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Imposition proofing

Jul 1, 2002 12:00 AM


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The imposition process has become much more predictable in the past decade. It was once a procedure performed painstakingly by hand; the image assembler and his or her folding dummy, however, have since been eclipsed by the widespread adoption of digital workflows, digital imposition software and large-format output devices.

Even with these improvements, mistakes can still occur. Advertisements may be misplaced, glossary pages forgotten and type corrections overlooked. And, perhaps the most common error, page numbers in the index may no longer match the actual contents. To avoid these issues, most printers still furnish a folded, trimmed and bound imposition proof to their customers as a final point of quality control before plates are made.

For those operations using imagesetters and film, this final proof has traditionally been a blueline (a single-color proof made on DuPont Color Proofing's (Wilmington, DE) ubiquitous blue-and-cream Dylux material). For an increasing number of printers, however, CTP precludes the traditional blueline option. Instead, these shops are outputting digital data directly to a physical proof.

Mirroring recent platesetter developments, choices for imposition proofing are contracting. The remaining devices, however, are expanding in both capabilities and utilization, as large-format digital proofing becomes the norm rather than the exception.

FIRST-GENERATION PLOTTERS

Even before CTP workflows went mainstream, creative printers used roll-fed inkjet plotters for proofing entire press sheets. First-generation devices suffered from low resolution, large droplet sizes, banding and a host of other problems. Nonetheless, the value of making a press-sheet-size proof before generating a complete set of film was readily apparent to large-format-imagesetter owners. When Hewlett-Packard (HP) (Palo Alto, CA) introduced the 750C in 1995, its improved resolution and low price ($7,495) prompted many printers to purchase a plotter for imposition proofing as well as signage, point-of-sale displays and many other applications.

Another important technological innovation occurred in 1996, when ColorSpan (then called LaserMaster) introduced the external-drum DesignWinder proofing device, which offered a smoothness of reproduction superior to the early capstan-driven plotters. It wasn't the first external-drum inkjet imaging device, but the DesignWinder broke new ground with its eight-color inkset. Switching from normal densities of cyan and magenta to lighter densities in highlight areas allowed the DesignWinder to extend gray-level capabilities, increase highlight detail and reduce banding problems. Today, multidensity inksets of six, seven or eight colors have become typical among photo-quality inkjet devices and can also be found on some large-format plotters.

MacDermid Inc. (Eden Prairie, MN) acquired ColorSpan in 2000. Currently the company offers three printer families that can be used for imposition proofing: the high-end DisplayMaker Mach 12 in 42-, 60- and 72-inch widths; DisplayMaker Series XII in 52-, 62- and 72-inch widths; and the entry-level DisplayMaker Esprit 5 in 52-inch, 62-inch and 72-inch widths.

IT'S A CONTRACT PROOF, TOO

The improving color reproduction of today's proofers, inks and papers is enabling some printers to produce an imposed proof that also can be used for color approval with some customers.

“The latest proofers hitting the market are stunningly good,” reports Jeff Wall, production manager, Mahaffeys' Quality Printing (Jackson, MS). “We use the same inkjet device for both our imposition and contract proofing — we have not used a laminate proof since 1998. Our typical customer is a manufacturer with an in-house marketing department that buys its own printing; these people don't have a problem using large-format inkjet for contract proofing, and they're excited by the reduced cost and shorter turnaround.”

One of the original large-format inkjet manufacturers, Encad (San Diego), is poised for resurgence now that it has been acquired by Eastman Kodak Co. (Rochester, NY). Although in recent years Encad has concentrated on the reprographics market, Kodak's involvement may bring a renewed emphasis on Encad's imposition-proofing capabilities. Certainly, shops with multiple output devices should be impressed by the speed of Encad's fastest proofer, the Kodak 5260. Able to image up to 500 sq. ft. per hour through its new dynamic contone technology, this device joins Encad's popular NovaJet model 880 as its flagship large-format products. The NovaJet 880 offers graphics users a wide color gamut along with its ½-inch adjustable-head-height printing capabilities.

