Dainippon Screen’s SPEKTA is an innovativehybrid screening method which eliminatesmoiré and broken lines and delivers printquality and detail comparable to 300+ linehigh-frequency screening without having tomake any changes to conventional printmanagement facilities.SPEKTA is a way to achieve high-end printquality using standard level equipment.When you see the difference in quality it canprovide on the printed sheet, you will seethe competitive power it will add to yourbusiness. It is simply a better way to work.

A revolution in screening technology

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The digital revolution has brought a sea change to the prepress world, butthe nature of the final printed product has hardly changed at all. Mostcolor print matter with strong visual elements, such as brochures,

pamphlets and magazines, is still printed using the same conven-tional 175 lpi Amplitude Modulation (AM) screening methodsthat were used before the digital revolution.

Conventional AM screening reproduces light and darkness by vary-ing the size of halftone dots. It is currently the screening method thatis used most in printing because the pitch and angle of the dots arefixed, and the method achieves consistent tonal reproduction.

Nevertheless, AM screening has drawbacks. Because the halftone dotsare evenly spaced and at angles, AM screening is prone to moiré result-ing from factors such as plate misalignment and interference patternsbetween screen angles and images. Other typical problems includejaggedness and segmenting of fine lines and tone jumping in gradationareas. These kinds of problems are particularly troublesome because theyare generally not detectable prior to printing. These problems are also hin-dering the transition to fully digital workflow, including the adoption ofcomputer-to-plate (CTP) and the streamlining of the color proofing process.Efficiency-boosting measures such as eliminating direct digital color proof-ing, or using a color printer for proofing, remain dangerous because of therisk of overlooking problems such as moiré.

Trying to achieve higher print quality by using higher frequency AM screenrulings also has drawbacks. Printing with high-frequency screening requiresstricter print management conditions. That is why only a small minority ofprinters use high-frequency screens of 300 lpi or higher.

Despite the spread of powerful graphics software that makes it simple to generatehigh-resolution data, the most common screening method in use, 175 lpi AMscreening, leaves the graphic arts industry largely unable to get the most out ofsuch detailed graphics and images.

Frequency Modulation (FM) screening spent some time in the limelight as analternative to conventional AM screening. FM screening places microdots ofequal size randomly, and varies their density to reproduce lightness and darkness.Not only does this approach eliminate the moiré and broken lines associated withAM screening, it also supports higher resolution printing.

Unfortunately, FM screening demands a rigorous print production environment,which means higher printing costs. Also, compared to AM screening, it is moredifficult to print midtones and shadow areas consistently, and the midtones andhighlights tend to appear grainy. Despite its other advantages over AM screening,FM screening's own drawbacks have kept it from being more widely implemented.

AM dots

ixed reviews for both AM and FM screening

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Now Dainippon Screen has, for the first time, taken the best from AMscreening, the most commonly used screening method today, and FMscreening, and melded them together in an innovative hybrid screening

product, SPEKTA, that overcomes the weaknesses and delivers the key strengthsof both methods.

SPEKTA uses AM-like dots or FM-like dots depending on the color density ofgiven areas. By doing so, it achieves the following remarkable characteristics:

1. With the standard 2,400 dpi resolution that is typically used to output 175lpi AM screens, SPEKTA achieves a level of detail comparable to high-fre-quency line screens of 300 lpi or higher. Moreover, it leaves no jagged or broken lines.

2. It does not generate moiré because it creates no screen angles.

3. It can be printed under standard printing conditions and operator skill levels.

In the 1–10% highlights and the 90–99% shadows, SPEKTA uses FM screen-ing's fixed dot size and reproduces tone by varying the density of these uniformdots. In the 10–90% midtones, it varies the size of the round dots just as AMscreening does.

However, the placement of all of these dots is random as in FM screening, whichmeans there are no screen angles to contend with. As a result, SPEKTA avoids themoiré resulting from factors such as plate misalignment and interference patternsthat plague conventional AM screening. SPEKTA overcomes the difficulty ofprinting FM screens by setting the size of the smallest dot slightly larger than inFM screens. It also minimizes tone jumping through advanced methods devel-oped for positioning and joining dots.

he best of AM and FM screening

SPEKTA

SPEKTA dots

AM dots SPEKTA dots

SPEKTA eliminates the rosette moiré on the hairline and neck.

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Let's take a look at some samplesthat illustrate SPEKTA's effective-ness. Starting from exactly the

same data, one sample in each pair hasbeen output using conventional 175 lpiAM screening, while the other has beenoutput using SPEKTA. The press andprint conditions were identical. The dif-ferences are unmistakable.

Eliminates moiré

It is difficult to avoid moiré from interfer-ence between screens and image patternssuch as lace. In this case, while AM screen-ing does generates moiré, SPEKTA doesnot. SPEKTA is also able to reproduce col-ors that the moiré from conventional AMscreening interferes with, making its colorsaturation closer to that of the original.SPEKTA also not only eliminates the moiréfrom the CRT screenshot in Sample 2, butalso shows its superior capabilities for repro-ducing the text in such images.

Brings out color in the midtones

SPEKTA does a better job of bringing outthe color of the woman's dress and skin inSample 1. Compared to conventionalscreening, the blue of the dress is fresherand the skin color appears more vibrant.SPEKTA beats AM screening in reproduc-ing images with rich colors, such as pho-tographs of flowers and fruit.

