staccato 2.0 user guide - resources.kodak.com · staccato.book page iii tuesday, june 26, 2001...

03-4049E-A

StaccatoVersion 2.0

User GuideEnglish

staccato.book Page ii Tuesday, June 26, 2001 10:37 AM

staccato.book Page iii Tuesday, June 26, 2001 10:37 AM

CopyrightCopyright © 2001 Creo Products Inc. All rights reserved.

CreoScitex is a major operating division of Creo Products Inc.

No copying, distribution, publication, modification, or incorporation of this document, in whole or part, is permitted without the express written permission of CreoScitex. In the event of any permitted copying, distribution, publication, modification, or incorporation of this document, no changes in or deletion of author attribution, trademark legend, or copyright notice shall be made.

The text and drawings herein are for illustration and reference only. The specifications on which they are based are subject to change. Creo Products Inc. may, at any time and without notice, make changes to this document. Creo Products Inc., for itself and on behalf of its subsidiaries, assumes no liability for technical or editorial errors or omissions made herein, and shall not be liable for incidental, consequential, indirect, or special damages, including, without limitation, loss of use, loss or alteration of data, delays, or lost profits or savings arising from the use of this document.

No part of this document may be reproduced, stored in a retrieval system, published, used for commercial exploitation, or transmitted, in any form by any means, electronic, mechanical, photocopying, recording, or otherwise, without the express written permission of Creo Products Inc.

This document is also distributed in Adobe Systems Incorporated's PDF (Portable Document Format). You may reproduce the document from the PDF file for internal use. Copies produced from the PDF file must be reproduced in whole. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TrademarksThe CreoScitex script, the CreoScitex swooshes logo, and the names of the CreoScitex products and services referred to in this document are trademarks of Creo Products Inc.

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FCC ComplianceThe CreoScitex equipment referred to in this document complies with the requirements in Part 15 of FCC Rules for a Class A computing device. Operation of the CreoScitex equipment in a residential area may cause unacceptable interference to radio and TV reception, requiring the operator to take whatever steps are necessary to correct the interference.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Limitation of LiabilityThe product, software or services are being provided on an “as is” and “as available” basis. Except as may be stated specifically in your contract, Creo Products Inc. and CreoScitex (jointly referred to as “Creo”) expressly disclaim all warranties of any kind, whether express or implied, including, but not limited to, any implied warranties of merchantability, fitness for a particular purpose and non-infringement.

You understand and agree that Creo Products Inc. or CreoScitex (jointly referred to as “Creo”) shall not be liable for any direct, indirect, incidental, special, consequential or exemplary damages, including but not limited to, damages for loss of profits, goodwill, use, data or other intangible losses (even if Creo has been advised of the possibility of such damages), resulting from: (i) the use or the inability to use the product or software; (ii) the cost of procurement of substitute goods and services resulting from any products, goods, data, software, information or services purchased; (iii) unauthorized access to or alteration of your products, software or data; (iv) statements or conduct of any third party; (v) any other matter relating to the product, software, or services... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

PatentsThis product is covered by one or more of the following U.S. patents:

.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Creo Products Inc.3700 Gilmore WayBurnaby, B.C., Canada V5G 4M1Tel: (1) (604) 451-2700Fax: (1) (604) 437-9891

http://www.creo.com.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

03-4049E-A

Revised June 2001

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http://www.creo.com

Contents

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Using This Manual viiWho Should Use This Manual ................................................................................................................. viiiConventions Used in This Manual ........................................................................................................... viii

Fonts ............................................................................................................................................... viiiTerminology ...................................................................................................................................... ixSymbols..............................................................................................................................................x

PDF Document ..........................................................................................................................................x

1 Screening Basics 1Halftone and Stochastic Screening Concepts ............................................................................................ 2Halftone Screening ................................................................................................................................... 2

Dots, Halftone Cells, and Screens....................................................................................................... 3Dot Shape ......................................................................................................................................... 4Tone Value Increase ........................................................................................................................... 4

Halftone Parameters ................................................................................................................................. 5Selecting Dot Shapes ......................................................................................................................... 5Selecting Screen Ruling...................................................................................................................... 6Selecting Screen Angles ..................................................................................................................... 7

Stochastic Screening................................................................................................................................. 8Halftone Versus Stochastic Screening................................................................................................. 8

