Interesting study from Ryerson University on expanded color gamut printing.

[Deleted member 16349]

An article on WTT reports on a study done by Ryerson University. The link to the article

http://whattheythink.com/articles/9...tudy-evaluates-expanded-color-gamut-printing/

In the article, there is a link to the study. I read through most of it and it was actually very well done and interesting, which is a refreshing change.

It is about the accuracy of printing spot colours on two digitial printing devices.

This is what I found of interest and some thoughts.

They chose to use digital printers because they are more consistent. Good point. If offset could be made more consistent, it would show similar positive results, which is a point I have been making for years.

The testing was done without regards to standards or G7. Straight from characterization of the printers and the target Lab values of Pantone colours to the printer outputs.

Lots of other interesting related issues that I won't bother to discuss.

If you are curious, read the study. They might have used a software that you are using.

 

[Correct Color]

The testing was done without regards to standards or G7.

Gee...

Go figure.



Mike

 

[[email protected]]

I have not read the study itself yet - but will. Based on the WTT article though, it seems like it is a comparison of software technologies and their abilities to convert spot colors into CMYKOG. Then the resulting conversions are evaluated by being printed on a P9000 which is an 11/c printer - hmmmm - and also an Indigo 7900 which presumably has 7 inks installed and those inks are CMYKOGV, and the OGV inks are formulated to the Pantone XG targets.

The article appears to be connecting the results to real world production but does not delve into what those real world production technologies are that this might apply to. Is this for printers who are using Epson P9000's for production? or the 13x19 Indigo?

"In an ingenious experiment, the whole PANTONE+ Solid Coated spot color library, consisting of 1,846 spot colors, was printed on the Epson P9000 and HP Indigo 7900, using CMYKOGV colorants. It is shown that the solutions are able to reproduce 89–94% of the spot colors on the Epson P9000 inkjet printer and 77–87% of the library on the Indigo 7900, both to < 2 CIEDE2000 (a typical tolerance in label and packaging work). The implications of the study are profound: as the systems were able to reproduce most of the spot color library, it is possible today to dispense with the traditional approach to spot colors and adopt an expanded gamut solution instead."

I think the last line goes a bit far or is at least too leading in connecting the study with the apparent ease of dispensing with spot colors. For sure, CMYKOGV puts more Pantone colors within reach and I believe that motivated, capable printers will make this work and do it well - but it will take work! In an offset environment it will require controlling two or more inks consistently over a run to be successful as opposed to a single, formulated ink. It's easy to imagine how attractive this is to print managers. I would hope they support their production lines in implementation and production.
-dan

 

[Deleted member 16349]

In an offset environment it will require controlling two or more inks consistently over a run to be successful as opposed to a single, formulated ink. It's easy to imagine how attractive this is to print managers. I would hope they support their production lines in implementation and production.
-dan

This is one of the points I think the study has gotten backwards. They imply that using extended gamut printing will make printing (assuming they mean offset) more stable. I would say that is backwards which your comment implies. Offset needs to be a more stable and predictable process for extended gamut printing to work well.

The problem with offset is not just consistency of solid density of the control patch. It is also the variation of how the image is printed around the plate cylinder in the press direction.

These kind of issues are of no interest to Ryerson or any of the other graphic arts institutions. But Reality sucks.

 

[[email protected]]

I've downloaded and started the study report. It looks like a very good and illuminating experiment with regard to the general ability of systems to convert Pantone L a b based colors into CMYKOGV and further, how well they perform as tested on the printers used. I mention that the P9000 is an 11/c machine in the context of it's available palette from which to draw when outputting OGV (and CMYK for that matter) but the introduction of the report suggests that the Epson was intentionally limited, I presume again, to create parity. Below are a couple of quotes of note from the introduction. Some benefits are more easily attained than others. I get "expanded color gamut". I get "ability to reproduce a large number of spot colors". "better accuracy on press" has got to be in comparison to CMYK only printing systems - and still is dependent on very stable systems. "ability to gang jobs" has the same dependencies of stability and becomes influenced by image placement on the (offset) sheet. It probably requires even more care in layout of colors than CMYK only due to higher expectations of the process.
I would love to hear results from printers of various technologies, especially offset but suspect that with the relative newness of CMYKOGV to the mainstream that those who are doing it profitably may be reluctant to share secrets of success. To that end is the second quote and I look forward to the progression towards future studies.
Thank you Dr. Sharma.