Reproduces lines and details crisply

In Sample 3, SPEKTA demonstrates itssuperior reproduction of fine details such asthose shown in the maps. Compared to thelower map, SPEKTA provides a muchclearer reproduction of the fine lines created with halftones and of the tints usedto indicate different areas.

uality comparable to 300+ lpi, but under

standard printing conditions

SPEKTA

SPEKTA

Sample 1

Sample 2

Sample 3

AM screening

AM screening

SPEKTA

AM screeningAM screening

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Because 175 lpi AM screening tends to leavelight-colored fine lines jagged and broken,printers must often resort to using spot colorsto reproduce them. However, SPEKTA canreproduce these kinds of images sharply usingonly process colors.

The woman's hair and the wood grain of thefurniture in Sample 4, as well as the finedetail in the copper plate print and the texton the liquor label in Sample 5, show howSPEKTA clearly reproduces image areas thatconventional screening loses.

SPEKTA beautifully reproduces details in otherimages that conventional screening typicallyleaves buried, such as the mesh in stereo speak-ers and the detailed patterns in fashion fabrics.

Eliminates rosette moiré

As can be seen in all these samples, SPEKTAeliminates the rosette moiré typical of imagessuch as product shots with a lot of black inthem and photographs with light backgroundareas. SPEKTA brings out the life of the origi-nal image and enables a natural and immediatesense of realism on the printed sheet.

Smoothly reproduces images that

FM screening can make grainy

Although FM screening tends to generatetone jumping in images with gradations, suchas photographs of the sky, SPEKTA repro-duces such gradations naturally and beautiful-ly. And while FM screening would tend toleave certain images grainy, such as a whiteporcelain teapot and cup, SPEKTA makesthem appear smooth and realistic. SPEKTAconsistently renders smooth gradations inshadow areas as well.

While printing high-frequency AM screensplaces more rigorous requirements on print-ing conditions and technique, SPEKTA pro-duces superb print quality that is comparableto 300+ lpi AM screening, but on standardprinting equipment and with standard printresolution data. Work that previously requireda strict print management system, greateroperator skill, or the use of spot colors forcertain fine lines, can now be done withSPEKTA at a greatly reduced cost.

AM screening AM screening

AM screeningSPEKTA

SPEKTA

Sample 4

Sample 5

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Tom Pettey knew he had a winner when he first saw Spekta at theGraph Expo 2000 show in Chicago last September. Pettey and his sonshave made a habit of being first. Glenbard Graphics was the first com-pany in the Midwest to install a PlateRite 8000 thermal CTP platerecorder shortly after Graph Expo 98. Now they are the first to employSpekta, the groundbreaking hybrid halftone screening technology thatproduces the high-end quality and detail usually associated with screenrulings of 300 lpi or more, but achieves this at 150 lpi. Spekta deliversthis superb quality by intelligently blending the well known advantagesof FM screening with conventional AM screening for output onto posi-tive plates from the PlateRite 4000 and 8000 series.

"When we were the firstMidwestern printer to installthe PlateRite 8000, Screenpromised it would produceoutstanding quality and ithas," said Pettey. "Qualitywas an issue with Spekta,but it too has lived up to itsadvanced billing. The detailis truly amazing and ourcustomers are extremelypleased at receiving betterlooking reproductions onthe printed sheet."

Spekta also overcomes both the rosette moiré and object moiré patternsthat have been well known up to now as problems difficult to avoid,even when using digital image processing. It improves the reproductionof fine lines in maps and other detailed diagrams, and enables images ofTV screens, fine wood grain, stereo speakers, clothing with sharp pat-terns and other traditionally difficult areas, to be reproduced with anart-book clearness that has never been more accessible. With qualitycomparable to 300+ lpi printing, it is invaluable to Glenbard Graphics,which is using Spekta for all of the work done on its web press.

"We use our web press two shifts a day, seven days a week, and do avariety of work up to six colors on coated sheets," explained Pettey. "Inthe past, in order for us to get 200 line screens per inch, we had to runat 4,000 dpi. Spekta now gives us high resolution, sharp dot reproduc-tion and superb registration at 2,400 dpi, and we are getting these ben-efits faster than before. We like the PlateRite 8000 for its speed andability to cut time in producing plates. Spekta has given us the addedbenefit of cutting our platemaking time in half, so we are ready to gowith our plates in just five minutes."

SPEKTA benefits everyone in the print production process,from clients and graphic designers, to prepress and print-ing professionals. Clients get a beautifully printed product.

Designers not only can achieve a better final product with thesame data, but are also released from concerns about moiré andbroken lines so they can be completely finished with jobs soon-er. With only a tiny investment, printing companies can raisethe quality of their work while continuing to use their existingstandard printing equipment.

One manager at a printing plant that already uses SPEKTA said,"One of our clients, an electronics maker, was very impressedwhen they saw the detail of the speaker mesh printed. BeforeSPEKTA, we always had to smooth out areas like that usingimage processing software because we couldn't print it withoutmoiré."

SPEKTA, which delivers all of these benefits and features, cannow be used with Screen's TaigaSPACE and Trueflow workflowRIPs and HQ-510 series RIPs, and output on Screen's PlateRite4000/8000 thermal platesetters. The sharp dot reproductionthat thermal CTP achieves makes SPEKTA hybrid screeningpossible for the first time.

Since it does not generate moiré, SPEKTA greatly boosts thereliability of color printer and online proofing. This supportsthe transition to a digital workflow and reduces costs.The arrival of SPEKTA, a revolution in screening technology,with all of these clear benefits, will surely accelerate the transi-tion to CTP, the trend of the digital era.

enefits for the entire production chain

Chicago printer gets head start with Spekta Glenbard Graphics - Illinois, USA David and John Pettey, Vice Presidents

of Glenbard Graphics

Glenbard GraphicsTom Pettey400 Fullerton Ave. Carol Stream, IL 60188Phone / 630 653 4550 Fax / 630 653-0876www.glenbardgraphics.com