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Digital Proofing--Halftone-hungry Prepress Proofers

April 1998

What's more, United Litho found that the digital halftone proofing device fit in nicely with the production cycle of its Agfa Galileo. "We decided the two technologies complemented one another very well in our prepress environment," Richards reports. "Together, they are doing beautiful work."

Question: Is United Lithograph's experience with digital halftone proofing typical?

Betty LaBaugh, marketing and communications manager for Polaroid Graphics Imaging, offers a PolaProof perspective.

"United Lithograph is typical of how commercial printers who realize the need for digital halftone proofing react—they achieve the 'light bulb' when they begin planning for the implementation of a CTP workflow in their shops."

United Lithograph purchased its PolaProof device after beta was complete—and today reports that more than 90 percent of its jobs are proofed on the PolaProof, which replaced two analog proofing systems.

"PolaProof owners, such as United Lithograph, use the digital halftone proofer for a variety of proofing applications, including loose color from the digital photography studio and scanning department, as well as combined proofs of complete jobs," LaBaugh reports.

Sandy Fuhs, marketing manager at Presstek, makers of the PEARLhdp digital halftone proofer, has a theory on the growth and current status of digital halftone proofing, at least from Presstek's vantage.

"Presstek had been feeling the pain of not having an affordable, contract-quality halftone, digital proof since 1991, when we introduced our first direct imaging press," Fuhs states, with a hint of lightheartedness. "When Imation came to us in 1996 to assist with the development of a thermal, digital proof, I knew all of that clean, wholesome living had finally paid off."

Currently, Presstek has three beta sites installed for the Presstek PEARLhdp proofer running Imation Matchprint Laser Proof materials. While all of these sites are under wraps (each signed non-disclosure agreements), Presstek and Imation are running each site at full tilt.

PEARLhdp is a digital halftone proofing device that has a direct digital link to a variety of prepress systems through a process known as PEARL imaging. It is an external, laser diode-based, thermal imager connected to the prepress area via the PEARLrip workstation.

The PEARLhdp uses Imation's Matchprint Laser Proof materials to produce what is claimed to be a pressroom-accepted, high-resolution, screened contract proof. Imation's Matchprint Laser Proof is a repeatable color proofing technology that relies on the same class of pigments and colors as conventional film-based Matchprint III. An MLP halftone proof is thermally imaged from a digital file.

It is imaged by a technique called Laser Induced Film Transfer (LIFT). The proofs are non-photographic, require no chemical processing and are insensitive to normal daylight. The proofing materials consist of a coated receptor, four-color donor sheets (CMYK exposed individually) and a base paper sheet that receives the positive, color images from the receptor to complete a proof that looks like a printed sheet.

"We work in a manufacturing industry, in which we need to have appropriate checks and balances at every stage," Presstek's Fuhs asserts. "The cost for digital prepress and press time has elevated to a point that close-enough color is a costly, non-manufacturing solution. Ask any printer who had to eat the cost of a press run due to an unattainable match between the 'pleasing color' and ink-on-paper."

By eliminating the majority of manual processes involved with production, such as film exposure, processing, manual register of individual separations and proof processing, digital halftone proofing allows prepress departments to shine.

If that's the case, John D. Lucas Printing must be beaming, as Ed Hartman, manager of electronic prepress, reports.

"At Lucas, digital halftone proofing is firmly in place with our TrueRite from Screen (USA). As far as I'm concerned, there isn't another digital halftone proofer," Hartman contends.

Screen's TrueRite is a 4,000 dpi halftone proofer that consists of the TC-P1080 exposer and TP-80 laminator. The unit can output proofs on actual stocks.

What will keep John D. Lucas Printing halftone hungry? Hartman is quick to respond. "Repeatability and reliability—that's what a digital proof must deliver in a direct-to-plate environment," he explains.

"Digital halftone proofing offers functionality," Hartman continues. "With the Screen proofer, we can use the same RIP for the digital proof as we do for other output devices. We don't have to go to an off-line device, or to film or plate. With digital halftone proofing, John D. Lucas Printing eliminates an entire generation from the proofing process, while offering the exact same resolution and dot structure on the proof as predicted for the plates that will deliver the finished product."

Hartman advises any commercial printing firm interested in digital halftone proofing to research the market and select a digital halftone proofer that wins its confidence based on technical merits and performance.

"You have to really believe in the equipment you're using, especially in a direct-to-plate environment," Hartman advises. "There is no room for errors, big or small, in digital proofing."

Eliminating All Errors
Creo Products is currently beta testing its newly introduced Spectrum proofer, a standalone, large-format digital halftone proofing device dedicated to imaging only proofing material, delivering four-page proofs in under 30 minutes.

Since the Spectrum proofer and all of Creo's platemaking devices, including the Trendsetter Spectrum, share the same imaging technology and optical registration system, they can work jointly to provide proofs and plates that have common characteristics, such as screening, resolution and sharpness.

What is Creo's forecast for digital halftone proofing technologies? Creo recognizes that halftone proofing is one of the most critical components to the successful implementation of CTP, reports Steve Prescesky, proofing product manager at Creo.

The Trendsetter Spectrum utilizes Creo's thermal imaging technology to image Matchprint Laser Proof materials. Recently, Creo announced the introduction of Spectrum Highlight, a standalone halftone proofer dedicated to imaging only proofing materials. The Spectrum Highlight offers a flexible range of media sizes, including two-, four- and eight-page formats.

"Spectrum offers a high level of automation and completes a full proof cycle without the need for operator intervention," explains Prescesky. "The system automatically ensures exact color-to-color registration with increased proof consistency through reduced process variability."

Landscape in Minneapolis—a commercial and packaging trade shop—is beta testing the Trendsetter Spectrum and is very enthusiastic about halftone proofing.

"Based on feedback from our customers, we knew that offering digital halftone proofs that perfectly match the plates would give us a competitive advantage," reveals Tom Forsythe, Landscape president. "For us, the Spectrum Matchprint Laser Proofs are indistinguishable from conventional Matchprint—making the conversion to digital proofing effortless in the pressroom."

Quite a conversion. Let's pay close attention to which manufacturers make it the most effortless.

—Marie Ranoia Alonso

Polaroid's Platform:
LAT Technology& Halftone Proofing

Betty LaBaugh, marketing and communications manager at Polaroid Graphics Imaging, explains how the makers of PolaProof harnessed and patented Laser Ablation Transfer (LAT) to harness halftone proofing.

Polaroid had been working on a thermal plate technology for some time. However, when the company researched the market on what was required to enable the adoption of CTP, Polaroid found that the weakest links in the move to an all-digital workflow were stable and repeatable continuous-tone proofing, high-quality direct digital halftone proofing and a low-cost, efficient, high-powered laser system.

Polaroid set out to focus on Laser Ablation Transfer technology—the high-speed transfer of imaging material from a donor to a receiver, as is the case with PolaProof, which directly transfers actual printing ink pigments to printing stock.

Polaroid's LAT is a clean ablation technology, which transfers the material directly to the printing stock. Polaroid also provides for the implementation of LAT imaging in other devices from hardware manufacturers by OEMing its Fiber Laser.

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