"The benefits of expanded gamut printing may

include an expanded color gamut, ability to

reproduce a large number of spot colors, better

accuracy on press, ability to gang jobs, less ink

changes and washups, environmentally friendly

solutions, etc."

and

"In future studies the intention is

to evaluate spot color accuracy on conventional

printing processes."

-dan​​​​​​​

 

[Deleted member 16349]

I've downloaded and started the study report. It looks like a very good and illuminating experiment with regard to the general ability of systems to convert Pantone L a b based colors into CMYKOGV and further, how well they perform as tested on the printers used. I mention that the P9000 is an 11/c machine in the context of it's available palette from which to draw when outputting OGV (and CMYK for that matter) but the introduction of the report suggests that the Epson was intentionally limited, I presume again, to create parity. Below are a couple of quotes of note from the introduction. Some benefits are more easily attained than others. I get "expanded color gamut". I get "ability to reproduce a large number of spot colors". "better accuracy on press" has got to be in comparison to CMYK only printing systems - and still is dependent on very stable systems. "ability to gang jobs" has the same dependencies of stability and becomes influenced by image placement on the (offset) sheet. It probably requires even more care in layout of colors than CMYK only due to higher expectations of the process.
I would love to hear results from printers of various technologies, especially offset but suspect that with the relative newness of CMYKOGV to the mainstream that those who are doing it profitably may be reluctant to share secrets of success. To that end is the second quote and I look forward to the progression towards future studies.
Thank you Dr. Sharma.

"The benefits of expanded gamut printing may

include an expanded color gamut, ability to

reproduce a large number of spot colors, better

accuracy on press, ability to gang jobs, less ink

changes and washups, environmentally friendly

solutions, etc."

and

"In future studies the intention is

to evaluate spot color accuracy on conventional

printing processes."

-dan

I am sure Gordon knows the long history of efforts to run expanded gamut prinitng on offset and hopefully he will comment.

​​​​​​​

 

[gordo]

I am sure Gordon knows the long history of efforts to run expanded gamut prinitng on offset and hopefully he will comment.

You rang?

Note, for those that don't know me, that I was on the development team for the Creo/Kodak Spotless Solution so I only have practical printshop experience with expanded gamut printing garnered when I worked at Cre/Kodak.
Kodak seems to ignore their Spotless offering - e.g. they didn't have it in their booth at LabelExpo in Brussels last year which was surprising because EG printing was on display at several vendor booths and label/packaging is a perfect fit. Oh well.

I honestly don't see the value in this particular report. I don't believe the inkjet printer, nor the HP printer, they used would be suitable as a print production output devices for labels and packaging.

But I digress.

The report also does not deal with the practical business/prepress side of implementing an EG system. That, is a key barrier to adoption of this old technology.

Did the report include the Lab values of the ink hues? I didn't see that.
Also Abhay bemoans that Pantone 2433 was rendered in CMYK as opposed to using the EG Orange ink. Since it's in gamut for CMYK why should it use an EG color+process? BTW Pantone 2433 isn't in my Photoshop CC's Pantone Library. To his credit he did discuss the mess Pantone has made regarding color and its documentation.
Also, Abhay recently did a webinar on this topic. One attendee's question was: "What about screen angles?" (e.g. the HP in the test uses screen angles). Abhay couldn't answer that basic question.

I think folks should wait to see what his next study reveals when Abhay tests EG on flexo and offset.

 

[Deleted member 16349]

I honestly don't see the value in this particular report. I don't believe the inkjet printer, nor the HP printer, they used would be suitable as a print production output devices for labels and packaging.

But I digress.

The report also does not deal with the practical business/prepress side of implementing an EG system. That, is a key barrier to adoption of this old technology.



I think folks should wait to see what his next study reveals when Abhay tests EG on flexo and offset.

I do see value in the report but probably not in the way you might think or in the way the authors might have thought. As I see it, they used those digital printers for the very fact that they were consistent and predictable. I don't see that they were thinking of those printers to be production printers but more or less to be test bed printing devices. Of course consistency and predictability would be a requirement if one was testing the method of reproducing specific colours and their gamuts. No point in doing that with inconsistent devices.


I think this does deal with the practical implementation of an EG system or any other system. It is generic and can be applied to any consistent and predictable printing process. The authors are probably not aware of what they are saying. IMO what is said is that one can go from a colour target to the colour output, with a characteristic profile that maps the printing device, without any need for curves or G7.


