GRACoL 7: What’s
the big deal? What is GRACoL? GRACoL was created in 1966 by a graphics arts task force that was formed by the Graphic Communications Association (GCA). The initiative to create industry standards was supported by the International Prepress Association, a national traded association for prepress professionals, and Graphic Arts Technical Foundation, the technical foundation that performed the bulk of research and technology for the printing industry. GATF merged with Printing Industries of America in 1999 to form PIA/GATF. In past versions, these guidelines consisted of recommendations for solid ink densities and dot gain characteristics. Although these standards are helpful and are used in a number of pressrooms, they are not bulletproof. For example, because of different inks, press characteristics and papers mean that even though hitting the same densities and dot gain in different plants, color does not match and is not standard. To put it more bluntly, while it was a good rough guideline for a printing plant, it did not give a common color match. While the previous versions of GRACoL were based primarily on TVI (dot gain) and solid ink densities, GRACoL 7 is based on an unambiguous definition of a neutral gray in the midtones. This process of calibrating based on neutral gray is referred to as the G7 process. Although it is associated with GRACoL 7 it is not the same thing. While GRACoL 7 is a standard, G7 is a process that could easily be applied to other standards such as SWOP or SNAP. Many people who learn about the G7 process say it reminds them of System Brunner, an established press calibration technique that relies on LAB values and contrast rather than dot gain and solid ink densities. It is true that G7 takes a very different approach. The reason for basing the measurements on LAB rather than TVI is simple. Every press out there has a number of variables. Among these are differing inks and different paper, and different print conditions. For the same reason that an Epson cannot match a press simply based on density, one press can often not match another. Rather than being a set of specifications or densities to run a press to G7 is a process by which an offset press or proofing system can be calibrated to match the GRACoL 7 standard. What is different about G7 “Having a standard based on visual appearance...heck, having a standard at all is worth it,” Bayne said. “A print standard has been lacking in this country for a long time. With the advent of CTP, it has been even more of a can of worms (i.e. do you go linear with your plates or mimic analog printing with a bump curve in the plates). Since the G7 process is based on visual appearance, projects that need to be printed using different printing processes can effectively look the same when printed using these different print processes (such as. web vs. sheetfed, vs. flexo, vs. gravure). “This is not how we set plate and film curves in the past,” Bayne said. “If a web press was gaining 25 percent in the midtones, we assumed that was where it should be printing as web presses inherently gain more than sheetfed presses. And if a sheetfed press was gaining 18 percent, we justified this amount of gain on the fact that sheetfed presses were capable of lower TVI than web presses. “We either separated differently for the two processes or just left things as is, causing a different visual appearance between the two printing processes. Also with the GRACoL Master Printer Qualification program, print buyers and specifiers will soon be able to search the GRACoL Web site (www.gracol.org) for printers who have been qualified by a GRACoL Certified Expert as adhering to the G7 GRACoL process. I believe this process is a necessity for the future of printing in the U.S. Content creators and print specifiers will continue to demand higher standards between different printing processes. GRACoL and the G7 process will be the means to this end, providing the potential for consistency between printing processes,” Bayne said. “Printers who adopt this process early will undoubtedly gain a competitive edge in a crowded market.” A simplified summary of the G7 process is as follows: A press run is performed using raw and uncalibrated plates. The press is run to the numbers and a press is driven toward a perfect neutral gray using lab values and solid ink density. The press sheet is analyzed for CMY and K curves, and for the neutral gray (50, 40, 40). (This can be done using software or by hand plotting the curves on graph paper.) If needed adjustments are made to the CMY curves and the K curves to make them fall within tolerances required for GRACoL. Note that these moves are to CMY as a single unit, not to each plate curve. A qualifying pressrun is performed after any required adjustments have been made. During this run the neutral is again adjusted by moving the solid ink densities until they are within tolerance. During this process TVI is used more as a diagnostic to detect press issues than as part of the G7 process. The G7 process can also be used to move a proofer to the same specification so that that proofer matches GRACoL 7 as well. This works especially well on dot proofers such as the Kodak Approval or Fuji Finalproof. What about the GRACoL 7 process? How
is it different from GRACoL 6 “One of the critical success factors in the growth of any standard is its visibility to the industry which it is built,” said Mark Levine, a product manager for X-Rite, a leading vendor of color specification tools for the printing industry. “There are many methodologies in use today that have not been adopted by larger masses simply due to the fact that there has been no driving force behind selling these methodologies. “Certain components of workflow have been accepted, such as TVI, however, most standardized practice in commercial offset printing is typically grouped under the SWOP umbrella. With the emergence of G7, GRACoL has done a great job at creating visibility around this new printing paradigm,” Levine said. “The new G7 workflow issues in an age of appearance to the pressroom. Historically, ink on press has been managed much like you would service the tires on your car. You probably take a peek before to hop in to see if your tire pressure is low. If so, you go to the gas station, get out the tire gauge, and inflate to the recommended pressure. Four inks, four tires. While the G7 driver is also checking air pressure, they are more interested in the ride. Levine said a G7 customer might air-up, head out for a spin, and find that their car — despite having the correct tire pressure — still does not drive straight. In this way, the G7 driver is looking for more than just TVI problems. “They are looking for printability issues as a whole,” he said. “By choosing to target the scale of gray balance and colorimetrically managing it, G7 helps users better identify and control how a press ‘drives,’ rather than just seeing if one of its tires is low on air. In some cases, these two things may be the same. In some cases, they may not.” From the customer perspective Rob explains, “We were looking to free our creative team from the narrow and confining gamut offered by SWOP as well as a standard that better leverages the capabilities offered by today’s output devices. Both of these concerns were easily addressed by making the transition to the GRACoL standard.” How are printers responding to GRACoL?
“I’ve been working with them for about a year now bringing them slowly into the 21st century with International Color Consortium-based color management. They were looking at GRACoL 6 when we started profiling their presses and proofers. It was a no-brainer for me to bring up the topic of GRACoL 7 and the Master Printer program. The Master Printer program falls right in line with their marketing direction to differentiate themselves from the competition,” he said. “They are going to start talking to their key customers about the benefits of G7 and advise their customers to only do business with GRACoL Master Printers.” More information |
