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DIGITAL COLOR PROOFING -- Right on the Dot

March 2002
BY MARK SMITH


For more than two decades, the conversion of printing to digital processes has seemed to keep the industry in a constant state of change. At the same time, though, the diversity in print processes, providers and customers means technologies get adopted at different rates across the spectrum of users.

This staggered adoption cycle keeps the industry revisiting the same issues for a time, as each wave of new buyers comes along. Earlier adopters, meanwhile, can be left with a feeling of been there, done that—having bought a now-obsolete piece of equipment, in some cases.

Digital color proofing is a prime example, particularly in regard to the question of whether a contract color proof needs to show a halftone dot or not. This issue cropped up when the first digital proofing systems were introduced, since they were continuous-tone devices. The pro-dot argument was cited as a reason for sticking with analog proofs. The debate evolved with the introduction of digital halftone proofers some years later, but the basic arguments remained largely the same.

With both digital halftone and continuous-tone proofers now firmly established in the market, the growing trend toward adoption of a computer-to-plate workflow has raised the stakes in proofing. Rather than assuming the same arguments apply, it seemed like a good time to check with some digital halftone proofing system users to see if there's been any change in attitude about the requirements for a contract color proof.

Customer expectations continue to drive the digital proofing capabilities installed by Color + Graphics in Cerritos, CA, reports Danny Bishop, operations manager. The shop does fine-art reproductions and high-end commercial work, with prepress, printing (on three six-color sheeted presses) and some finishing handled in-house. It has progressed toward an all-digital workflow in phases, starting with eight-up imagesetting two years ago, digital color proofing a year later and now it is completing the installation of a CTP system.

The printer made the move to digital proofing with the simultaneous installation of a FinalProof thermal halftone unit and a continuous-tone PictroProof device, both from Fuji Photo Film U.S.A. Bishop says the shop needs a high-end halftone proof "in order to simulate printing with a dot at the quality we, and our clients, expect. Our customers have actually asked for proofs with dots," he notes.

Seeing a Pattern

Continuous-tone proofers can come very close to matching the color and quality of thermal halftone technology, but they come up a little short in their representations of pastels, neutral grays and vignettes, Bishop says. The ability to predict moiré also is a big reason to have a dot, and so is showing banding, he adds.

The majority of Color + Graphics' work requires a halftone proof, the operations manager says, but he has seen clients become more accepting of continuous-tone proofs for type corrections or small moves in solid colors.

"We show clients a FinalProof as the first proof to get color right from the start," Bishop explains. "There is some work that only gets a PictroProof, including the ads we send out and more cost-sensitive jobs that are just two-color or simple four-color work. And, about 15 to 20 percent stays in the analog world because we do a lot of spot-color jobs.

"Every proof we make is labeled: analog, FinalProof or PictroProof. We do that to let clients—and everybody here—know what level of match to press they can expect," Bishop says. "We match all of our proofers to the press. We try to fingerprint our presses and calibrate our output devices every six months, starting from the press and working back."

Quality Graphics Center, in Roselle, NJ, recently changed digital color proofing systems, but elected to stay with a halftone solution.

"Our customers asked to still see a dot because they are concerned about subject moiré in things like fabric, in particular," notes Darren Yeats, general manager. "Our clients like a very sharp scan to capture image detail, but that tends to increase the possibility of subject moiré."

The company is a general commercial printer that does high-end color work primarily for the ad agency market. Almost all of its prepress work is for jobs printed internally on two six-color, 40˝ presses and two smaller two-color machines. Quality Graphics converted to an all-digital workflow, including CTP, nearly three years ago. However, it switched to using two Polaroid PolaProof digital halftone proofers only about six months ago.

The shop's workhorse is the automated Prediction model, but it also has the bigger, manual Gold unit to produce larger proofs, serve as a backup and provide more capacity, according to Yeats. The devices are color matched and calibrated, he continues, and can be driven by the identical front end (RIPs, trapping and screening) to Quality's CTP system. Along with the other advantages of halftone proofers, the general manager values the proofers' ability to use some special colors and metallics, as well as image a clear overlay to represent a spot varnish or show a die rule.

