Paul Gestels has worked across multiple imaging science disciplines in both analog and digital research fields. With more than 30 years of professional experience, Paul has left his mark on the product range of Agfa’s Offset division, including ColorTune, Agfa’s color management solution.

Paul is one of Agfa’s senior image quality experts with a strong focus on color management, screening, and proofing applications. His knowledge of printing techniques and color processing algorithms contributed significantly to the smooth go-to-market of the SPIR@L screening product.

SPIR@L Screening: Agfa’s New Breakthrough Technology Defining a New Reference

Rudi Bartels, Els Van Cauwenberghe, Paul Gestels, and Christophe Cleeren, Agfa

In 2020, Agfa introduced SPIR@L screening, an innovative technology with major advantages over conventional and other more modern screening technologies. Just like Agfa’s Sublima™, SPIR@L screening is an XM screen that allows for highlights and shadows to be reproduced to their full extent but with the additional benefit that substantially less ink is required to achieve the same reproduction.

As in conventional screening, darker tones are created by enlarging small highlight dots into larger AM dots. However, contrary to the conventional ways, the small highlight dots are now enlarged in the form of a spiral instead of a solid round dot. The spiral curve has a certain thickness, which we call the ‘curve’. The pitch defines the empty space between two windings, which is called ‘groove’. In order to produce the best output for a particular combination of printing process, ink and paper, it is possible to adjust the curve and groove dimensions, giving this technology a very large latitude. The relation between these two parameters is key to press stability.

By making the AM dot grow as a spiral, fine details in the mid tones are rendered with more contrast. The lattice of the screen is less visible, in fact allowing to achieve similar or higher image quality, while printing at lower screen rulings – increasing latitude for printers.

Last but not least, by using this technology, less ink is needed in order to get the same density, as the ink is spread more efficiently. Consequently, a significant amount of ink is saved – on average 10%, evaluated in hundreds of cases and on top of already installed ink save techniques like e.g. GCR.

This paper contains a technical description of how the screen is built as well as some figures of the tests we have done. Currently, SPIR@L has been installed and shown to be operational for commercial heatset, coldset newspaper, offset packaging and commercial sheetfed. More than 100 splitruns (comparing SPIR@L to other screening technologies, by printing half of the job with SPIR@L screening and half of the job with the incumbent screening) – have been performed and have proven that SPIR@L does indeed account for significant ink-saving, while keeping image quality and color gamut/density.

In print, both conventional AM screening and FM screening are used. In most cases FM screens give sharper images but are seen as more noisy, have a slightly lower ink consumption yet are much more difficult and instable to print. AM screening on the other hand is less noisy and much stabler in print. Agfa’s new SPIR@L screening combines the advantages of both. Flat tints are rendered less noisy than with FM, ink consumption is considerably lower than with conventional AM and FM screening and the good print stability of conventional screening is maintained.

In this paper Agfa’s SPIR@L screening is explained.