HDPrintHDPrintand other screening typesand other screening types

Mihai Necsulescu - Zoom-Soft s.r.l. ROMANIAMihai Necsulescu - Zoom-Soft s.r.l. ROMANIA

About screening typesAbout screening types Halftone reproduction on printed paper with offset printing Halftone reproduction on printed paper with offset printing technology is done with printing plates. The process is ON/OFF, technology is done with printing plates. The process is ON/OFF, printing or not printing of ink by turning ON and OFF extremely small printing or not printing of ink by turning ON and OFF extremely small pixels according to the output resolution of CTP. These pixels are pixels according to the output resolution of CTP. These pixels are gruped together and form screens, very small areas define one gruped together and form screens, very small areas define one graylevel that will be perceived so by human eye due to interpolation graylevel that will be perceived so by human eye due to interpolation of viewing. of viewing. When these pixels are grouped together and form a geometric When these pixels are grouped together and form a geometric figure like circle, ellipse, square, rhomb or even donat the screens are figure like circle, ellipse, square, rhomb or even donat the screens are called classical. These small geometric figures are never seen by called classical. These small geometric figures are never seen by naked eye but stand at the base of any color printed image. naked eye but stand at the base of any color printed image. When pixels are not making geometric figures the screens are When pixels are not making geometric figures the screens are called stochastic, but here are different flavors according to different called stochastic, but here are different flavors according to different manufacturers. manufacturers. Is also possible a mix of these technologies of screening. Is also possible a mix of these technologies of screening.

• AM screening when the shape is modulated in amplitude or the AM screening when the shape is modulated in amplitude or the mathematical curve describing the raster dot is smaller or larger for mathematical curve describing the raster dot is smaller or larger for describing different shades of gray (or color)describing different shades of gray (or color)

Important characteristic is the shape, number of cells per inch or Important characteristic is the shape, number of cells per inch or centimeter and the angle of the shape.centimeter and the angle of the shape.

• FM screening, where the pixels are making different patterns that FM screening, where the pixels are making different patterns that look arbitrary, random or stochastic.look arbitrary, random or stochastic.

Examples:Examples:

• Eliptical dot, good results at slurring and images do not have tonal jumps near Eliptical dot, good results at slurring and images do not have tonal jumps near 50% gray because the dot is not simetrical so the dot are touching only in one 50% gray because the dot is not simetrical so the dot are touching only in one axis first and then in the other axis.axis first and then in the other axis.

• Euclidian dotEuclidian dot

• Round dotRound dot

• Rhomboidal dotRhomboidal dot

• Square dot type 1Square dot type 1

Square dot type 2Square dot type 2

• micro-screeningmicro-screening

• FM screening – frequency modulatedFM screening – frequency modulated

FM screening is totally different from AM screening:FM screening is totally different from AM screening:

FM do not have angles, do not make moire, do not interfere with image FM do not have angles, do not make moire, do not interfere with image elements, have a better reproduction od iamge details, are less elements, have a better reproduction od iamge details, are less sensitive to register errors, images are clearer and most notable offer sensitive to register errors, images are clearer and most notable offer an ink reduction between 3 and 15% compared with AM screening of an ink reduction between 3 and 15% compared with AM screening of 150 – 175 lpi.150 – 175 lpi.

BUT flat tints suffer from “noise” are more difficult to print and controll on BUT flat tints suffer from “noise” are more difficult to print and controll on press, shadows are quickly plunged, and generally calibration and press, shadows are quickly plunged, and generally calibration and linearisation is a little messy.linearisation is a little messy.

• MediumMedium• CoarseCoarse • FineFine • Super FineSuper Fine

HDS or Harlequin Dispersed Screening is a registered mark of Global Graphics, HDS or Harlequin Dispersed Screening is a registered mark of Global Graphics, Staccato is a registered mark of Creo / Kodak, Randot X is registered mark by Staccato is a registered mark of Creo / Kodak, Randot X is registered mark by Screen and Satin is a registered mark of Heidelberg.Screen and Satin is a registered mark of Heidelberg.

They all look similar but with some notable differences They all look similar but with some notable differences

What is RESOLUTION?What is RESOLUTION?Is the capacity of an optic system to show clear and separate two adjacent parts of an Is the capacity of an optic system to show clear and separate two adjacent parts of an object or an image, pixels in our case for CTP.object or an image, pixels in our case for CTP.More pixels per inch mean more resolutionand more resolution is better but sometimes More pixels per inch mean more resolutionand more resolution is better but sometimes one single pixel will not appear on a plate or will not hold ink one single pixel will not appear on a plate or will not hold ink when print.when print.

And increasing two times the resolution mean 4 times larger output files therefore And increasing two times the resolution mean 4 times larger output files therefore more time to render, transfer and double the time to image...more time to render, transfer and double the time to image...

