Little help for an operator kept in the dark

[Colornumber9]

I'm a press operator with a limited understanding of color management. I realize there are thousands of posts here as well as a wealth of information beyond that to explore, but I'd rather get schooled by people who deal with this daily and can provide tangible answers to a few simple questions.

As I said, color management is an area I barely understand. I do know, however, that the color management my company has in place is not working. We (the press crews) have all tried and tried to get answers from those involved with its implementation to no avail. They're wholly uninterested in our involvement with managing color. It seems they would rather keep us in the dark spinning our wheels chasing a proof that matches our press sheet on about 1 out of 100 jobs.

While I'm doubtful that this will change any time soon, I would like to gain a better understanding of how color management is supposed to work. I've worked in a number of shops that had it together, but we were too busy MATCHING PROOFS and actually being productive to wonder how the hell it all came together! I know this is a broad subject and the questions below probably make me look like a complete fool, but I have to start somewhere. Any pertinent information would be much appreciated.

1. How is a color management system implemented? What is its primary goal? How are standards identified and maintained?

2. What are the most important factors when it comes to managing color?

3. Where do profiles and workflows fit into color management systems?

4. Something I hear a lot is "That job didn't match because it wasn't color managed." or "It wasn't run through our color server." Is there any reason why a job wouldn't be color managed?

5. Which device should be calibrated to which other device? Should a press be calibrated to a proof, or vice versa?

Again, I'm just trying to get a basic understanding of this for now. I'd like to figure out why a company that's been in business for over a hundred years with great production personnel and great equipment is losing customers because it can't match a proof for crap.

Thanks.

 

[meddington]

We (the press crews) have all tried and tried to get answers from those involved with its implementation to no avail. They're wholly uninterested in our involvement with managing color. It seems they would rather keep us in the dark spinning our wheels chasing a proof that matches our press sheet on about 1 out of 100 jobs.

Sad but true. The "pressroom" is often the most difficult undertaking in ia color management implementation, and the one area likely to be avoided or neglected. unfortunately, this is also where the rubber meets the road. Has your press been "characterized" or otherwise undergone a calibration/optimization process...or at least have a process control system in place with target values (densiometric or colorimetric) for operators to aim toward? Ignoring the pressroom completely is a recipe for mediocrity, or worse.

1. How is a color management system implemented? What is its primary goal? How are standards identified and maintained?

Huge question with many different possibilities. Rather than try to tackle it in a couple sentences, I should probably refer you to a more complete source, like "Real World Color Management" by Bunting, Murphy and Fraser or "Understanding Color Management" by Abhay Sharma.

2. What are the most important factors when it comes to managing color?

quick answer: consistency. If a device cannnot be brought into a consistent, predictable state of output, color management will not help (or it may only help in 1 out of a 100 times).

3. Where do profiles and workflows fit into color management systems?

Again, another broad question with many possible answers. refer to answer to #1. Might mean more to also get a description of the system/workflow used at your company.

4. Something I hear a lot is "That job didn't match because it wasn't color managed." or "It wasn't run through our color server." Is there any reason why a job wouldn't be color managed?

Very difficult to NOT color manage in some manner, but there could be cases where clients request no conversion to their files. That's not an excuse for unpredictable output however. Files that undergo no "conversion" should still be proofed on a device that accurately predicts the final output so the client can see the results of the workflow.

5. Which device should be calibrated to which other device? Should a press be calibrated to a proof, or vice versa?

Back in the film days, proofs were generated from the same film that generated the plates and the press was adjusted to match the proof. That proof used laminate that attempted to accurately predict printing processes. Modern proofing systems are likely inkjet devices that were design for many different purposes, and will not by default represent any particular printing scenario. But with color management, the printer can often be adjusted to match the output conditions more accurately than traditional proofing (IMO). There are lots of opinions, but consider that an inkjet proof not attempting to match a standard output or press condition is not really a proof...just a pretty picture. So the proof must match the "press". This "press" can either be a an industry accepted characterization, such as Gracol1, Swop3 or Fogra39 (among others), or a custom profile based on a specific press condition (the one you operate for example, which may have deviations from standardized characterization data). So either matching standard data or custom data can be successful, but press output needs to be consistent.

A lot of times proofs are matched toward a printing standard, but the press is left to its own accord. Adjusting press output by ensuring proper press setup and process control, and adjusting primary inking and plate compensation curves toward standard output often goes a long way in aligning press and proofing. If your press consistently deviates from standard data sets, you might benefit from either a custom proof condition based on your press, or a workflow that converts color output toward your press conditions just prior to generating printing plates. Either way, press characterization/profiling is required.

hope that helps.

 

[Michael Lunney]

Basics of Color Management

Basics of Color Management

First off, you don't sound like a fool at all . . . just, as you said, in the dark. If anyone is being foolish it's your management for not welcoming your involvement and encouraging you input. That being said, let's see if I can help shed a little light on the topic.

