Four-color printing is standard today in newspaper production, with the result that every production manager is interested in boosting quality while minimizing consumption of pricey printing inks.

To that end, German publisher Mannheimer Morgen last year began testing software it contends is helping it maintain quality and reduce costs.

The software hinges on combining  FM screening and gray component replacement, or GCR. While both technologies are well known in the printing industry, the app, DuoScreen Pro, exploits the advantages of each process, according to Harald Blendowski, the newspaper’s technical manager.

Harald Blendowski, technical manager at Germany’s Mannheimer Morgen, with Georg Futterer, director of software vendor MMS.

“I was initially skeptical,” he said. “The fact that the FM screening in this case only affected the images caught my attention, so I wanted to try it and see.”

Exploits benefits

DuoScreen, developed by Heidelberg, Germany-based MMS, capitalizes on the irregular dot distribution of FM screening to eliminate disturbing rosette patterns but otherwise allows the retention of customary AM halftone screens where desired.

In the first step, the software processes the image data extracted from the PostScript file produced by the paper’s alfa editorial system. DuoScreen also optimizes the image using GCR and applies the FM screen. The screened data is transmitted together with the remaining page data to the RIP of the plate imager.

The RIP recognizes the FM-screened image areas and exposes them directly onto the plate while all the other information not processed by DuoScreen is transmitted as an AM screen to the plate.

The FM resolution depends on the imager resolution as well as on how many imager dots are combined to one halftone dot: in Mannheim, the resolution of the imager is 1,270 dots per inch and four imager dots are combined to one halftone dot in each case (resulting in a resolution in the image area of 635 dpi).

Comparing AM and FM screens provides visible proof, Blendowski said. “The FM screen enhances the sharpness of the images and register differences are no longer so evident,” he said.

Blendowski said the Agfa computer-to-plate imagers play a key role. The violet systems produce sharper, more stable dots, he said.

Recalculates data

At the same time, ink consumption also dropped, fueled in part by the addition of GCR as the RIP data is recalculated to support FM conversion.

The replacement is managed by so-called DeviceLink profiles (produced with Color Solutions Devil software) that are used to replace the gray element of the color inks with black.

The software essentially converts the input, or reference, profile to a color-optimized output profile without requiring a neutral L*a*b color space.

Since Mannheim Morgen began evaluating DuoScreen, color ink consumption dropped by 18 percent, a result that requires additional study in order to better understand how the software works, said Manfred Werfel, Ifra’s deputy chief executive officer and research director.

One theory: “In the conventional AM screen, the half-tone dots are characterized by a regular arrangement but a different size,” he said. “With the FM screen, all dots are the same size, but arranged irregularly. To achieve the same coverage, the AM screen needs fewer, but bigger dots. The bigger a dot is, the greater the surface tension of the ink drop and therefore the bigger the amount of ink that is picked up by the half-tone dot on the plate and transferred to the paper.” 
 

This article has been edited for length and to conform to Newspapers & Technology’s style. The original article was first published in IFRA magazine, Ifra’s monthly publication. If you have any comments or questions bout this article, please send them to ntreader@ifra.com.