While some users find that an off-the-shelf inkjet plotter serves their needs, many eschew the built-in hardware RIPs available for these devices in favor of more sophisticated options from a variety of sources, including BESTcolor USA Inc. (West Chester, OH), CGS (Minneapolis) and KPG (Norwalk, CT). Having recently acquired the respected Imation proofing product line, KPG is helping customers get the most out of devices such as the Epson (Long Beach, CA) Stylus Pro 10000 and HP's DesignJet 5000 CP through its Matchprint RIP software.

“Using KPG's RIP and the Matchprint inkjet paper with an HP 5000 gives us a nice color match to the thermal Matchprints we make on our Creo Spectrum Trendsetter,” says Tim Poole, president of Dome Printing (Sacramento, CA).

Dome customers enjoy the color accuracy the KPG Matchprint RIP provides, and Poole reports that proofs are imaged on single-sided media for several reasons, including pressroom preferences. “One of the problems with two-sided contract proofs is that press operators like a flat proof for color approval,” says Poole. “If you give them a two-sided proof, they'll just cut it apart.”

Some segments of the printing industry are content with a single-sided proof. The packaging industry, for example, has always shown one proof for the front and a second proof for any flexographic printing that might occur inside the carton. For commercial printers, however, printing both sides of the sheet is a typical requirement. For small quantities of imposition proofs, some printers turn to spray-mount as a low-cost solution for backing up one-sided output. While these double-thick proofs are acceptable for certain applications, they can be clumsy to handle.

TWO-SIDED PROOFS

At George Rice and Sons (Los Angeles), the prepress department uses a Creo (Burnaby, BC) Iris 43 Wide inkjet proofer to produce two-sided proofs. Accurately backed-up proofs can be made by carefully loading cut sheets and then letting the Iris's self-centering feature do the rest.

Lee Tran, a prepress technician at George Rice, says the low cost and quick turnaround of these digital imposition proofs makes them popular with clients. “We do a lot of print runs that are Creo Staccato (stochastic) screening, so the stochastic look of the Iris Wide inkjet proofs is not a problem,” notes Tran. “It took a few months to convince the sales force that the Iris proof is the best way to go, but now about 95 percent of our customers ask for them. For a customer that wants to see color breaks in their imposition proof, the Iris is the better, faster option.”

Although the Iris Wide offers a 720-dpi mode, Tran finds the 360-dpi resolution is actually better for an imposition proof. “At 720 dpi, it uses up a lot of ink — the paper absorbs it and then becomes wavy,” says the prepress specialist.

Automatic duplex proofing capability can be bolted on to any existing HP 1000/1050 or HP 5000 plotter, thanks to the SpinJet device from TechSage (Lystrup, Denmark). After launching the SpinJet 1000 at Drupa, TechSage has shipped more than 650 units worldwide since November 2000. SpinJets are available through U.S. reseller TekGraf (Greenville, SC), as well as from Heidelberg (Kennesaw, GA) and Esko-Graphics (Kennesaw).

The SpinJet 5000 debuted at Ipex this past April and is available in both 42- and 60-inch versions. SpinJet hardware is complemented by the SpinFlow software package, which enables duplex proofing from a wide variety of popular RIPs. SpinFlow allows users to define print queues for a variety of back-up scenarios (work and turn, work and tumble, etc.) and provides imposed plate-preview thumbnails. “Adding a SpinJet to our HP 1050 gives us a digital option that is less expensive than outputting composite film just to expose a blueline,” reports Kim Doyle, prepress manager for Tarco Printing (Itasca, IL). “Back-up is accurate to within a millimeter, so it works great for all but the most critical crossovers.”

Doyle adds that the throughput of the HP 1050/SpinJet combination meets Tarco's needs: “Our platesetter images 27 plates per hour, and the SpinJet can keep up with that pace.”

LOOK MA, NO HANDS

Although users have proven that standard-issue devices can be pressed into two-sided service, several vendors offer mechanically modified inkjet proofers with enhanced duplex capabilities. The first such plotter was the Gerber IMPRESS, winner of a 1997 GATF (Sewickely, PA) InterTech technology award. An HP 750c modified with sprocket drives to engage pre-drilled sheets of paper, the IMPRESS was a popular choice among early CTP adopters.

