Concentric screening

[Colornumber9]

Concentric screening is something I've heard management talking about for a while now. We've run two test forms and are apparently heading in that direction for our standard screening. I've read some literature on it but can't find much practical information about how it acts on press, what I can expect will need adjusting, etc. How does it compare to FM screening for color gamut, detail, press stability, etc.?

Any insight? This is a sheetfed, high-end commercial shop running full UV inks and perfecting 75% of the time.

Thanks.

 

[jlind]

I don't think there is much difference between concentric screening, stochastic screening, and 300 lpi AM screening. If your process control is good enough for one, it's good enough for the other.
John Lind
Cranberry Township, PA
724-776-4718

 

[gordo]

Concentric screening is something I've heard management talking about for a while now. We've run two test forms and are apparently heading in that direction for our standard screening. I've read some literature on it but can't find much practical information about how it acts on press, what I can expect will need adjusting, etc. How does it compare to FM screening for color gamut, detail, press stability, etc.?

Both press room and prepress will need to be concerned.
Concentric screening is really an AM screen ruling multiplier and will have similar behaviour to any very fine AM or FM screen and carry many of the same benefits.
Essentially, the screening math is hampered by geometric constraints (angle, resolution, lpi, dot shape + ring width). Visible structure is kept to a minimum by specifying very narrow rings, BUT this pushes the effective frequency so high that process stability and imaging are compromised. Even when screens are free from visible artifacts, they are often so fine that it is difficult to support their use on plate let alone find a way to implement them in the press room. The problem is that some concentric screen settings drive rulings way over what plate imaging can support - on the order of 1-2 pixel widths for the rings, which is understandably problematic. For example, a 200 lpi screen with 2 pixel ringwidths = 600 lpi which is finer than, for example, Kodak Staccato 10 (so in that sense John L is incorrect). You will need to work with your CTP and plate supplier to determine what frequency/ring size they are able to support.
Coarser ring widths are easier to implement but at that point it is probably more effective to use an AM screen of equivalent lpi. Since it is still an AM screen there is still the opportunity for screening and subject moiré - although the finer the screen the less likely that will be a problem.
From a print buyer point of view there will likely be no visible difference between a 2-300 lpi conventional AM screen and concentric screening - even under a loupe. You can confirm this yourself by looking at the Concentric screening brochure where the screens are compared at the same lpi.
If you want to go to higher lpi screening, then I would suggest you stay with conventional AM or go to FM.

best, gordon p

my print blog here: Quality In Print current topic: the creative production process

 

[Colornumber9]

Thanks gordo ... excellent blog by the way.

 

[rich apollo]

Something else to consider with Concentric screening. I believe that EskoArtwork handles the plate curves in kind of a "black box" fashion. So, to adjust your plate curves you have to contact EskoArtwork support and have them build the curve for you.

That would be a deal-breaker for me.

 

[Vee]

That would be a deal-breaker for me.

Ditto that.

 

[whoami]

Something else to consider with Concentric screening. I believe that EskoArtwork handles the plate curves in kind of a "black box" fashion. So, to adjust your plate curves you have to contact EskoArtwork support and have them build the curve for you.

That would be a deal-breaker for me.

We tested concentric here at our shop for a bit but we never really took it anywhere. But I distinctly remember making our own curves for it using the idealink software. Mark Samworth would be the guy to talk to at EskoArtwork. He's the godfather of concentric.

 

[sgirard]

I could be wrong. But I think the deal with the curves is that you build your own. However, if you do not want to do that for whatever reason you can send press sheets to Mark and he'll build them for you. We haven't implemented it here; that was my impression of the process though.

 

[whoami]

Yeah I think you are right sgirard. Now that I think about it we had to print out the Cyan channel first and then we sent the cyan sheet to Mark. He then told us what size rings and what line screen we should use. Then we printout out the CMYK and got our curves. He said he tell us right away what curves we should be using if we sent him a sheet but we decided to make the curves ourselves.

 

[PrepressDan]

Something else to consider with Concentric screening. I believe that EskoArtwork handles the plate curves in kind of a "black box" fashion. So, to adjust your plate curves you have to contact EskoArtwork support and have them build the curve for you.

That would be a deal-breaker for me.

This is false. With concentric comes a piece of software called PressSync. Presssync is the best thing I have seen for matching gracol spec. It has 400 built in curves for you to use. You still have the capibility to create your own curves if you want but after using presssync I don't know why anybody would want to. If anybody here has seen it I think they would agree that it is one of the best new curve management pieces of software in a long time.


Also, the 1 color test is not to set curves, it is to see if your current plate conditions are good enough to handle the screening. They first test with a 1 color tiff and if successful they can proceed to a harder test which is the 4 color test.

 

[DavidH]

Concentric screening is something I've heard management talking about for a while now. We've run two test forms and are apparently heading in that direction for our standard screening. I've read some literature on it but can't find much practical information about how it acts on press, what I can expect will need adjusting, etc. How does it compare to FM screening for color gamut, detail, press stability, etc.?

Colornumber9,

EskoArtwork run regular free webinars (given by Mark Samworth) that would answer your questions on Concentric. If you are interested, contact me offline and I will get you details.

The problem is that some concentric screen settings drive rulings way over what plate imaging can support - on the order of 1-2 pixel widths for the rings, which is understandably problematic.

Gordo,

Hats off to you for an excellent blog, but I don't think you are familiar with how Concentric is used in practice today. Yes, by choosing very high rulings and very thin rings its possible to create a pattern which almost no plates can image correctly - but its not necessary to go for such extreme parameters to get a good result with Concentric. We have many customers successful with Concentric on a wide variety of plate types and equipment.

