables of the second. This results in one profile that can be used for both printing and soft proofing and will accurately display whatever print tone has been set in the driver.
Argyll and I1Profiler can be used to make the necessary "B&W" profiles and the same program used to create and process B&W patch sets can be used to make the final profile.
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I'm working on bringing real soft proofing to "B&W" profiles. By this I mean proofing that shows the actual tint of a print when soft proofing but doesn't alter RGB values sent to the device. The goal is to let one adjust the tone of a B&W print with the driver sliders for various looks an have it properly show in soft proof.
The general approach is to synthesize two profiles from the same B&W printed chart measurements. One which has the correct AtoB1 table (used by soft proof) and one which has the correct BtoA1, AtoB0 tables which translate neutrals to corrected device neutrals. Then the AtoB1 table from the first is copied into the AtoB1 tables of the second. This results in one profile that can be used for both printing and soft proofing and will accurately display whatever print tone has been set in the driver.
Argyll and I1Profiler can be used to make the necessary "B&W" profiles and the same program used to create and process B&W patch sets can be used to make the final profile.
I have coded and verified that this approach works for creating a profile that can be used for both printing and soft proofing B&W and it correctly soft proofs both tinted and untinted images. It works with both Argyll and I1Profiler. I am cleaning up the code and will post it to github in a day or two. The code is in pure C++ with no external libraries and can be compiled and run on iOS, Linux, and Windows systems. I will also post a link to a Windows executable as well as a Argyll profile that demonstrates soft proofing and printing based on my Pro1000 B&W mode.
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I have coded and verified that this approach works for creating a profile that can be used for both printing and soft proofing B&W and it correctly soft proofs both tinted and untinted images. It works with both Argyll and I1Profiler. I am cleaning up the code and will post it to github in a day or two. The code is in pure C++ with no external libraries and can be compiled and run on iOS, Linux, and Windows systems. I will also post a link to a Windows executable as well as a Argyll profile that demonstrates soft proofing and printing based on my Pro1000 B&W mode.
Can you create an Argyll 'ti1' file for the synthetic data set that users can create patch sets for different papers? I've tried adapting CGATs files in the past but I cannot get them to read properly.
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Can you create an Argyll 'ti1' file for the synthetic data set that users can create patch sets for different papers? I've tried adapting CGATs files in the past but I cannot get them to read properly.
I haven't looked much at ti1 files but they appear quite specific to Argyll. Also, Argyll doesn't support i1iSis spectro so it's not an attractive approach.
Also, if I adopted only using Argyll tools there would have to be extensive revisions to the io in my code.
Argyll does have a nice conversion utility that processes I1Profiler CGATs files into ti3 files which work quite well for making Argyll profiles.
Since I1Profiler, unlicensed, can be used to create/print charts and save CGATs files it's a good alternative.
I've attached a file containing 6 files including the final icm profile. It's got a large B&W patch set, 0 to 255 step 1 repeated 3 times and scrambled. Much more than needed. A 52 patch set works just fine but this lets me average patches and evaluate print consistency compared to printing with regular color mode.
Here's a rough workflow:
Run the program to create patch sets. 52 and 256 CGATs sets are created with an option to make N duplicates to reduce the impact of printed patch variation.
Load the cgats file "256BW3x.txt" into I1Profiler by dragging and dropping it into the patch set block. Select the instrument and chart type then print it using B&W settings and whatever tint is desired. Save the settings for easy printing later.
Scan the target then save the result as a CGATs file making sure LAB is one of the selected fields. Spectral data does not need to be saved.
Next run the program with the name of the CGATs measurement file. This creates two new CGATs files that have RGB and LAB data. They have the original name with "RGBLAB" and "RGBLAB_adj" appended. These contain the RGB and measured Lab data as well as appended synthesized data to make profiling software happy. The "RGBLAB" CGATs file has the a* and b* fields zeroed while the "RGBLAB_adj" includes the measured Lab data.
Profiles can then me made by dragging and dropping these file into the Measurement tab of I1Profiler or, for Argyll profiles, running the CGATs files through the short batch file included. Both work.
