Hi-Fi Color

The popularity of color printing has turned CMYK reproduction into a commodity, with customer expectations influenced by the vivid graphics of uncalibrated office copiers and desktop inkjet printers. In a world where even the fax machine can spit out a color photograph, it is increasingly difficult for printing companies to distinguish their capabilities from this onslaught of “pleasing color” devices.

Brighter colors and more accurate reproduction may hold the key to differentiation for high-quality shops, which can now choose from a variety of commercialized approaches to high-fidelity or “hi-fi” color. Typically based on five- or six-color ink combinations, these systems claim to provide a noticeably greater range of colors (gamut) than the standard yellow, magenta, cyan and black process colors.

Expanded gamut ink sets have been used commercially for more than 40 years; many give credit to Hallmark Cards for pioneering the use of fluorescent primaries and additional inks as early as 1962. Combining hot pink and light cyan with modified CMYK inks helped Hallmark create the eye-catching Valentine's Day hearts and holiday candy canes that have made the Kansas City publisher a huge success.

Hallmark's research into this six-color ink set (one of its many proprietary formulas) revealed a 50% increase in gamut when compared to standard four-color process, although as researcher Karl Guyler notes, “There are a few colors that can be best printed with only four.” Hallmark's CcMPYK approach differs from most other hi-fi systems by extending print's tonal range in the highlights; adding fluorescence to the pink allows the color to “pop,” even on uncoated or recycled stocks.

While the increased gamut from additional colors can be scientifically proven, some users are still waiting for customer interest to materialize. When Cascade Printing (a division of Core Communications) in Corvallis, OR, upgraded to a new Komori sheetfed press, hopes were high that expanded gamut inks could help to distinguish it from other printers in the region. “We bought a six-color press because it would let us offer Hexachrome printing,” says Ed Rettig, Core's president. “Since then, we've produced a few projects that looked really sharp, but our clients just haven't been that interested,” he notes. “Most of our work is still four-color with an occasional spot, so we typically leave the first unit empty and let the dry blanket pick the lint off the sheets.”

This lack of demand from the design community may lead print providers to wonder if an expanded gamut is worth the investment in special inks, software and training. Will hi-fi color capture the hearts and minds of print buyers, or is this just another “workflow concept,” like stochastic screening or computer-to-plate?

Yes, yes and yes, according to Kodak's Gordon Pritchard, who contends that it takes a combination of all three technologies to produce optimal results. The Spotless Printing Solution employs the high-resolution laser of Kodak's Trendsetter CTP device in conjunction with specialized variations of its Staccato FM screening process to simulate a broad range of spot colors. Just released, the Spotless Printing Solution v.2 is compatible with user-defined four-, five-, six- and seven-color ink sets.

Kodak Prinergy systems can automatically convert PDF documents into Spotless Color projects. But despite these advantages, Kodak is aware that widespread adoption won't occur overnight. “Success with Spotless printing demands that the printer take the marketing initiative,” notes Pritchard. “It's a matter of solving their customers' print issues, rather than just waiting for print buyers to ask for it.”

Stochastic screening is also the key to a new expanded gamut process known as FMsix (for which Kodak's Staccato technique is specifically recommended). First shown at Ipex 2002, this process uses six colors: CMYK plus FMsix's special formulations of orange in combination with either blue or green. Logos, text and other graphic elements can be preprocessed to utilize the FMsix system; photographic images are rendered using only the standard process colors, not the six-color process. The FMsix technology is licensed by PrinTech Systems B.V., headquartered in the Netherlands.

Opaltone Digital Color is a fully integrated reproduction system with an infrastructure that includes multicolor separation software, editing/graphic assembly software, digital/analog proofing and a standard seven-color process (CMYK/RGB) ink set that supports conventional and stochastic screening. Opaltone claims to both increase gamut and allow photographic images to be printed without black ink. By overprinting RGB in the shadow areas rather than using black, printers can run the higher densities desired for black text and line art. Files can be prepared through an Adobe Photoshop plug-in or calculated within specialized programs, such as Artwork Systems' ArtPro or Esko's PackEdge.

Pantone's Hexachrome may be the most widely used ink set for expanded gamut printing, featuring fluorescent orange and green in combination with customized CMYK inks. Introduced in 1994, Hexachrome's longevity has translated into widespread support among prepress vendors and design applications. QuarkXPress can convert RGB images into Hexachrome separations on the fly; for Adobe's Creative Suite, Pantone supplies plug-ins to work with Photoshop and Illustrator. Pantone's ColorSuite for Hexachrome includes printed swatchbooks (both the solid-in-Hexachrome guide as well as Pantone's color bridge solid-to-process guide), Hexware software plug-ins and a six-color test form in print and digital formats.

