By Howie Fenton
Color management is a technology that some people applaud and others criticize. The obvious question is what separates the successes from the failures.
In the first article in this series we talked about the good and bad parts of color management, the dropping prices for the tools and improvements in technology, and introduced the first “Ugly” which is process control. In this the second article of a two-part series, we will discuss more about the role of process control and more importantly discuss the problems with using profiles for presses and introduce and alternative strategy which is showing promise in early tests.
However, ask anyone about the goals of color management: making color appear more consistent and reliable from your scanner, monitor, proofer and press run – and everyone agrees that those are goals are worth pursuing.
Publishers Press
Pioneering new technology is nothing new for Publishers Press who created the first magazine – Sports Car International – published using CTP in May 1994. Publishers began working on color management in 1999 and discovered the issues in process control.
Publishers has four Fuji Celesis scanners at the Shepardsville plant and one at the Lebanon Junction plant. Every week all the scanners were tested for calibration and adjusted if required. However, when the scanners were tested for acceptable drift and consistency between scanners, a problem was discovered.
According to Dan Millsap, the Manager of Electronic Pre-press Digitizing & Imaging in the Shepardsville plant, “We had no idea that four scanners were not all working consistently and the same. We calibrated each scanner according to the manufacturers specifications. But when we had them tested looked at them we found that they were producing different results.”
Even without implementing the color management, the discovery of scanner problems has increased the quality and decreased the costs of scanning. “After discovering and repairing the scanners we are seeing our rescan percentage drop, reports Logsdon. “I can say that it was during the pursuit of process control that our rescan percentage dropped from 10% to 3%. Considering that we make over 7,000 scans a year that is a significant savings.”
Printing Specifications
Brian Lawler is a consultant specializing in color management. According to Lawler, “Color management is part of total quality management. You can’t do color management without quality standards. I can tell during the first conversation with a printer, how difficult it will be to implement color management. In that initial conversation I say let's put a test form on the press and bring the inks up to standard density. If they nod their head I know it will be easy, if they look at me with a puzzled look I know we have a lot of basic work to do first.
Lawler says, “The best example of this problem was when I worked for a web printer in Northern California. They would spend 2-3 hours for press make-readies before every run. When I walked into the pressroom I found that they were getting up to color visually, meaning by eye. I told them we could never implement color management until they started bringing the press up to color using basic press density measurements.”
“So we went to a cabinet in the corner, dusted off the densitometer, ran some test forms and established ink densities.” continues Lawler. “Once we established density standards, time and waste from make-readies dropped significantly. Then they bought a digital proofer (Iris) and created profiles for the IQPro RIP which reduced the time to make proofs from days to hours to make one or two digital proofs.
The Ugly
There are other, more subtle problems that plaque CMS users. For example, some measurement equipment (i.e. densitometers, spectrophotometers) are so old, unreliable and uncalibrated that the measurements they take are just wrong. In the example above Brian Lawler was luckier then I am. All too often after dusting off that old densitometer it is not working right
A more insidious problem is the fact that the importance of process control is not well understood by many. Some dealers tell printers that they do not need to purchase the equipment to print targets and measure the output which shows if the equipment performance is within tolerance. Instead some sell a service in which they visit every 3-6 months and test the performance and recalibrate the system. This may be OK for scanners and monitors but not appropriate for proofers.
The lack of checking and adjusting for equipment drift is one of the reasons why so many companies are struggling in their attempts to match their proof with their press. This is something I have discovered over the last two years as I work with companies struggling to match their large format inkjets with their press. In many of these visits the companies rely on visits to check that their proofers are within tolerances. This is something that should be checked everyday – not 3 or 4 times a year.
Imagine my surprise when I discovered many of these issues plaguing a printer in Oregon. They had some of the top tools including the automated spectrophotometer, Imation and Gretag software and BestColor RIP. In analyzing the workflow I discovered the transmissive densitometer used to check the film was off, making the film used to create the Matchprint off (the final target). In addition, when testing the target the yellow could not achieve satisfactory density, even after calibration. And worst of all the linearization procedure was so cumbersome and time consuming requiring 45 minutes that the staff refused to do it.