The program then runs with the names of the two profiles and the white point and A2B1 table is copied from the "RGBLAB_adj" made profile into the "RGBLAB" made profile. The RGBLAB made profile can then be installed and softproofing performed. It will show proper paper white and any tint in the print.
The same profile can be used to print using the usual process with Epson printers or the workaround described earlier for Canon.
The profile included is from MP101 Matte on the Canon Pro1000. Ignore the name, it's from testing. Since the paper has a fairly large amount of OBAs and measurements were made with M1, having a L* min of 18, it makes for a pretty good demonstration of softproofing showing the blue shift of the OBAs.
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Doug,
Thanks for the extensive discussion. I don't have i1 Profiler and the work arounds for me are just too many steps. Perhaps Graeme will add something to Argyll that will give similar results to what you are getting and that might make things more interesting for me. I'll play around with the QTR derived profiles on my Canon Pro1000 to see if those make a difference with the B/W print path.
Alan
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Doug,
Thanks for the extensive discussion. I don't have i1 Profiler and the work arounds for me are just too many steps. Perhaps Graeme will add something to Argyll that will give similar results to what you are getting and that might make things more interesting for me. I'll play around with the QTR derived profiles on my Canon Pro1000 to see if those make a difference with the B/W print path.
Alan
Certainly would be good if Argyll had i1iSis support. Their support of spectros is exceptionally large otherwise.
As for QTR, it would be cool if they would add support for soft proofing that would show tint and paper white properly. It is doable and should result in very small but accurate profiles. Still, using them to print on Canon's requires the null trick. Works great but Canon should really not lock out custom profiles from the usual workflow which necessitates it.
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Wow.
I never realized how consistent B&W (even with tints) prints. I've finished the code. It does a great job of soft proofing with a much lower dE00 than color prints of neutral images. It also does a great job printing using standard "color" management techniques letting Photoshop manage and selecting the B&W profile. The statistics on same and nearby patch variations are markedly smaller.
Prints match the soft proof exactly with the strongest tint I can select.
My guess is that the consistency of ABW is because there is much less use of CYM inks except for a small amount required for the tints if used.
Just packaging it up to post on github later tonight.
It would be nice if Canon's printers would let you select custom B&W profiles like Epsons do to avoid the null transform trick needed to print on the Canon.
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I’ve been doing this for 8 years using True Black And White from Bowhaus on the 8300/8400s. They also supported the 24 inch models. It does everything you are discussing.
Grayscale workflow with easy color tinting if desired. Much simpler and intuitive than any of these qtr programs. You just print the patches and plug in the iI to yiur Mac ( Mac only). But for some screwed up reason they still haven’t released it for the new canons.
I don’t have a new canon but I email them every six months anyway. And they always tell me it’s about to be released. Canon has always allowed them to do whatever they need to do in the past. It is a stand alone program not an adjunct of the canon driver or photoshop plugin.
My prints are dead neutral on all the papers and you save warm or cool profiles for specific papers. It’s fast and painless. I remake the curves which they call profiles, after head changes but probably isn’t necessary.
I just don’t think enough people are demanding them to finish it up writing code for the new Canons - and they keep coming out with new ones, who knows. People want everything great like that to be free and it costs $200.00, where Studio Print is about two grand to do similar monochrome linearizations on all the printer platforms. You softproof the file right in the software window.
If interested everyone should email them. The interface is smart, clean, and non geeky simple. What canon should have written from the beginning.
http://bowhaus.com/trueblackandwhite/truebw.php4
John
Wow.
I never realized how consistent B&W (even with tints) prints. I've finished the code. It does a great job of soft proofing with a much lower dE00 than color prints of neutral images. It also does a great job printing using standard "color" management techniques letting Photoshop manage and selecting the B&W profile. The statistics on same and nearby patch variations are markedly smaller.
Prints match the soft proof exactly with the strongest tint I can select.
My guess is that the consistency of ABW is because there is much less use of CYM inks except for a small amount required for the tints if used.