Basically, color management is all about consistency and predicability. The idea is that if your pressroom prints constantly, you can predict the outcome well enough to proof to another device/media. Consistent press runs require disciplined press procedures which include running to standard densities, proper packing of plates, consistent laydown order, control of physical issues like slur, dot gain, and tack, etc. The goal would be to have all your presses printing as closely to each other as possible and to minimize the "on press" correction for any shortcomings in the job or on the press. That's the starting point.

After you have control of the presses, the next step is to settle on what you want to calibrate two. In this area, there are two basic methodologies: match to your specific press environment or match to a specific industry standard. Each has the pros and cons and both can be successful if handled properly. Considering that most ink formulations and printing equipment is built around certain industry assumptions, many choose to print to a standard like SWOP or Gracol. This entails getting your presses to print within the constraints of the chosen standard and then making your proofs based on that standard. The other method entails "fingerprinting" your presses and making your proofs match that fingerprint. In either case, the press room has to be dealt with first since the proof is designed to match it's output.

The actual color management can be done in a variety of ways and in one of many places in the workflow. It can be handled by ICC profiles or it can be handled by look up tables. It all depends on what software you have, how sophisticated your customers are, and where in the process you think color management best fits. The end result, however, should be just as consistent and predictable as the pressroom itself. If that is the case, then you will get consistent plates from prepress which actually help you meet your press goals rather than exacerbate the process.

The sad truth of the matter is that MANY print shops don't involve the press room in the situation at all. They either don't want to interrupt production to properly refine the press room procedures or they just don't see the value in "fixing what isn't broke." As a result, such shops have spotty success and often find themselves chasing their own tails. That may be what your experiencing at your shop. Unfortunately, for all those involved, this leads to great frustration and stress and a continuous "fire fighting" mindset which does little more than lower moral and profit. And if that is what you are experiencing, it is a tough row to hoe, but you may take some solace in the fact that you are not the only ones faced with this problem.

Well, I hope that gives you some idea of how color management should work and perhaps you can see where it is failing in your establishment. At the end of the day, the specific means of color management are far less important than the active desire to control the process and actually manage the color. Until your company makes a commitment to actually control their processes, it is really moot whether they use ICC profiles or not. Color management is the most fundamental form of process management in the printing industry. After all, your customers are buying press sheets and most don't care how you get from their file to the final sheet as long as it looks like they expected it to look.


Best of luck,
Michael

 

[Colornumber9]

Thank you both for such straightforward and accessible information. Meddington, I picked up one of the books you mentioned. I would still like to address a few of the points that were made in your responses.

The press has been calibrated numerous times, and we have densitometric (This means standard densities, right?) target values that are supposed to get us where we need to be. They rarely do. Almost every job is a compromise on color. I find myself running different densities on each job just to achieve a compromise. Our press' window of operation is very tight; we are running full UV inks, which IMHO takes much more attention and care to control and maintain control of than conventional inks. I keep a very close eye on dot gain, water, blanket packing, pressures, roller settings, etc. I think it's safe to say that, at least for my shift, the press is printing consistently.

We are a G7 certified company, and the official message I get from management is that we're printing to Gracol7 standards. However, we were certified on a conventional six plus coat press. We installed a 14-unit UV perfecting press a bit less than a year ago, which is what I'm running. It seems to me that this would present a problem for color management, since the printing conditions are so different. Is this just my ignorance of the subject, or would it make sense to examine that as a cause of our problems? I've gotten the feeling that being G7 certified is just another selling point, but they seem to espouse it's virtues and this leads me to expect some sort of follow through on actual implementation.

The point about making output devices is very interesting to me, because we have two inkjet proofers producing the color proofs we're supposed to match. We see jobs all the time where two proofs will have identical screen builds, whether it's front to back of the sheet, or form to form, and don't match each other. We find out they were output on different proofers. Is this the kind of thing where jobs need to be output on one proofer, or is it possible (and necessary) to make them output the same?

How is a proof curve different from a press curve? Do they rely on each other, or can they be adjusted independently?

I think our workflow is called Odystar. My question about profiles and workflows comes from the misinformation I receive from management. One guy says they're changing the curve, another says they're making adjustments to the workflow. What is the difference?

Thanks again for your help.

 

[DavidH]

Colornumber9,

I agree with the good advice already given by meddington and michael. Odystar, like most PDF workflow systems, is capable of applying ICC profiles and controlling dot gain/tone reproduction curves - the key thing is using them in an effective way and above all having consistency in your press.

You cannot match G7 just by having density targets to aim at (though this is part of it). Tone curves and gray balance are also needed. You can get a lot of information about G7 on its official website:
IDEAlliance
where you will find out about the targets that should be run regularly on press, and the popular IDEALink curve software which can be used to monitor the results and calculate corrections.