After creating a new Matchprint with linear film, replacing the yellow inkjet canister and creating a one shot calibration procedure using individual curves (requiring 10 minutes) the proof matched better and the staff were no longer resistant to linearizing the device every morning. The creation of a fast check of accuracy and correction (calibration) process is one one of the reasons why companies neglect checking and adjusting equipment performance. There are recommended linearization or calibration procedures that can take 45 minutes or longer. Anyone who has ever worked in production, knows if you want process control to be successful you have to be able to create a procedure that takes 20 minutes or less.
The Ultimate Gray Area – Your Press
It is interesting to watch the different ways companies implement color management. Creating profiles for the equipment early in the process such as scanners, digital cameras and monitors is often done by end users. Color management early in the process is typically easier, less expensive, and a good long term solution because the performance drift is less and you don’t need an expensive measuring device such as a spectrophotometer.
Color management later in the process such as in the pressroom is more difficult, expensive and in my experience less reliable, because of the inherent variability in offset printing. That can mean that profiles work great for one day or one week.
However as the press changes its performance over time, that finely tuned profile is no longer valid. With that profile adjusting color in strange and unusual ways it is harder to correct the press then if you had done nothing at all. As a result some people try to adjust the profiles, make testing targets on an ongoing basis in subsequent press runs. However, this constant tweaking results in less reliable and results in less accurate profiles.
This problem is exacerbated by companies that try to optimize press performance. Some companies, with the best of intentions, bring in someone either a consultant or the manufacturer's technician to make the press run as well as possible. Once the press is running as well as possible (optimized or fingerprinted) then targets are printed, measured and profiles created. As discussed earlier, these profiles work well for a while and then over time are no longer accurate because the drift. The only way this optimized performance can be sustained is by adopting a world class maintenance program such as Total Production Maintenance. This is rarely the case however.
Grey balance curves
For the reasons above, applying profiles to the press room is notoriously difficult. A new strategy that I have created and is in testing is utilizing color management profiles for everything except for the pressroom. After years of creating and measuring press sheets after using CMS profiles I am looking for a better way. The strategy I have been testing for a year I call dot gain compensation curves with grey balance adjustments. These curves are applying at the RIP of the imagesetter of high resolution output devices (imagesetters, platesetters) that drive the presses.
Grey balances curves help compensate for the impurities in all inks that results in longer make-ready times. Most desktop applications that convert from RGB to CYMK will translate greys into equal amounts of CYM inks. Depending of which inks you use that will mean that your greys will either be too blue, yellow or red. Creating grey balance curves on your output devices can compensate for the subtle differences in your inks and eliminate the extra 10-15 minutes of make ready time required to adjust the CYM inks to result in grey balance.
The use of dot gain curves on output devices is controversial and for good reason. Most creatives and print customers who perform their own scanning convert the resulting RGB files to CYMK files using a desktop application such as Photoshop. As Photoshop creates the CYMK files it performs a dot gain compensation, typically using a 20% SWOP coated profile. As a result some dot gain compensation has already been applied to the customer's file.
Therefore, if you are going to create an additional curve on the RIP on the imagesetters or platesetters it should be small and subtle, in other words 1-4% for coated stocks on offset presses, 3-6% on uncoated stocks for offset, and 5-10% for uncoated stocks on web presses. However, it's not the dot gain compensation that results in shorter make-ready times it is the small adjustments in these curves which results in slightly different amounts of CYM so that the neutrals are neutral without deviating from your target ink densities such as SNAP, Gracol or SWOP.
Summary
While theory and goals for CMS are admirable, the opinions are mixed because some claim success while others report failure. As discussed in the first article, while there are a myriad reasons why some succeed while others fail, but it is most likely is related to the type of equipment (scanner vs press) as well as the use of process control.
Arguably, the greatest challenge in printing is making the color match better from the proof to the press. However, there are a host of issues that makes using CMS profiles for presses very difficult. One alternative method of improving the color and reducing makereadies on press under review by this author is dot gain curves with grey balance adjustments.
Howard “Howie” Fenton joined NAPL as the senior consultant of digital technology in 2002. Before joining NAPL he was a consultant for GATF and was the editor of a prepress magazine (Pre). As a consultant he audits 35 companies year and as a in house trainer he performs over 100 seminars a year. He has authored five books on: digital printing, scanning, color management, and emerging digital technologies. Got questions? Email HowieAtPre@aol.com.
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