The study just deals with spot colours but it can be applied to images too as long as Lab values are NOT used. It is basically the same method but there is a need to make the colour at the pixel level equate with the colour at the screen level. It should be easy to do if one uses the appropriate colour values for the needed calculations.


EG is being used now probably more often with flexo. There are groups doing it. Flexo is more consistent than offset and therefore is probably a better fit. When the offset process is fixed to eliminate or at least greatly reduce the variation, I expect that EG will be predictable in the way this study showed.


Do I think Ryerson will know what to do with offset in relation to this issue? No, I don't. They don't have any deep understanding of the process.


But on this study, I think they did a pretty good job even if they don't fully understand the implication of what they have done.

 

[gordo]

I do see value in the report but probably not in the way you might think or in the way the authors might have thought. As I see it, they used those digital printers for the very fact that they were consistent and predictable. I don't see that they were thinking of those printers to be production printers but more or less to be test bed printing devices. Of course consistency and predictability would be a requirement if one was testing the method of reproducing specific colours and their gamuts. No point in doing that with inconsistent devices.

If they're just testing gamuts and the ability to hit specific PMS colors or determine the recipes that the software came up with then there is no need to print their tests. They could have done the evaluations in software.

EG is being used now probably more often with flexo. There are groups doing it. Flexo is more consistent than offset and therefore is probably a better fit. When the offset process is fixed to eliminate or at least greatly reduce the variation, I expect that EG will be predictable in the way this study showed.

I haven't seen any data on the number of EG installs in either flexo or offset. Judging by what I've learned talking to printers at trade shows like LabelExpo in Europe and N A I doubt that there are more flexo printers doing EG than offset.

Since 2001, I know that hundreds of thousands of labels and packages are printed weekly using offset. When coupled with heavy GCR and FM screening it appears to be stable enough on offset presses to meet customer requirements.

Do I think Ryerson will know what to do with offset in relation to this issue? No, I don't. They don't have any deep understanding of the process.

Nor the information that printshops need in order to determine how to implement EG printing.

But on this study, I think they did a pretty good job even if they don't fully understand the implication of what they have done.

Every once in a while the patients of witch doctors have a successful outcome. It doesn't mean the witch doctor did a good job.

 

[Deleted member 16349]

Every once in a while the patients of witch doctors have a successful outcome. It doesn't mean the witch doctor did a good job.

Ouch! I thought I was tough on the "experts". You beat me on this one. No mercy Gordon.

 

[Schnitzel]

I don't believe the inkjet printer, nor the HP printer, they used would be suitable as a print production output devices for labels and packaging.

HP Indigo has several labels and flexible-packaging machines. The equivalent of the 7900 in the article would be the 6900. I personally operated the 6000 model for several years. It's a good machine, but it suffers from color drift in long runs as expected from a laser printer, so the consistency and predictability of digital presses can be argued. HP Indigo has inline color correction solutions for the web presses but they require printing a color wedge that eats away at the web's free space, which is limited to begin with.

Another problem is that HP Indigo has only 7 color stations. Web printing requires CMYK + white, and that leaves only 2 free stations. So no OGV for you! On top of that, I can tell from experience that customers weren't so eager to pay for the extra separations just to print their brand color. They almost always went for a less accurate CMYK match. So the willingness of customers to pay for extended-gamut must be weighed in this discussion as well.

 

[Correct Color]

I mention that the P9000 is an 11/c machine in the context of it's available palette from which to draw when outputting OGV (and CMYK for that matter) but the introduction of the report suggests that the Epson was intentionally limited, I presume again, to create parity.

Note that while the Epson has more colors, its primaries are CMYKOGV. The other colors are all lights and do not increase gamut. Any gamut increases from the Epson to the Indigo would basically be profile-related in some form or fashion.

I think this does deal with the practical implementation of an EG system or any other system. It is generic and can be applied to any consistent and predictable printing process. The authors are probably not aware of what they are saying. IMO what is said is that one can go from a colour target to the colour output, with a characteristic profile that maps the printing device, without any need for curves or G7.

Exactly.

Of course, that's true of CMYK just as much as it's true of CMYKOGV.

Personally, my take after years in large-format printing where gamut-expanding inksets and non-standard primaries are pretty common, is that:

I agree that it's one thing to keep a large-format printer stable, and another to attempt the same thing with an offset press. Is it really more cost-effective to try to mange a seven-color offset press than to just ink up a unit or two and run spot colors?