Benefits of Stochastic Screening ............................................................................................................. 10First- and Second-Order FM Screening .................................................................................................... 12Combining Screens................................................................................................................................. 14

2 Staccato Overview 15What Is Staccato? ................................................................................................................................... 16

Optimized Screening........................................................................................................................ 16Consistent Printing Conditions......................................................................................................... 16Maximum Control ........................................................................................................................... 17Output Versatility............................................................................................................................. 17

How Staccato Works .............................................................................................................................. 18Staccato Requirements ........................................................................................................................... 18

3 Getting Started 19Installing Staccato................................................................................................................................... 20Licensing Staccato on Allegro Workstation 2.0 ....................................................................................... 21

Platesetter Console .......................................................................................................................... 21Trendsetter Console......................................................................................................................... 23

Installing Staccato on Allegro or Platesetter Workstation......................................................................... 24Write Down the License Key ............................................................................................................ 32

vi Staccato User Guide

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Generating a PPD File ............................................................................................................................. 32

4 Staccato Screens 33Selecting Staccato Screens...................................................................................................................... 34Staccato Screen Characteristics............................................................................................................... 34First-Order Screens ................................................................................................................................. 36

Staccato 20.1 .................................................................................................................................. 36Second-Order Screens ............................................................................................................................ 37

Staccato 20 ..................................................................................................................................... 37Staccato 25 ..................................................................................................................................... 37Staccato 35 ..................................................................................................................................... 38Staccato 50 ..................................................................................................................................... 39Staccato 70 ..................................................................................................................................... 40

Dot Gain ................................................................................................................................................ 41Tonal Calibration ............................................................................................................................. 41

Applying Staccato Screens ...................................................................................................................... 42

Glossary 43

Index 51

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Using This Manual

Who Should Use This Manual ...........................................................viii

Conventions Used in This Manual .....................................................viii

PDF Document....................................................................................x

viii Using This Manual

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Who Should Use This ManualThis manual is intended for operators who use Staccato screens in their prepress workflow.

This manual assumes that:

• you have a working knowledge of prepress operations

• you understand standard prepress applications, such as QuarkXPress, Adobe Photoshop, and ScenicSoft Preps

• you are familiar with using a personal computer running the Windows NT operating system

• you are familiar with using a Macintosh computer

• all the hardware, software, and network components of your system are installed, configured, and operating correctly

• files submitted to your system are free of common errors usually dealt with during preflight, such as missing fonts and PostScript errors

• preflight, such as missing fonts and PostScript errors.

Conventions Used in This ManualThis section describes the fonts, terminology, and symbols used in this manual.

FontsFrutiger bold is used to refer to buttons and other items in a dialog box, file names, folders, menu names, and menu commands.

Minion Italic is used to refer to other chapters in the manual, book titles, and titles of other manuals.

Frutiger is used for figure and table captions.

Letter Gothic is used for messages on your computer screen and for information that you must type.

SMALL CAPS is used for a key or key combination on your keyboard.

Conventions Used in This Manual ix

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Terminology

Clear Place the mouse pointer over the check box for the specified option, and click the left mouse button so that the X or check mark is removed from the check box.

Click Place the mouse pointer over the specified option or button and press and release the left mouse button.

Double-click Place the mouse pointer over the specified option or button and quickly press and release the left mouse button twice.

Drag Hold down the left mouse button while moving the mouse and release the button.

Enter Type the information and press the ENTER or RETURN key.

Point Position the mouse pointer over a submenu or menu command. For example, point to the File menu.

Press Press the specified key or key combination on your keyboard, for example, press CTRL+ALT+DEL.

Right-click Place the mouse pointer over an area of the application window, and then press and release the right mouse button to display the shortcut menu. For more information about using shortcut menus, see your Windows documentation.

Select Place the mouse pointer over the check box for the specified option, then click the left mouse button so that an X or check mark appears in the check box.

Or:

Place the mouse pointer over the specified box or button, and then click the left mouse button.

Type Type the information. Do not press the ENTER or RETURN key.

x Using This Manual

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Symbols

PDF DocumentThis manual is also provided in PDF (Portable Document Format).

The PDF document can be used for online viewing and printing using Adobe Acrobat Reader. When printing the manual, please print the entire manual, including the copyright and disclaimer statements.

Important: This tells you about things that may cause process delays or reduce functionality, reliability, or quality.