Equivalence between FM and AMEquivalence between FM and AMvalid for Harlequin Dispersed Screening from Global Graphics:valid for Harlequin Dispersed Screening from Global Graphics:HDS Coarse = 150 LPI for postersHDS Coarse = 150 LPI for postersHDS Medium = +200 LPI, commercial printingHDS Medium = +200 LPI, commercial printingHDS Fine = +300 LPI not recommended due to calibration anHDS Fine = +300 LPI not recommended due to calibration an linearisation problemslinearisation problemsThese findings are resolution dependent!These findings are resolution dependent!

New screenings – XMNew screenings – XMAGFA and CREO introduced the new “HYBRID” AM:AGFA and CREO introduced the new “HYBRID” AM:

in highlights and shadows the conventional AM in highlights and shadows the conventional AM screening is changing to FM screeningsscreening is changing to FM screenings

From From www.creo.comwww.creo.com

From From www.agfa.comwww.agfa.com

XM (Cross Modulation) Once XM reaches the smallest reproducible dot for a specific press, it no longer makes the dots smaller. Instead, it uses a patented method to “take-out” dots. Even though the dots at the highlights may appear to be random, you will notice the dots continue to align along defined AM angles.

““AGFA Sublima XM is like using FM AGFA Sublima XM is like using FM screening in shadows and screening in shadows and highlights regarding the highlights regarding the rendered details”rendered details”

• ““... does not generate the visible ... does not generate the visible noise as the FM screening does”noise as the FM screening does”

• ““... transition between FM and ... transition between FM and AM screening is around 8% AM screening is around 8% dot...”dot...”

• ““... is much easier for the ... is much easier for the printing crew to work with a printing crew to work with a screening where the smalest dot screening where the smalest dot is not going under 21 is not going under 21 microns...”microns...”

Benefits of the new screening metods of Hibrid or XM according to Benefits of the new screening metods of Hibrid or XM according to Agfa and Creo: Agfa and Creo:

DM (Digital Modulated) screening or Auraia DM (Digital Modulated) screening or Auraia from Hamiltonroad Ltd. UKfrom Hamiltonroad Ltd. UK

• Invented 6 years ago by Andi Cave, one of the founders of Invented 6 years ago by Andi Cave, one of the founders of Harlequin RIP core, now free-lancerHarlequin RIP core, now free-lancer

• The most advanced screening method existing today, is a The most advanced screening method existing today, is a combination between all screening technologies, being most of the combination between all screening technologies, being most of the time FM with AM accentstime FM with AM accents

• Started as a screening method for violet platesetters where the Started as a screening method for violet platesetters where the output results are not as good as thermal or UV platesetters now output results are not as good as thermal or UV platesetters now this screening technique is available for all platesetters.this screening technique is available for all platesetters.

• Because it use small dots it show an ink consumption reduction Because it use small dots it show an ink consumption reduction between 15 and 30%, depending od image contentbetween 15 and 30%, depending od image content

• Is similar in output results to HDPrint but in medium tones is noisier Is similar in output results to HDPrint but in medium tones is noisier as you may see in next slides comparation:as you may see in next slides comparation:

AURAIA or DMAURAIA or DM AURAIA or DMAURAIA or DM HDPrintHDPrintHDPrintHDPrint

Medium tonesMedium tones

AURAIA or DMAURAIA or DM AURAIA or DMAURAIA or DM HDPrintHDPrintHDPrintHDPrint

ShadowsShadows

ENLARGEDENLARGEDOn plateOn plate

HDPrintHDPrintHDPrintHDPrint

HDPrintHDPrintHDPrintHDPrint

• Zoom-Soft developed a special control Zoom-Soft developed a special control stripe that should appear on each plate stripe that should appear on each plate for monitoring the exposure – for monitoring the exposure – developping process to guarantee perfect developping process to guarantee perfect processed plates each timeprocessed plates each time

Control stripe is very sensitive to minor Control stripe is very sensitive to minor variation of the process without any variation of the process without any measuring devicemeasuring device

Quality controll of each and every plateQuality controll of each and every plate

- reading is done in a blink of an eye by the operator without any - reading is done in a blink of an eye by the operator without any devicedevice- operator adjust the process of developping the plate accordingly to - operator adjust the process of developping the plate accordingly to maintain integrity of all small dots, including the smallest 16 micronsmaintain integrity of all small dots, including the smallest 16 microns- HDPrint is possible only in a tight controlled environment showing - HDPrint is possible only in a tight controlled environment showing that we can reproduce on plate and print not only 1 – 99% at 200 lpi that we can reproduce on plate and print not only 1 – 99% at 200 lpi but 0.01% and 99.99% at an equivalent of 450 lpi but 0.01% and 99.99% at an equivalent of 450 lpi

HDPrint can reproduce on conventional UV plates whole range HDPrint can reproduce on conventional UV plates whole range between 0.01% and 99.99% at 450 lpi exceeding by far any plate between 0.01% and 99.99% at 450 lpi exceeding by far any plate manufacturers technical specificationsmanufacturers technical specifications

HDPrint don't make miracles: HDPrint don't make miracles: bad plates = NO HDPrint possiblebad plates = NO HDPrint possible

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