Also, I will mention that there is software "PressSync" available as an option to Odystar (disclaimer: I am employed by Esko Artwork, the makers of Odystar) which is designed to help with press standardization. You or your prepress dept can make contact with our sales/support channels if you want more information.

Regards,
David

 

[rich apollo]

Colornumber9,

1) If you are a G7 certified company then the calibration process sought to achieve specific colors in the primary and overprint colors - at whatever densities necessary. That's how you determined the target densities for that stock, running that ink, on that press, in your shop.

2) I would expect UV conditions to be different enough to require a calibration run dedicated to that production process. Have you ever measured/compared the primary and overprint colors from your UV process to the primary and overprint colors from your conventional process?

3) Yes, your Prepress department should/must work with your proofing devices to get them to output at least acceptably similar. Or, as you said, all proofs for a job must be output on the same proofer.

4) Typically the proofer and plating curves are completely separate. One has no direct influence on the other in the workflow.

5) The biggest thing you can do, is try to make sure the pressroom remains consistent. A proof is supposed to predict the output on press. Obviously if that output is variable it cannot be predicted.

 

[dimitri]

Being G7 certified doesn't mean that all the presses are achieving the same output. You got to calibrate each press. There are two ways to go about it. You can either measure LAB of solids and overprints and dot gain of both presses and adjust the plate curves of the latest press to match the one you did the calibration on, or, for added accuracy, do another G7 calibration on the new UV press.

The first approach is less accurate, but simpler. Some would argue against it, but when you practically deal with a number of presses and stocks, such simplification can have better efficiencies.

However, mind you that most likely the overprints of the UV inks are weaker than the overprints of the conventional press. So if the proofs are coming from a conventional G7 run, then you might not be able to hit the entire gamut. Also, there are different trapping properties between conventional and UV inks, regardless of what your ink manufacturer might say. The hues might be slightly different and for sure, you cannot expect to be running the same densities on a UV and a conventional press and expect to hit the same color. Keep in mind that you would have a bit higher dot gain in UV and that you have to lock in the UV light sequence; switching the lights on and off could result in significant dot gain differences.

If a UV G7 run has been done already, then the question is how succesfuly was it done, and then, do they have two proofing workflows, one from each calibration run? I mean, a press can be a messy thing by itself, you cannot allow variation in the proofing stage! And then, do you switch jobs from press to press? And on what proof are you running at such a case? In order to control that process, they need to be gathering press data constantly, evaluating them, and making adjustments if needed. Also, what units did you run the G7 calibration run on? It might well be that each unit prints slightly differently.

Another question: are your prepress guys reading this forum

Ask them what is your target dot gain, just to poke them a little bit. Or measure the density, LAB, 50/40/40 grey balance, and dot gain of the proofs (I hope they put some sort of color bar on that as well) and tell them the difference yourself. Do the same for a press sheet and compare. This is their job, but you might want to stir some waters by doing this.

 

[pthielen]

Matching color

Matching color

This is not a hard concept to grasp.

I am a former instructor of printing and a pressman of over 30 yrs. Here is how can be done.
By starting backwards, with the press. Dot gain and inks can alter color, so start by fingerprinting the press, then go to proofing. It will also save $$ since presstime is more expensive than proofing time.

Also, your press may be slurring between the units, so be careful. This can dramatically change the color consistency of the press.

Do not keep chasing the color problem from the press by changing inks, fountain solution and paper.

Calibrate the densitometers and spectrophotometers to the inks, not the proofs. I am sure there are many salesman who would love for you to try there products, but make sure that it will benefit the pressman first.

 

[comholt]

Dear Number 9:

You have a challenging but solvable set of technical problems. 1) Getting multiple presses to match each other and presumably G7, 2) Getting multiple proofers to match each other, 3) Getting proofers to match press, and then keeping them consistent so press matches proofer. At that point, you can run to densities and the press will match the proofs.

The more serious problem is getting management to acknowledge that there's a problem and then get together to develop and implement a strategy to solve the problem. Do you consider that feasible? If so, there are a variety of tools and methodologies available to help solve the problem. Please let me know if you'd like to discuss further.

 

[OonaghG]

We have recently started working to ISO Colour standards and we have one proofing device and press calibrated to producing colour at this standard. We have, though, experienced some teething troubles. On a particular job all the settings were correct and the printed should have had no difficulty matching press output to ISO proofs but it was way off. By chance we had a press engineer in that day and he took a look and it turned out that there was too much calcium (I think! A bit vague but iit's not my department!) running around the system basically from sloppy press cleaning. A proper wash up later and the job was spot on.
We have discovered that there are many variables in colour management & you need all departments working together and all doing their jobs well.