A few years back, CMYKOGV was wildly popular. Several manufacturers came out with CMYKOGV inksets. Or CMYKOG, of which of course the old, dead, unlamented Hexachrome was a variant. But what happened was that on lots of printers, the green ink would go bad in the cartridges because it seldom fired, and lots of manufacturers have since dropped the green.

If there's one color to add, it's orange. Orange in the inkset is invaluable because you can't have a magenta that will allow you to get good oranges and good purples. A hot magenta will get you close to oranges but not there, at the expense of purples; while a cold magenta will give you good purples, but you can forget about satisfying anyone who wants PMS 021. However, what's true is that there are a lot more clients about there wanting a host of particular oranges than there are wanting particular purples. So it winds up that if you have a cold magenta and orange, and really strong profiles, you can get pretty damn close to CMYKOGV.



Mike Adams
Correct Color

 

[gordo]

Is it really more cost-effective to try to mange a seven-color offset press than to just ink up a unit or two and run spot colors?

Yes!

The offset installations that I have had experience with may have a 7 color setup but they typically run a six color setup. I.e. they don't have 7 colors on the press all the time.

They pre-plan jobs to run C,M,Y,K,B/V,O/R for a shift then replace the V with G for the balance. I.e. one washup and ink change over.

They'll often run the brand color as a line color rather than a screen tint blend (depends on the brand owner). If the brand color is out of CMYK gamut they may use it as one of the extended process colors - i.e. instead of the V/B, O/R, or G.

They typically run gang label/packaging jobs this way. There are many business opportunities that arise by working this way.

It is an extremely cost effective production process and VERY profitable. It is one of the main reasons that, when I worked at creo/Kodak, none of our customers would provide a testimonial that we could use in marketing our EG solution despite those printers running the EG process 3 shifts a day, for years, on hundreds of thousands of label/packages globally.

This is an actual live production sample:

 

[Deleted member 16349]

I agree that it's one thing to keep a large-format printer stable, and another to attempt the same thing with an offset press. Is it really more cost-effective to try to mange a seven-color offset press than to just ink up a unit or two and run spot colors?


Correct Color

What I have been trying to say for over twenty years is that the offset process can be made consistent and predictable. The interesting thing is that it can be made to be more consistent than digital. It really depends on how the press is designed. People will not believe this but eventually it can be shown. In principle, it is a lot easier to design a consistent ink feed for offset, which would not require closed loop control, than it is to make the ink/toner delivery of digital printing processes consistent. Just now, the digital systems seem to require closed loop to compensate for drift.

My view has also been that standards have held back the process and possibly harmed the business of printing. I would think that printing product for a customer, that can have a wider range of colours, would help business. It would also benefit from a more generic approach to colour management that is not restricted by standards.

There is a potential for innovation in inking systems for offset that might counter the existing concerns. Closed systems that positively feed ink into the roller trains, and which can be easily lifted out and replaced with another ink feed unit that has a different EG colour could make things work quite easily. I have thought about this type of option for years. So many things are possible if there would be the motivation to do it.

 

[Correct Color]

In principle, it is a lot easier to design a consistent ink feed for offset, which would not require closed loop control, than it is to make the ink/toner delivery of digital printing processes consistent.

Just to note that when I say large-format, I mean inkjet. Toner is another story.

My view has also been that standards have held back the process and possibly harmed the business of printing. I would think that printing product for a customer, that can have a wider range of colours, would help business. It would also benefit from a more generic approach to colour management that is not restricted by standards.

I agree completely.



Mike

 

[[email protected]]

Here's a newly released (yesterday) conversation with Dr. Kiran Deshpande of Siegwerk regarding ECG. Part one of what will be a two part discussion. -dan

https://www.buzzsprout.com/episodes...olor-gamut-ecg-revolution-is-going-mainstream

 

[gordo]

Just for the record, it’s interesting that the factors that Dr Kiran discusses in the audio as being requirements for successful EG implementation were already part of the creo Spotless solution 10 years ago.

 

[[email protected]]

Noted! and thanks for your participation here and confirming my suspicion that successful implementers would be tight-lipped. Would it be too tongue-in-cheek to say let's see what the future holds?
-dan

 

[gordo]

Noted! and thanks for your participation here and confirming my suspicion that successful implementers would be tight-lipped. Would it be too tongue-in-cheek to say let's see what the future holds?
-dan

It’s easier to predict the past.
I think EG will remain in limited use for the near future. The barrier to greater adoption IMHO is that it requires printers to think counter to their culture. It also requires that they adopt a marketing mindset which is typically not their strong point.

