Adobe Photoshop Training with Dan Margulis

One of our clients is considering a switch from printing offset to printing gravure. We have always used swop profiles for our cmyk space. Should we continue this practice or is it necessary to change (profile etc.)? Any other pitfalls we should be looking for?

all experiences welcome

thanks

Ken Willow

Image Studio Ltd.

Evanston, IL 60202

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Ken,

You might find help at this site (Gravure Assoc. of America):

http://www.gaa.org

Lee

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Separating for gravure is somewhat of an art form. In the lighter half of the image gravure behaves more or less as offset does, but special handling of the shadows is needed. All the inks, especially black, are in effect more transparent than offset inks, so the shadow will look too light if treated as offset. In gravure, the technical reasons for an ink limit do not exist, so a shadow of 95c85m85y85k is acceptable--but it doesn't always hold detail.

The additional options in the shadows mean that no one method of separation can even come close to handling all gravure images optimally. A reasonable start would be to set Total Ink Limit to 370%, Separation Type UCR or Light GCR, and Black Ink Limit 50-70%, understanding that the black channel will have to be adjusted once the separation is made because it will be too light.

In short, it takes longer to fix up a gravure image than it does one destined for offset. OTOH, the fact that it's being printed gravure indicates that there will be at least five zeroes in the number of copies printed, and if you're printing that many, you may as well print them properly.

Dan Margulis

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Hi Dan,

Speaking as an old gravure color separator and some one who works with gravure regularly, what you are suggesting might work, but... this could be a costly mistake to hack a Photoshop printer profile to create color separations for gravure.

If you are going to create high quality separation for a long run printing process you want to use a better color separation method than guessing at creating a Photoshop printer profile.

You want to first talk to the prepress person at the gravure plant and get the basic spec for creating a good separation.

What you will most likely find out the gravure printer will say something like:

" We use a pre-press proofing system such as a digital matchprint or Creo spectrum. If you use one of those systems, then send us some test files so we all can be sure your files are creating the right look on each of our proofing systems. Once that is established (and that might take a while) , then send us the file and proof and we will match it. "

In this scenario, what usually happens is that the business that is going to provide the color files and pages to the gravure printer will create a custom ICC profile and then create his or her own optimized color separation for their internal pre-press process.

Of course the gravure printer might offer you an icc profile for creating separations.

Using colorimetric measuring tools, a little color science, along with color savvy is one of the most effective ways to create custom color separations for gravure or offset printing these days.

As for a gravure printer not being able to hold shadow detail due to the offset color separation method and the ink limit. I find what you are say is hard to believe. Here is why.

You just need to know more about things like: The paper type, if the separation had the details to begin with, the gravure presses ink set, if the front end of gravure system is calibrated correctly and how much GCR is being used when the cylinders are being cut and on and on.

I see gravure working with separations that offer 300% to over 380% til. The point is, you don1t know why the prints come out in gravure with a loss of details until you know all of the particulars.

Jim Rich

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Jim Rich writes,

I want that, yes, but it is not always possible to get it.

The scenario you propose--having the printer supply a separation profile--can work very well, provided that ALL SIX of the following factors apply.

1) That you even know who the printer is going to be, as opposed to just knowing that "this job is being prepared for gravure."

2) That your client will permit you to talk to the printer.

3) That the printer is willing to talk to *you.*

4) That the person who is willing to talk to you has some idea what he's talking about.

5) That the printer has no objection on moral or other grounds to giving you his profile.

6) That the printer's profile is actually any better than a guess.

In short, it's just like dealing with an offset printer. Fortunately, a gravure printer is considerably more likely to be knowledgeable about these matters than an offset printer is. If it's an offset printer, the chances of all six of the above being true is probably <5%. If it's a gravure printer, the chances are probably more like 25%, IMHO.

Which leaves open the question of what to do in the other 75% of cases. It is hard to come up with any other option than to define the separation parameters in Photoshop. And even if the printer supplies one good profile, it won't be enough to take advantage of all the possibilities that the higher gravure ink limit offers.

In any event, as you noted, there is going to be a proofing stage. At that point, we will know whether the printer's profile is better than a guess, because with that much money on the line, anybody who doesn't proof with at least two different sep methods deserves what he gets.

If I had said it, it would have been hard to believe. What I actually said was that if a sep prepared for SWOP were instead printed gravure, the shadows would be *too light*, not lacking in detail. I added, "In gravure, the technical reasons for an ink limit do not exist, so a shadow of 95c85m85y85k is acceptable--but it doesn't always hold detail."

I can state categorically that not every gravure printer is capable of holding a 95c85m85y85k shadow with detail.

Dan Margulis

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Dan,

You list six important events that must take place for good communication and a good printed job. You then suggest that this takes place less than 5% of the time.

Why is this an acceptable standard of operation in this industry when it is not in any other modern manufacturing process? Imagine that the next time you fly on an airline that the plane was manufactured by subcontractors that communicated and followed standards the way the printing industry does!!!

Why has the printing industry not been able to adopt process control, international standards for inks, papers, color mesurements?

These standards exist. But you are saying that less than 5% are willing to follow them.

Why?

Ray Maxwell

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Ray Maxwell writes,

No, I listed six events that must take place for a specific scenario suggested by Jim Rich to be successful (namely, that the printer assists in the production of separations), and I suggested that all six of them take place simultaneously less than 5% of the time with respect to *offset*, not gravure, printing. I in no way stated or implied that good communication or good printing was impossible without these six events, only that Jim's specific scenario doesn't work without them.

The better printers have always had good process control, because not having it is very expensive in terms of waste. Those who have been held accountable for printing to agreed-upon specifications have done it well (but they may charge more than their competition).

Declaring that something is a "standard" for printing does not make it one. AFAIK, the only "standard" that is universally agreed upon is that, given a CMYK file that will not be converted or altered, a printer should be able to produce and to stand behind a proof that is a close representation of what will actually be achieved on press. It is not "standard" that a printer conform to SWOP or any other specification unless he has advertised that he does; it is not "standard" that a printer know how to separate an RGB file at all, let alone be able to tell a client how to do it.

I have always recommended that printers should have more knowledge of prepress realities just as I recommend that photographers learn more about printing. I also advocate sharing the printer's separation methods to those clients who indicate that they know how to use them and that they understand that a good separation method does not correct problems with the intitial RGB file. I do not advocate that printers be required to be a source of unlimited free technical support for matters Photoshop.

In any event, I don't see how "standards" deal with item #1 on my list. Particularly with respect to offset printing, I would guess that in the majority of cases the person preparing the CMYK file DOES NOT KNOW who the printer will be (or, if the printer *is* known, which press will be used). Under those circumstances it is extremely difficult for there to be the sort of meaningful interaction between them that both Jim and I would like to see.

I grant that when a job is going to be printed gravure, there's a much greater chance that we will know who the specific printer is going to be, and therefore Jim's scenario is more likely to be applicable. If it is, I certainly endorse it. But if it isn't--if the printer isn't known, or if the printer can't or won't share information, or if the printer's information is no better than a guess--Photoshop does not offer a built-in method of separating to gravure standards. In that case, there are two options:

1) Do the things I suggested, or similar things;

2) Abandon the job and gripe about "standards".

Dan Margulis