Something else to consider with Concentric screening. I believe that EskoArtwork handles the plate curves in kind of a "black box" fashion. So, to adjust your plate curves you have to contact EskoArtwork support and have them build the curve for you.

That would be a deal-breaker for me.

Rich,

You are referring to the PressSync curve system that we include with Concentric. EskoArtwork does have a service that will make curves for you and many customers find this is a help to get them up and running rapidly. However:
(a) PressSync is not a black box and the curve selection remains under your full control
(b) we don't force users of our screening to work with PressSync. You can still make curves the old way if you prefer, but those who have tried PressSync typically do not want to go back to the previous methods.

Regards,
David Harris - Product Manager, EskoArtwork

 

[gordo]

Gordo,
Hats off to you for an excellent blog, but I don't think you are familiar with how Concentric is used in practice today. Yes, by choosing very high rulings and very thin rings its possible to create a pattern which almost no plates can image correctly - but its not necessary to go for such extreme parameters to get a good result with Concentric. We have many customers successful with Concentric on a wide variety of plate types and equipment.

Hi David,

Thank you for the comment re: my blog.
I know Concentric screening from a CtP/plate vendor's point of view. Because of the resolution requirements that this type of screening demands, Creo/Kodak only qualified certain plate/CtP/ring size combinations that they would support in the field. I don't believe anything in the screening has changed in the past year, so AFAIK, the restriction on supported combinations is still in place. I don't know if other plate/CtP vendors have similar restrictions (Agfa?, HD?, Screen? etc.)

If I made any incorrect statements in my original post in this thread, I sure would appreciate it if you could correct them.

PS, Please sign me up for any webinars you will be hosting on Concentric (or your other) screening. (I have a soft spot for any vendor that would call one of their screen sets: "Groovy Screens"

best, gordon p
my print blog here: Quality In Print current topic: the creative design/production process

 

[marktonk]

Good point, not all plates have the resolution to maintain very fine screens or fine FM. So you need to pick the right plate/plates for the application. Another factor is the laser/optics of the CtP device, is it capable of imaging the very fine spots/dots? Both need to be checked.

Regards,

Mark

 

[DavidH]

Good point, not all plates have the resolution to maintain very fine screens or fine FM. So you need to pick the right plate/plates for the application. Another factor is the laser/optics of the CtP device, is it capable of imaging the very fine spots/dots? Both need to be checked.

I agree with Mark and Gordo that not all plates/CTP devices are capable of working with Concentric. The same can be said about any other screen with a fine structure such as stochastic. Gordo explains why this is not as simple as just checking the nominal resolution of the CTP in his blog.

Like Gordo, I would prefer to see more clarity in CTP specs so that everyone can judge what applications each plate and equipment is best suited for. Ideally this should be given using a vendor-neutral metric that is not linked to a specific screening product, such as effective resolution (a number) or ability to resolve standard test patterns - eg checkerboards.

I know Concentric screening from a CtP/plate vendor's point of view. Because of the resolution requirements that this type of screening demands, Creo/Kodak only qualified certain plate/CtP/ring size combinations that they would support in the field. I don't believe anything in the screening has changed in the past year, so AFAIK, the restriction on supported combinations is still in place. I don't know if other plate/CtP vendors have similar restrictions (Agfa?, HD?, Screen? etc.)

Hi Gordo,
The fundamentals of Concentric have not changed but it does admit a range of parameter settings including rulings and ring widths. When Concentric was launched a couple of years ago, we did focus mainly on very high quality applications using high rulings and fine rings. Although these are still good cases for Concentric (if the CTP and plate can take it), other applications have been proven over time using less extreme settings - for example heatset web and newspaper printing.

Concentric is no more demanding on plate than other types of fine screening - you need to match the parameter settings to what the print application needs.

PS, Please sign me up for any webinars you will be hosting on Concentric (or your other) screening. (I have a soft spot for any vendor that would call one of their screen sets: "Groovy Screens"

I'll pass that request on to our USA sales and support team who run these webinars.

Regards,
David

 

[rich apollo]

You are referring to the PressSync curve system that we include with Concentric. EskoArtwork does have a service that will make curves for you and many customers find this is a help to get them up and running rapidly. However:
(a) PressSync is not a black box and the curve selection remains under your full control
(b) we don't force users of our screening to work with PressSync. You can still make curves the old way if you prefer, but those who have tried PressSync typically do not want to go back to the previous methods.

Our sister company just had a consultant, a fellow that I know pretty well, in to perform G7 calibration on their presses using concentric screening. He described the process as a "black box" operation in which they had to have tech support build and install the desired curves. Could the issue have been that he chose not to use PressSync, but instead was working with IDEALink Curve and SpotOn? Or could it be an issue of Odystar vs Nexus?

 

[DavidH]

Our sister company just had a consultant, a fellow that I know pretty well, in to perform G7 calibration on their presses using concentric screening. He described the process as a "black box" operation in which they had to have tech support build and install the desired curves. Could the issue have been that he chose not to use PressSync, but instead was working with IDEALink Curve and SpotOn? Or could it be an issue of Odystar vs Nexus?

Rich,
It could be a number of issues, not sure from the information I have. How about you and/or your consultant attend one of our webinars on PressSync to ensure you both have the latest information? PM me if you would like more details.

Regards,
David

 

[PrepressDan]

guys, if any of you are interested. This is the person to email about getting a invitation to the concentric and presssync webinars

[email protected]