 

[JohnTheMathGuy]

I was one of the advisors on the study. I hope I can clear up some of the questions / misperceptions.

First, I appreciate the interest in the topic!

We had much discussion about the tests before we began. One of the decisions was to keep the focus narrow so we could get results out quickly. We decided to start with testing whether the various pieces of software could create CMYKOGV builds that worked.

Gordo said: "If they're just testing gamuts and the ability to hit specific PMS colors or determine the recipes that the software came up with then there is no need to print their tests. They could have done the evaluations in software."

Yeah, that would have made our test easier! But how would we test the builds? We could use the software itself to test whether it agreed with itself, but that presumes that the software will accurately predict the color of the build that it came up with.

Erik commented: "They chose to use digital printers because they are more consistent."

Exactly. Remember, our intent was not to test the digital printers, but to test the software. It was felt that digital printing was the most consistent, so this was our starting point. Another big benefit for digital is that it can be done very quickly. Quick turn-around enabled us to work the kinks out of the test quickly.

Gordo said: "I think folks should wait to see what his next study reveals when Abhay tests EG on flexo and offset."

Planning for phase 2 is currently underway. We have not officially settled on flexo or offset, but are leaning toward flexo.

One consideration is that flexo packaging seems to be of greatest interest. Another consideration is that Clemson and the Sonoco facility have agreed to run the tests on their flexo press. This press has a Techkon inline spectro, which offers some advantages in terms of gauging stability.

Since I am (at this very minute) in the process of moving to the Clemson area (I will be teaching there next semester), I will be closely involved in the next round.

Dan said: "Then the resulting conversions are evaluated by being printed on a P9000 which is an 11/c printer - hmmmm - and also an Indigo 7900 which presumably has 7 inks installed and those inks are CMYKOGV, and the OGV inks are formulated to the Pantone XG targets."

We were testing extended gamut as it is currently being commonly used. All printing was done with seven inks: CMYKOGV.

Erik said: "The testing was done without regards to standards or G7. Straight from characterization of the printers and the target Lab values of Pantone colours to the printer outputs."

Erik later said: "The authors are probably not aware of what they are saying. IMO what is said is that one can go from a colour target to the colour output, with a characteristic profile that maps the printing device, without any need for curves or G7."

There were further comments which were perhaps a bit disparaging, so I will provide some defense.

The printers were set up by strictly following manufacturers recommendations. As soon after this as possible, the press was profiled. As soon as practical after that, the spot colors were printed. Thus, I can say that for the purposes of this test, process control of solids and tint ramps was irrelevant. It is assumed that the press can remain consistent over a period of several hours.

I recognize that these conditions are far from what one would expect in the field. Let me re-reiterate -- we were intentional in deciding to initially test the software in as pure of a condition as possible.

The question of stability is more grist for further tests. I will discuss this further with the group. I think that there are tests along this line currently being undertaken by some Clemson students. I will find out more when I get settled in.

Gordo said: "Did the report include the Lab values of the ink hues? I didn't see that."

The target values were the L*a*b* values from the Pantone library. I think Abhay mentioned that having everyone use the same library was an initial issue that needed to be sorted out!

I have the measurements of all the output sheets, but I am not at liberty to share these -- one of the conditions of the project. But if anyone has a suggestion of what to look at, I might be persuaded.

Erik said: "The study just deals with spot colours but it can be applied to images too as long as Lab values are NOT used. It is basically the same method but there is a need to make the colour at the pixel level equate with the colour at the screen level. It should be easy to do if one uses the appropriate colour values for the needed calculations."

From discussing this with the software folks at the various companies, I understand that spot colors and images are treated differently. I won't go into details here.

Gordo said: "I haven't seen any data on the number of EG installs in either flexo or offset. Judging by what I've learned talking to printers at trade shows like LabelExpo in Europe and N A I doubt that there are more flexo printers doing EG than offset."

I suggest attending an FTA conference. Perhaps your view may change?

Gordo said: "The report also does not deal with the practical business/prepress side of implementing an EG system. That, is a key barrier to adoption of this old technology."

Time to re-re-reiterate. I agree that practical concerns are vital to the adoption of any technology, but this is beyond the scope of the initial phase of the project.

Gordo said: "It [expanded gamut printing] is an extremely cost effective production process and VERY profitable."

Exactly. All the rest of the discussion of consistency takes a back seat to the big point. For a printer who does multiple changeovers a day of largely spot color work, the savings are huge.


John Seymour
John the Math Guy, LLC