I promise you, this is not about platesetters or plates. The solutions I have uncovered won’t cost anywhere near as much, yet they will go a long way in helping you to produce a better-looking newspaper. This is one of the many benefits of computer-to-plate. It enables the application of so many other quality-improvement technologies.

Halftone proofing

We are all too familiar with those nasty little aberrations, known as moiré, which can happen from prepress en route to press. Because moiré patterns are the result of halftone screen interferences, the only way you can spot them before going on press is by producing a halftone proof.

In a high-productivity digital workflow, most prepress departments use inkjet systems, which produce composite proofs. Well, the technology has advanced even further. Now you can produce halftone proofs using an inkjet proofer. There are other benefits from halftone proofing, such as being able to check the accuracy of image trapping.

If your proofing software is not capable of outputting halftones, there is another alternative — an output manager that provides a monitor preview (softproof) of the rasterized files before going to plate.

Screening technologies

Of course there is another way to avoid the moiré problem: Eliminate the screen that causes it. Then you won’t have to worry about halftone proofing at all. And that will save you time as well as grief.

Stochastic screening is certainly not new but has typically not been used for newspaper production. That’s because along with its photo-like reproduction comes a few caveats. Luckily, your commercial counterparts have ironed out most of the kinks.

The difference between conventional screening and stochastic is the formation and placement of the dots. Halftone screens create an arrangement of equally spaced dots, which change in size proportionally to the tone value of the original. The higher the density, the larger the dot, but it always stays in position. This is known as amplitude modulation, or AM. Because each dot is immovable, each of the four color screens have to be angled slightly, hence forming the rosette pattern. If the original image has a screen-like pattern, such as a checkered shirt or a brick wall, it introduces another “screen,” which causes the moiré.

FM usage

Stochastic screening uses frequency modulation, or FM. Here equally-sized microdots are variably spaced and increase in number or frequency depending on the density or tonal value of the image.

The beauty of stochastic screening is that it produces photographic quality because there are no real screens. So not only does it eliminate moiré patterns, it dramatically increases quality.

Without stringent quality control, stochastic screening can be something of a headache on press. When it was first introduced, there was no CTP. The problem in a film workflow occurred in image areas below 5 percent density. It was difficult to hold the microdot from film to plate. Computer-to-plate completely eliminated this problem. However, users tell me that unless you maintain strict standards, problems can still occur on press.

But because technology never stands still, there is a new screening technology that is perfect for high-speed production. It is a hybrid of AM and FM screening. In commercial applications today it produces screen resolutions equivalent to conventional screen rulings from 210 to 340 lines per inch, yet it RIPs at only 2,400 dots per inch to achieve the highest resolution.

The software applies AM screening to midtones and FM to low- and high-density areas. But it isn’t that simple. It very carefully transitions from one to another creating a new species of modulation.

What makes it better than FM alone is that it actually makes prepress easier and requires no extra work on press.

Steve Ainsworth, print manager for Newsquest Southern in the United Kingdom, a subsidiary of Gannett, uses this technology.

“With the new screening we print at 180 lpi coldset and have a much improved dot structure and a superior, ‘cleaner’ image … the benefits are overall improvement in quality. And it couldn’t be easier,” He said. “Another bonus is that we also have the ability to print products heatset through one print tower in tab/broadsheet and A4 production on coated stocks. This allows us to print all our heatset production at 180 lpi at 1,270 dpi resolution.”

If this doesn’t motivate you to switch to CTP, I give up.

Rosemarie Monaco is the chief executive officer of Group M Inc., a marketing communications and consulting firm specializing in the graphic arts. Send comments and questions to rmonaco@groupm.org.