Introduced at Print 01, Agfa's (Wilmington, MA) SherpaMatic expands upon the Sherpa 2 imposition-proofing capabilities. While the Sherpa 2 required manual intervention to flip the sheet, the SherpaMatic 43 features a mechanism for automatic reinsertion.

Agfa expects that most Sherpa 2 owners will echo the enthusiasm of Grant Fritch, director of technology for Walsworth Publishing (Brookfield, MI). “Our seven Sherpa 2s have made thousands of proofs and were a snap fit into our Apogee workflow,” says Fritch. “But our new SherpaMatic 43 provides a faster, hands-free proof from a six-color engine with an even better-quality image.”

To balance the requirements for imposition proofs with the Sherpa's contract-color capabilities, the SherpaMatic 43 can hold two rolls of proofing paper (a two-sided roll for imposition and a one-sided, high-quality roll for contract color).

For shops that want to cut their imposition proofing time to a minimum, Hyphen Asia Pacific (Sydney, Australia) offers the ImpoProof 1050×2. This unique configuration features two HP plotters bolted back-to-back, allowing rolls of paper to be imaged on the top and bottom simultaneously. The ImpoProof has been given a speed boost, and can now output up to 15 duplex proofs per hour at 600 dpi. Hyphen also offers the ImpoProof 1050×1, utilizing a single head with manual reinsertion. Both systems feature the optical camera registration system to ensure accurate backups, and are available in 36-, 42- and 60-inch roll widths.

Henry Wagner, of graphic-arts integrator Cohesion (Westford, MA), emphasizes the front-to-back accuracy provided by the camera registration system. “We've seen that other devices need much more adjusting due to temperature and humidity changes,” he observes. “With the ImpoProof's camera and optical targets, you don't have to worry nearly as much about calibrating the rollers to maintain accurate registration.”

Wagner also cited ImpoProof's workflow benefits: “We've used a number of the dual-head devices from Hyphen. Because they run from 1-bit TIFFs, they're truly workflow independent; the ImpoProof was utilized with a Prinergy workflow in one location, a Rampage workflow in another and a PCC workflow in a third.”

THERMAL IMAGING DEVICES

Inkjet isn't the only digital-imposition option. DuPont's Thermal Dylux material can be exposed by 830-nm thermal imaging devices, including Creo's Trendsetter. Featuring a violet image on a light-green background, Thermal Dylux offers the same two-sided, process-free convenience as its analog predecessor, at an effective resolution of 3600 dpi. It reportedly also exhibits much sharper halftone dot reproduction than a conventional blueline.

The challenge for users is handling the Thermal Dylux material during the loading and unloading process. Since the Trendsetter Spectrum is designed to handle proofing materials right on the drum, it's a natural fit for this workflow. The material can be imaged from the same RIPed file that will eventually image the plate.

Digital-proofing workflows are coming on strong. By providing a faster, cheaper alternative to the traditional film-based blueline, today's leading printers are blazing an all-digital trail to increased efficiency and greater customer satisfaction.

Upgraded RIPs

RIP vendors have their hands full trying to keep up with the quick pace of product innovation in the inkjet marketplace. BESTcolor USA (West Chester, OH) has recently upgraded its Colorproof and Screenproof software packages to enhance compatibility with the newest Stylus Pro 7600 and 9600 printers from Epson (Long Beach, CA). In addition to the new MicroPiezo DX3 high-resolution printheads, Epson's 7600 and 9600 boast a new pigmented seven-color inkset called UltraChrome. Featuring yellow, two shades of magenta, and cyan, as well as three types of black ink, the larger UltraChrome gamut is complemented by color-management products configured for the graphic-arts industry, such as BEST's Colorproof RIP.

“BESTcolor has a close relationship with Epson, Hewlett-Packard (HP) (Palo Alto, CA) and other manufacturers,” says Mark Geeves, president of Bestcolor USA. “We've contributed a lot of information to Epson about what we think is needed for inks in the graphic-arts market. The key to proofing is stability and consistency — we believe that the stability of the new UltraChrome inks combined with the correct high-quality paper will provide exceptional results.”

Epson has launched seven new wide-format papers for its Stylus Pro printers, including Commercial Semimatte. The surface finish simulates typical commercial-printing applications, such as brochures, book covers and posters.