Note: A note provides additional information that you may need to consider.

1staccato.book Page 1 Tuesday, June 26, 2001 10:37 AM

Screening Basics

Halftone and Stochastic Screening Concepts .......................................2

Halftone Screening..............................................................................2

Halftone Parameters ...........................................................................5

Stochastic Screening ...........................................................................8

Benefits of Stochastic Screening ........................................................10

First- and Second-Order FM Screening...............................................12

Combining Screens ...........................................................................14

2 Chapter 1 – Screening Basics

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Halftone and Stochastic Screening ConceptsThis chapter gives you a basic understanding of the concepts related to both halftone amplitude modulation (AM) and stochastic (FM) screening.

Halftone ScreeningHalftone screening or halftoning is the process of approximating gray levels or color shades with a pattern of dots. In halftoning systems, dots can only transfer ink in an all-or-nothing fashion. In other words, it is possible only to print a uniform layer of ink or leave the paper unprinted. The overall thickness of the ink, and, therefore, the richness of color, can be varied by adjusting the ink supply. However, the ink film cannot be adjusted in discrete areas.

The reproduction of gray levels is achieved by printing small dots on paper, which our eyes integrate with the surrounding unprinted white areas. By varying the size of these dots relative to the amount of white background, you can attain a full range of integrated grays.

The percentage of ink coverage must vary to produce different shades of gray. An area of small dots appears light gray, while an area of larger dots appears dark gray. Essentially, though, it is not the size of the dots but the resulting ratio of black area to white area that represents the gray value.

Color shades are approximated with three patterns of dots, each in a primary color (cyan, magenta, and yellow). A fourth pattern of black dots is almost always used to achieve more accurate black.

Within each color separation, the size of the dots (in relation to their background) is proportional to the amount of the primary color in the composite shade. When the separations are combined, typically by overprinting in registration, they create the illusion of shades of color. The cyan, magenta, and yellow dots cannot be distinguished when viewed from a distance. Instead, the pattern of color dots appears to be an area of a color shade.

Halftone Screening 3


Dots, Halftone Cells, and ScreensDots represent the visible part of halftoning. Most halftoning can be described in terms of patterns of dots. The industry-standard terms halftone cells and screens are used to describe the organization of dots into manageable structures.

Electronically generated halftone dots are constructed within halftone cells on a grid, which is a subdivision of the resolution of the output device. Generally, the number of tonal steps is determined by the dimensions, or the number of pixels, in a halftone cell. The larger the cell, the greater the number of pixels that can be switched on and off. Therefore, a greater number of gray levels can be achieved in a halftone cell.

Figure 1 show groups of halftone cells, each with dimensions of 16 pixels by 16 pixels. With 256 spots that can be turned on or off, each dot can have 257 steps of gray between 0% and 100%. Although the number of gray levels is traditionally limited by the number of pixels in a halftone cell, the RIP adjusts the dot size in neighboring cells to create a localized average for rendering 1024 gray levels for any line frequency or any size halftone cell.

Figure 1: 50% euclidean dot (15°); 50% round dot (45°)

A screen is an invisible grid that is superimposed on an image. Each square in the grid is a halftone cell. For a particular dot shape, the important characteristics of a screen are its spatial resolution—that is the screen ruling or frequency, and screen angle.

Screen ruling or frequency is the number of halftone cells per inch or centimeter. The corresponding units are lines per inch (lpi) or lines per centimeter (lpc). For example, a screen ruling of 100 lpi means halftone cells spaced every hundredth of an inch.



Screen angle is the angle between one side of a halftone cell and an axis on the output device; it is not a fixed axis on the page. The reference axis is usually the direction of the slow scan. The screen angle becomes important when you are combining the separate patterns of dots used for color reproduction. The most important consideration is the angular separation of the different screens, not their absolute angles relative to the device axes.

Dot ShapeThe choice of the shape of each dot generated in a halftone image is essential to the quality of the final image. Figure 1 on page 3 shows round and elliptical dots, but dots can have other shapes and need not even form a connected shape within the halftone cell. For more information on dot shapes, see Selecting Dot Shapes on page 5.

Tone Value IncreaseWhen a halftone image is printed, the ink used to create each dot tends to flow outwards as it is pressed and absorbed into the paper. Furthermore, some light is diffused and trapped in the white paper spaces in between dots. The overall effects of these mechanical and optical phenomena are known as tone value increase or dot gain.