Just packaging it up to post on github later tonight.
It would be nice if Canon's printers would let you select custom B&W profiles like Epsons do to avoid the null transform trick needed to print on the Canon.
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If interested everyone should email them. The interface is smart, clean, and non geeky simple. What canon should have written from the beginning.
http://bowhaus.com/trueblackandwhite/truebw.php4
John
Only works on MacOS and Canon Pro-1000 is not supported so this doesn't help me at all.
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See for answer to thread question:
https://forum.luminous-landscape.com/index.php?topic=137211.msg1204027#msg1204027
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Would like to see a neutral measurement of an ABW print. Thusfar i was not able to.
For my Printing i do my own profiling, and with a focus on neutral aka grey behaviour. So each profile is tested with amongst others a grey ramp , linear in L-ab color space with steps of 2% for L and a and b equal 0.
When printed ideally is should give straight lines from paper-white to black , normally i print relcol plus bpc
of course the bpc will give a deviation. As you can see in attached screencopy of such a test.
Here the a and b values follow the ‘straight line’ quite well.
So , in what area would ABW give an improvement if I print a black-white image?
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I have many dozen or prints (some printed by others like those who worked on the Epson Print Academy, many I've made) where the B&W prints appear totally neutral; under many kinds of lighting all output using Epson Advanced B&W mode, no profiles.
I can measure them but I don't see the point; they appear totally neutral. That's the actual color appearance.
Colorimetry and the dE testing and the creation of profiles is about (based on) color perception. It is not about color appearance. There's a significant difference. The reason why viewing a print is more valid than measuring it is because measurement is about comparing solid colors. Color appearance is about evaluating images and color in context which measurement devices can't provide. Colorimetry was never designed as a color appearance model. It was never designed to even be used as an interchange space between device dependent color models. It's not designed for imagery at all. Colorimetry based on solid colors in very specific ambient and surround conditions.
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Would like to see a neutral measurement of an ABW print. Thusfar i was not able to.
For my Printing i do my own profiling, and with a focus on neutral aka grey behaviour. So each profile is tested with amongst others a grey ramp , linear in L-ab color space with steps of 2% for L and a and b equal 0.
When printed ideally is should give straight lines from paper-white to black , normally i print relcol plus bpc
of course the bpc will give a deviation. As you can see in attached screencopy of such a test.
Here the a and b values follow the ‘straight line’ quite well.
So , in what area would ABW give an improvement if I print a black-white image?
ABW uses much less of the color inks. Just enough to sort of correct for small a,b shifts each of the neutral inks have. The result is smoother transitions across L*, a* and b*. For instance if you print L* = 50.0, 50.5, 51, 51.5, 52.... the patches printed using color have larger variations in L*,a* and b* compared to ABW. On my Epson 9800 those variations are about half what they are with color printing. These tiny changes no profile can correct. They are intrinsic to the driver's inking algorithms.
Also, the 9800 driver's RGB response is much smoother in ABW which makes the profiles work very well, even smaller LUT profiles.
ABW profiles thus are more accurate than color profiles for these reasons. But do they matter? No, they don't. Unless you are doing something really weird.
An example of a semi-crazy thing is to print a nearly black image in color mode and ABW. Say by shifting the white point on an image from L*=100 to L*=40. Then, instead of illuminating it with 500 Lux, use 5,000 Lux. This will make the L*=40 area as bright as unprinted paper under 500 Lux. And you will then be able to just see areas of transition noise that become apparent in the color print while it's much smoother in the ABW print.
Obviously this isn't a normal condition so it would be the rare case where it would matter. One possibility is in an exhibit where one is creating an image that seems to shine a bright beam of light from a small area of a print. By using ultra bright illuminating lights and carefully exhibiting the print in a very black matte frame and surround one can create a rather unique effect. ABW would do much better for this than standard color mode B&W printing.
The other thing that ABW profiles bring is consistency between printers and the ability to soft proof with accurate rendition of any tint that is actually there. Especially useful for something like Sepia prints.