Prime-time for Contone Proofing

Today's improved ink jet technology offers an impressive mix of color accuracy, media versatility, and affordability.

by Jessica Millward, Associate Editor

ALL PROOFS ARE not created equal. Nor should they be. The range of proof requisites varies from printer to printer, and from production stage to production stage. While newly developed digital halftone systems get closer to ultimate color matching (see next month's PrePress article for more details), ink jet-based digital proofing comprises the all-round best solution for many prepress programs. Suppliers' keen interest in developing both drop-on-demand and continuous ink jet devices testifies to contone's strong foothold within the packaging market.

On the spot

In proofing, the chief concern for package printers remains the ability to reproduce spot colors. The reconciliation of digital technology and trademark (often brand-specific) colors is an ongoing process, but one making discernible strides.

As Mark Vanover, marketing director for digital proofing at CreoScitex America relates, "The success of any proofing device to render spot colors is primarily dependent on the RIP technology." He notes CreoScitex's IrisPRINT series of continuous ink jet proofers employs a Pantone-approved workflow that utilizes the wide color gamut ink set to successfully represent a majority of the Pantone color space with a high degree of accuracy.

Another pressing concern facing package printers is determining the image accuracy level demanded by their output. Digital halftone systems yield the greatest image fidelity and most exact halftone reproduction, yet the investment outlay for such precision is not within every budget.

While contone proofing accounts for approximately 35 percent of CreoScitex sales to package printers (65 percent comes from sales of halftone proofing equipment), Vanover stresses the importance of learning your specific needs as well as how different proofing technologies will serve them. "While drop-on-demand, continuous tone proofing has become more widely accepted, correct expectations of users need to be set in regards to what the DOD capabilities are and are not."

At CMM 2001, DuPont Color Proofing Global Packaging Segment Manager Gregg Tashker emphasized the need for the continuing development of various proofing methods. The company has persisted in researching and improving analog, contone, and digital halftone solutions.

Marek Skrzynski, director of graphic development at prepress provider CSW (see below) agrees: "I don't think the key is to re-invent the wheel; it is to use and improve what is already out there."

Contone line-up

DuPont's diverse repertoire of technology was in full force at CMM. Making their debut at Drupa, the Cromalin® Digital iG2 and iG4 continuous flow ink jet proofers employ the GE (Gamut Enhanced) ink and media set designed to expand the range of spot colors produced.

Other features include the latest CromaNet™ Proof Server for color management of most CTP and desktop file formats, as well as compatibility with Cromalin Digital Transfer media, which enables digital proofs to be transferred to almost any substrate to create mock-ups and prototype proofs.

From Imation, the Matchprint ink jet proofing system is available for printers from Canon, Epson, Hewlett-Packard, and larger-format models. The package utilizes Matchprint color RIP software, and provides automatic conversion of custom and corporate colors to CMYK. The color gamut is covered by a Pantone library, unlimited, user-defined custom colors, and up to 12 color separations for proofing.

The drop-on-demand market found a new option in the CreoScitex Iris iPROOF this year. It employs an ink jet proofer with a six-color inking system, the iPROOF Macintosh software digital front end, semi-matte and matte media in 13 in. x 19 in. cut-sheets, and Iris iPROOF dye-based inks.

CSW puts proofer to flexibility test

Because it caters to such a diverse group of package printers, CSW Inc. sought considerable format flexibility when deliberating upon a new proofing solution for its Ludlow, MA-facility. Part of the DieGraphics Group, CSW provides packaging design, proofing, and information technology services, as well as flexographic printing plates, cutting dies, and film separations, to a spectrum of converters in both flexo and offset. The company also does business directly with consumer products companies like Gillette and Bose, and has therefore witnessed the critical nature of proofer capabilities from both sides of the supply chain. After weighing the multitude of equipment options, CSW opted to serve as the North American beta site for Agfa's AgfaJet Sherpa digital ink jet proofing system. Agfa released results of the tests, which were conducted over nearly a year, last month.

The Sherpa family of proofers consists of 24 in., 43 in., 54 in., and 62 in. formats. For the custom colors so vital to packaging, Sherpa features six multi-density inks—CMYK plus a light magenta and a light cyan. These two extra colors soften highlights and make difficult colors easier to match. The system also features advanced ColorTune color management software, while the printer uses an ink-efficient drop-on-demand piezo-electric mechanism.

CSW proofing capabilities run from black/white design proofs to fully color-managed contract proofs. As General Manager Kevin Chop notes, the company also acts as a "control source" by creating press characterizations. Chop immediately recognized Sherpa's value in that aspect: "We create characterizations for a flexographer in New York or a display manufacturer in California, and the Sherpa matches the press output exactly." CSW also uses Sherpa proofs in product photography.

Marek Skrzynski, director of graphic development with CSW, remarks on the productivity value the Sherpa proffers, explaining it outputs approximately four times as fast as some of the other equipment in the CSW prepress facility.

Another considerable asset the Sherpa offers, observes Skrzynski, is its dimensional stability. "Color proofs should provide you with accurate dimensions," he maintains, "because mistakes can cause all sorts of converting problems." This is especially true at CSW, where proofs are often used to produce prototypes.

The piezo electric ink dropping technique employed by the Sherpa has also proved beneficial. Skrzynski points out, "Small and precise droplet size allows for consistent print quality. The piezo electric print head reduces smearing and increases edge definition. With this technology there is no smudging and no color contamination. We are achieving greater color saturation."

With an increasing emphasis being placed on absolute color accuracy, why the decision to invest in a non-laser-powered, non-halftone-focused ink jet device? While the Sherpa does feature screening technology capable of producing a halftone dot for applications up to 100 lpi, Skrzynski believes the halftone element can sometimes be problematic.

"The problem is human-oriented, really," he concedes. "By utilizing color-managed proofing, in addition to dot gain simulation, we introduce artifacts, distinct from the original color separation. Those artifacts come from certain printing imperfections such as ink contamination, ink density, substrate, and other factors. Halftone screening on those proofs will show some artificial dots, possibly causing confusion for even very experienced printers."

On the other hand, Skrzynski attests, screens below 85 lpi create a dot-pattern effect that changes color appearance of the proof. It is necessary to illustrate this to the customer as well.

Ultimately, Skrzynski believes, "Any contract proof should be an accurate simulation of the final printing process, and not a representation of what is on the final film or plate." The final test should be performed by eye, he says, because that is the way end-users will evaluate the product. Chop adds digital halftone doesn't entirely comply with CSW's color management process, and "halftone dots limit the proofer's gamut reproduction capability."

CSW found appropriate color range with the Sherpa's ColorTune Pro color management software, in which six colors generate the ICC-compatible color profiles. The Sherpa matches up to 85 percent of PANTONE colors, because the color-management software maps colors using the Pantone-certified L.a.b library to the available CMYK color space, which includes the light cyan and magenta. The combination of the Sherpa's accuracy and adaptability, according to Chop, "has made a huge difference in the capabilities of our prepress department."