Harlequin® Screening Library

Global Graphics’ in-RIP screening technologies are known collectively as the Harlequin Screening Library™ (HSL). HSL give OEMs the widest possible choice for their applications and printing targets. A wide range of powerful and tunable halftone technology can be supplied, including multi-level screens for inkjet presses with the benefit that screening occurs automatically within the RIP. Alternatively and OEM may also install their own screening as encrypted font caches or using and API for programmatic halftone technology.

The Harlequin Screening Library includes:

Harlequin Precision Screening™ (HPS)

HPS is an enhancement to conventional screening that uses a proprietary algorithm to calculate the screen angles and frequencies for a particular image that most effectively reduces moiré while minimizing memory requirements.

HPS can make minor adjustments to the selected angles and frequency within a specified range to achieve extremely high quality results. The resulting efficiencies in memory usage and decrease in processing times are dramatic. HPS also provides the ability to generate extra gray levels on demand, other than the ones predicted in a given job.

Harlequin Chain Screening™ (HCS)

Harlequin Chain Screening uses an elongated dot shape to create better reproductions of certain images such as computer-generated graphics. Instead of the conventional symmetrical dot shape, HCS uses a long elliptical dot to produce a chain-like structure.

The elliptical dot creates particularly smooth flat tints and vignettes even when working at relatively low screen rulings. This makes HCS particularly well-suited to printing charts, weather maps, and other computer-generated graphics and also for printing processes such as those used for news print.

Harlequin Dispersed Screening™ (HDS)

HDS is a patented second- generation stochastic screening algorithm that eliminates many of the problems with other stochastic techniques as well as providing a high-quality alternative to conventional screening.

Harlequin Error Diffusion Screening™

EDS is a frequency modulated (FM) screening method that can be used to avoid image artifacts in color proofs. EDS screening is particularly good at low resolutions because it does not use dot patterns and therefore produces prints that are free from moiré.

EDS screening typically produces smoother vignettes than amplitude modulated (AM) screening and is good at reproducing fine detail. It is for these reasons that EDS screening is particularly suited to the production of proofs on inkjet printers.

Harlequin Cross Modulated Screening (HXM)

Harlequin Cross Modulated Screening merges the best aspects of stochastic and conventional screens: giving smooth, noise-free flat tints while retaining fine detail in highlights and shadows. It produces pin-sharp images and dramatic color.

Harlequin Dispersed Screening is Global Graphics’ patented second-generation stochastic screening system and is the standard screening method included in versions of the Harlequin RIP designed for low-resolution output devices.

HDS creates reproductions with increased sharpness over conventional screening methods and offers complete freedom from both cross screen and object moirés. HDS addresses many of the deficiencies in other stochastic screening techniques to provide a robust and high-quality screening solution for a variety of printing situations.

Features

Unique Screen Structure: HDS is ideal for reproducing subjects for which moiré is a problem and where detailed reproduction is required. HDS offers increased image sharpness and fewer press registration problems over conventional screens and addresses those problems that other FM screening methods have been unable to overcome.

Incredible Speed and Performance

when combined with the power of the Harlequin RIP HDS can be implemented with no speed penalty and with speed and performance gains over other FM screening methods. With the ability to produce high-quality output at incredible speeds, HDS leads the industry in performance.

Smart FM Dot Dispersal Means Higher Quality Images

HDS eliminates the grainy highlight effect experienced with some FM screening methods. These artefacts are most apparent in smooth areas of contone pictures, flat tints, and vignettes and are the result of purely random screening methods that cluster dots into odd sized and shaped structures.

The HDS approach dramatically improves the printability, stability, quality and predictability of the printing process.

FM Screening for Everyone

Global Graphics is focused on providing best of breed technology to its partners. HDS is not limited to a certain device from a certain manufacturer, or even to a specific software application from one vendor. Our OEM partners have implemented HDS successfully on all sorts of imaging devices, from image setters to ink-jets.

The HDS Family

HDS provides a family of screens, tailored for different types of reproduction and different output device capabilities. HDS includes standard four colorant screens for use with the standard CMYK process colors as well as variants developed for hexachrome and photoink devices.

HDS is also available in five varieties of dot structures or “settings” - from Super Fine to Super Coarse - making it compatible with many different types of output device.

Harlequin Cross Modulated Screening merges the best aspects of stochastic and conventional screens: giving smooth, noise-free flat tints while retaining fine detail in highlights and shadows. It produces pin-sharp images and color that leaps from the page and helps overcome common printing imperfections like rosettes and moiré.

HXM allows you to print screens at a higher line ruling than would normally be considered reliable.

In conventional screening technologies, the size of the smallest printable dot possible on paper will control the level of detail that can be reproduced by a given system.

Higher screen rulings produce very small structures in the highlight and shadow areas and these are inclined to be lost, so this has the effect of limiting the range of tonal reproduction.

The higher the screen ruling, the further the tonal range is compressed for a given system. The intention with HXM is to limit the smallest structure produced to be that which can reliably be printed on the target system. Once this point is reached, within a given HXM screen, structures are removed completely rather than continuing to be reduced in size to create the required tonal range.

In the case of shadow printing at higher screen rulings with conventional screening often causes the dots to merge completely causing tones in the 95 - 100% range to all print as solid resulting in a loss of shadow detail because all of these tints end up printing the same. HXM has the unique ability to control the size of the spot in the shadow or dark end of the tone scale (along with the highlight end of the tone scale) thus insuring the full tonal range is printable even at the higher screen rulings HXM is optimized for.

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