At the same time, though, the print shop has maintained the capability to make an analog proof, Yeats notes. "We still can have a client come in with a digital proof and file from an independent prep house. That digital proof will be calibrated to who knows what target, so when we make a digital proof here it may not look anything like the digital proof the client has already bought and paid for. They expect us to fix the file, at our cost, to match the proof that they've already purchased.

"In response, we'll run film to make a Matchprint to show them that the problem is with the file. Matchprint is like law to print buyers," the shop manager continues. "Once they see that, they're willing to pay us to make the necessary changes."

From his perspective as vice president, prepress operations, at The Hennegan Co. in Florence, KY, Mike Fleury sees room for digital halftone and continuous-tone proofing workflows in the industry. However, he believes printers and print buyers decide what level of proof quality they require and then stick with it.

"We created an expectation of seeing dots in proofs during the analog days, and the quality demands of our customers dictate that we stay with a halftone solution," Fleury says. "The cost of a proof is a factor in what we use, but reliability on-press is a bigger concern for us."

The important trend Fleury sees in the industry is a move toward a more color-managed workflow in order to maximize the accuracy of proofs to press. Shops are under pressure to streamline their workflows and effectively manage color throughout the entire production process, he asserts.

"This tends to mean you are going to pick one color proofing solution to achieve that goal. Shops can't afford to have two or three proofing solutions to satisfy two or three flavors of customers."

The Hennegan Co. has chosen the Kodak Approval XP4 system from Kodak Polychrome Graphics as its primary color proofing solution, Fleury says. It also has several wide-format HP 8550 digital proofers for outputting color bluelines, but it doesn't run those proofs on-press, he notes.

The company doesn't use any type of interim color proofing, the prepress exec adds. "Any time they get a proof from Hennegan, our customers expect to be able to say 'go' and have the job print based on what they see. We have to be on our game from the start, which is why we've introduced color management into our processes. From our first-off scans through to our Approval proofs, we can send work off to customers with confidence in the color."

The ability of a digital proofer to support a color-managed workflow is a more important concern for Hennegan than representing the halftone dot structure, Fleury says. That's primarily because of the accuracy and day-to-day reliability the company strives to achieve in its processes, but its use of stochastic screening is also a factor, he explains. "Our printing has a near-photographic look and you don't see a rosette pattern any more."

In part because it isn't "hung up on dots," Fleury expects the company to move to some sort of ink-jet device for color proofing in the future. "As long as the color fidelity and image quality is there, price will start dictating that we look at other options. We are going to need a plotter that offers a 175- to 200-line screen before we would jump, and the machines will get there in the next couple years," he predicts.

"I can also see there being a time when a low-cost proofer provided by us or the client and connected via the Internet will output color-managed proofs for them to approve color locally," Fleury adds.

Color + Graphics' Bishop says he keeps hearing about ink-jet devices getting better, but he personally has yet to come across one that could meet his customers' needs.

"I see the thermal proof prices coming down, but I don't see us replacing thermal with an ink-jet solution," he explains. "The market we compete in is a little special, and high-end proofing differentiates us from shops using ink-jet systems."

Quality Graphics' Yeats also believes halftone dots will continue to be a requirement in proofing, but in one or two years he expects to start seeing ink-jet devices able to produce dots.

"These machines already have 1,440x2,880-dpi engines, while a platesetter images at 2,400 dpi. I don't see any reason why, at some point, there won't be 2,880x2,880 ink-jet engines that will reproduce dots," he says. "At that point, the cost will justify our looking at ink-jet solutions."

Dots are only part of the equation, though, the general manager points out. "We have to maintain very tight control over the calibration of our proofers. The current halftone devices are very steady compared to ink-jet machines."

Regardless of the underlying technology it uses, the ultimate test of any proofing system is whether or not it meets the client's needs, Yeats concludes.
 

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