As prepress workflow systems grow more sophisticated, the power of color management is expanding to encompass device-n color separation. A term used to define color systems other than RGB or CMYK, device-n (also called n-color) allows RGB image data to be reproduced with colors other than (or in addition to) the standard process set. Agfa's Alterno, Screen's Spektacolor and Esko's InkWizard all are capable of rendering output based on user-defined ink palettes. Gretag Macbeth's ProfileMaker 5 Publish Plus (now an X-Rite product) can create multicolor separation profiles for color-managed RIPs, or can be used in conjunction with PM5 Multicolor Plug-ins for Adobe Photoshop to create pre-separated Desktop Color Separated (DCS) files.

Digital press manufacturers are also embracing the power of expanded gamut, as evidenced by products from HP (Indigo), Kodak (NexPress), Océ and Punch Graphix (Xeikon). These presses feature more than four colors of toner, paired with digital front ends that automatically convert incoming projects to the enhanced color space.

As proven by the cover of this month's Graphic Arts Monthly, HP's Indigo press can provide a wide gamut through its six-color IndiChrome process. (See related story on p.66.) Combining CMYK imaging oils with orange and violet increases the number of possible colors; utilizing the Indigo's seventh unit for a customer-specified spot color increases the possibilities even further. HP's ElectroInk mixing system is Pantone-certified, allowing PMS colors to be created by mixing reflex blue, green, rhodamine red, bright yellow and transparent colorants in addition to orange, violet and CMYK.

Kodak's Intelligent Color, Coating and Glossing Solutions include the ability to fill the NexPress fifth printing unit with red, green or blue dry ink to expand the printer's available color gamut. Alternatively, a protective layer of clear dry ink “varnish” also can be applied, whose gloss can be enhanced by the near-line NexGlosser unit. Automatic color management and optional image enhancement are provided by the NexStation front end.

Océ provides two high-volume, high-speed production presses based on a seven-color imaging system. The Color Production Tandem series CPT 60 and CPT 90 printers are self-calibrating systems intended for high-quality color output at up to 92 ppm. Driven by EFI's 1000C color server, Océ's developer-free CMYK toners are augmented with red, green and blue for consistent output that approaches lithographic quality.

Xeikon offers a five-over-five configuration for duplexing, roll-fed digital presses. Its flagship 5000 model produces CMYK output in combination with a fifth color station that can be used for spot colors. Available toners include standard blue, violet, red, orange and green or custom colors created upon request. The fifth color station also can utilize special toners to enable security printing, check manufacturing and other specialties.

The traditional approach to preparing hi-fi color projects relies on a vendor-supplied Adobe Photoshop plug-in that converts images into the multi-channel DCS format, while enhanced “spot” colors are selected from a custom swatchbook within QuarkXPress, InDesign or Illustrator. A new approach automatically converts content using a multi-channel color management profile—but this can only occur if the RIP is capable of “n-color” separations.

Seeing an appreciable improvement in image quality requires a wide-gamut original, so all forms of hi-fi color work best with RGB images. (An image that has been converted to CMYK already has a constricted gamut that will not exploit your additional colors.) The new generation of n-color RIPs can use Pantone's L*A*B spot color definitions (available in Adobe InDesign CS2), allowing these systems to automatically generate five-, six- or seven-color screen builds.

Not all expanded gamut systems convert both bitmap and vector content: PrinTech's FMsix concentrates solely on spot-color conversions, preferring to handle photographic images through the usual four-color reproduction. Other vendors generate multi-channel images through an Adobe Photoshop plug-in, but Opaltone also provides digital color palettes for Adobe's Illustrator and Indesign, QuarkXPress, ArtPro and PackEdge.

Pantone continues to develop its Hexware plug-ins for Photoshop and Illustrator, including a recent update for improved CS2 compatibility. New color bridge libraries and six-channel output capability come standard with the latest version of QuarkXPress, which still is the only page-layout application with built-in Hex support.

Printers heavily invested in 4-color presses will be thrilled to hear that brighter colors and a wider gamut can be realized through improved CMYK inks. Several ink manufacturers can create cleaner inks whose color absorption characteristics are more finely tuned to reduce grayness (contamination from non-primary colors). But cleaner pigments tend to be more expensive, so it's a cost trade-off. “Improved trapping between inks can also help broaden the range of printable colors,” notes Danny Rich, senior color physicist at Sun Chemical.

At customer request, the Flint Group developed a proprietary system that uses stochastic screening and an improved CMYK ink set. Designed for sheetfed presses but now available for web offset, the inks feature increased transparency and improved trapping. The extra gamut “helps make sure that what consumers see in the catalog matches the real-life product,” says Rod Balmer, Flint's global director of sheetfed R&D.

www. graphics.kodak.com, fmsix.com, opaltone.com, pantone.com, hp.com, oceusa.com and xeikon.com