By Dr. Abhay Sharma, Ryerson University
Expanded gamut printing is all the rage, but does it work and what do you have to look out for? Ryerson University has just published a report based on a series of extensive tests using commercial color management systems to process and print test forms containing PANTONE spot colors. The full report—Ryerson University Expanded Gamut Study 2019—Evaluation of Spot Color Reproduction in Multicolor Printing—is available as a free download.
Expanding the Gamut
Expanded color gamut (ECG) printing is a new approach in color reproduction that expands the color gamut of conventional CMYK printing processes via the use of additional colorants, such as Orange, Green, and Violet (OGV) inks. While expanded gamut printing can be used for images and commercial printing, the biggest and most immediate ROI is in spot colors for labels and package printing. A participating vendor in the study, Barbara Braun-Metz, CEO, ColorLogic GmbH, put it succinctly: “In essence, an expanded gamut system can avoid the overhead of printing with spot color inks, and replace them with a fixed set of expanded gamut inks while still achieving the customer's requested color.”
The benefits of expanded gamut printing may include an expanded color gamut, ability to reproduce a large number of spot colors, better accuracy on press, ability to gang jobs, fewer ink changes and washups, environmentally friendly solutions, etc.
The Ryerson University ECG Shoot Out
The Ryerson University Expanded Gamut Study used a “shoot out” format that evaluated solutions for expanded gamut color printing from Alwan, CGS ORIS, ColorLogic, EFI, GMG Color, Heidelberg, HP, Kodak, Hybrid Software, and X-Rite.
The project was proposed to vendors at an ad hoc meeting during the Printing Industries of America Color Conference, held in San Diego, January 12 to 15, 2019, and was subsequently conducted using two, CMYKOGV printing systems: an Epson SureColor P9000 inkjet printer/proofer at Ryerson University, Toronto, and an HP Indigo 7900 at HP’s Graphics Experience Center, Alpharetta, Ga. Printing, measurement, and analysis was conducted from January to June, 2019.
In an ingenious experiment, the whole PANTONE+ Solid Coated spot color library, consisting of 1,846 spot colors, was printed on the Epson P9000 and HP Indigo 7900, using CMYKOGV colorants. It is shown that the solutions are able to reproduce 89–94% of the spot colors on the Epson P9000 inkjet printer and 77–87% of the library on the Indigo 7900, both to < 2 CIEDE2000 (a typical tolerance in label and packaging work). The implications of the study are profound: as the systems were able to reproduce most of the spot color library, it is possible today to dispense with the traditional approach to spot colors and adopt an expanded gamut solution instead.
The number of color patches in expanded gamut characterization test charts is still an area of proprietary, nonstandardized working practice; there is no standardized IT8.7/4 as used in CMYK printing. In narrow-web flexography, there are real estate limitations and too many patches are a printing and measuring nightmare. The study found that vendors use proprietary test charts in which the number of patches ranged from 875, the lowest number, for Alwan to 3,528 (ColorLogic) and 3,536 (Kodak).
There are many different colorant combinations that can make the same color in expanded gamut printing. There is considerable redundancy in creating an ink build—think of the GCR black channel, but now with seven colors! Expanded gamut printing can have ink builds that are more stable on press, the new primaries can be nearer to the color to be reproduced, so a small drift of ink density on press is less noticeable, leading to more accurate printing and easier process control.
The separations and ink recipe of each system were evaluated. For example, for PANTONE 2433 C. Alwan, GCS ORIS, and ColorLogic create a very similar build, with emphasis on Orange and Yellow for what is an orange spot color. Kodak and GMG Color create a CMYK-only build with no expanded gamut colorants. Heidelberg violated a golden rule of limiting the build to three channels, and used five channels, but with the least TAC. It is interesting to note that all of the above builds were accurate to CIEDE2000 <1, so all of these builds essentially created the same color when printed.
In addition to the technical tests, we conducted a product review of the features and technical functionality of each system. There are some excellent products in this area, but there are also some poor interfaces, programs that crashed during our demo, and obsolete software features that should be addressed such as making separate “proofer” and “separation” ICC profiles.
Pantone and Adobe provide everyday commercial tools for expanded jobs and workflows. The study identified some issues with products from these companies that could confuse a less skilled user in a busy press shop.
Implications for End Users
The end user may not have the time (or expertise) to evaluate the technical performance of complex ECG systems. In this situation, a university-led study provides non-biased, independent, reliable information and thereby creates an opportunity for more users to consider this emerging color technology.
The findings show that expanded gamut printing can replace cumbersome conventional spot color workflows creating considerable savings and advantages, especially for label and packaging printers. The conclusion of the study is that expanded gamut solutions for spot color printing produce totally acceptable results, expanded gamut printing is ready, here and now. Advisor to the study, Marc Levine, Director, Enterprise Print Quality for Schawk Inc., notes that “many printers want to move to ECG but face obstacles related to technology unknowns. With this study, we seek to remove some of those unknowns so that that printers who wish to move ahead with ECG are more empowered to do so....”
Plan Your Tradeshow Visits
If you are doing the trade show circuit this Fall, some questions the packaging printer may ask are related to cost: do I have to buy the whole server solution or just an expanded gamut piece of software? Other questions to ask are, is the vendor investing in ongoing development and investment in color technology, do they work to standards such as ICC and M1 measurement mode, and, very importantly, does the product support color-accurate soft proofing?
Get up to speed and read the full in-depth research in the Ryerson University Expanded Gamut Study 2019 get your free download today. For further questions contact the author of the report, Dr. Abhay Sharma, Ryerson University, Toronto.
Dr. Abhay Sharma is a Professor in the School of Graphic Communications Management at Ryerson University. He can be reached at [email protected].
Discussion
By Robert Chung on Sep 12, 2019
Abhay, I read your report with pleasure.
I may be nitpicking -- the two axises in the CRF graph (Figure 5 and 6) in your report are transposed.
To explain, we typically construct a Delta E histogram using the value (Delta E) as the x-axis and frequency or count as the y-axis. In a CRF plot, we simply convert frequency (F) into cumulative relative frequency (CRF). We do not transpose the two coordinates. Agree?
Bob
By Abhay Sharma on Sep 13, 2019
Dear Bob
You and I teach/taught our students about dependent vs independent variables when plotting a graph. I had plotted Figure 5 and 6, the way you describe, then changed it! But now that you explain it so clearly, I have to agree with your observation. I will transpose the axis as per your suggestion, for journal publication.
Many thanks, Abhay
Discussion
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