Tone value increase is a reality of printing, and it contributes to the quality of the image. Thus, on halftone output, a certain amount of dot gain is desirable. Excessive dot gain variations, however, can lead to loss of shadow or highlight detail as well as inaccurate tonal reproductions.

You can measure dot gain, and then calibrate halftone output using Harmony calibration software. Harmony lets you compensate for undesirable dot gain on your output and achieve printing with acceptable dot gain values. For more information about tonal calibration, see Dot Gain in Chapter 4.

Halftone Parameters 5


Halftone ParametersVarious screening parameters help you control your halftone output. Using them appropriately can improve image quality, depending on your output device, media, and resolution.

The three main options affected by the halftone settings you choose are:

• the shape of the dots created—see Selecting Dot Shapes on page 5

• the frequency of the dot pattern created—see Selecting Screen Ruling on page 6

• the angle of the dot pattern created—see Selecting Screen Angles on page 7

Selecting Dot ShapesThe following section describes common dot shapes available on the RIP.

Your choice of dot shape (also called spot function) affects print reproduction quality. To complement the types of images you print, choose dot shapes carefully.

Round The round dot is a commonly used dot shape that gives a smooth appearance in highlight and midtone areas. It is often used for imaging flesh tones and for images with high- and medium-key detail. Dot gain and tonal jumps are potential problems in the shadows, because the white space at the center of four adjoining round dots may fill with additional ink as the dots grow and begin touching. However, CreoScitex-developed SQUAREspot thermal technology provides accurate and stable imaging and so shadow detail is preserved remarkably well on press.

Figure 2: Round dot shape



Euclidean The euclidean dot is a general-purpose dot shape that reduces dot gain in the shadow areas. However, this dot shape creates a tonal jump at 50% where the corners of the checker board touch, causing excess ink to bridge between the dots. The euclidean dot shape is used for general applications, where the midtone tints are not critical to the image. It is particularly suited to high- and low-key images.

Figure 3: Euclidean dot shape

EllipticalPThe ellipticalP dot shape can be used to avoid the sharp transition at 50% that is characteristic of the euclidean dot shape. This is an excellent dot shape for general use. However, it is not suitable for printing flesh tones because the chaining of the elliptical dots at 40% and 60% may cause visible streaking in flesh tones under certain printing conditions.

Note: A variant of ellipticalP is elliptical1.

Figure 4: EllipticalP dot shape

Selecting Screen RulingAnother way to improve the quality of halftoning is to increase the halftone screen ruling or frequency—that is, the frequency with which the image is covered by halftone cells. Increasing screen ruling yields a greater concentration of dots in smaller halftone cells. As halftone ruling or frequency increases, so does dot gain. This is because a greater percentage of light is trapped in the tighter spaces between the dots.

Halftone Parameters 7


Selecting Screen AnglesSelecting accurate screen angles is critical to the quality of four-color process halftone printing. There are a number of reasons for choosing screen angles carefully:

• Choosing optimal screen angles minimizes inaccuracies and moiré patterning in screens when they are superimposed. The RIP defaults to angles that are nominally 30° apart, and optimizes them automatically for each screen frequency encountered.

• Overriding a set of angles requested in a PostScript job is especially useful if the job requests a set of angles that is not optimized for your output device. The RIP has a mechanism to override all incoming screening, as do electronic page imposition applications such as ScenicSoft Preps.

• Choosing screen angle sets carefully optimizes reproduction of multiple page publications or any element, such as individual images, pages, and forms.

Moiré PatterningYou can minimize moiré patterning by choosing screen angles that are 30° apart from each other. Because there are only three positions that are 30° apart in any orientation of the coordinate system, you must screen additional separations 15° between two other colors. If those color pairs are dominant in the image, objectionable interference patterns or moiré may seriously affect the quality of image reproduction.

A good choice of angles for general use with color separations in offset lithography work is a set in which colors are separated by 30°—for example, 15°, 75°, 0°, and 45° for CMYK (and related sets using these angles plus or minus multiples of 90°). For elliptical dots, a separation of 60° is recommended, leading to angles of 105°, 75°, 0°, and 135° for CMYK. Because yellow has the least contrast of the process colors, it is important to screen it 15° from other colors.

However, yellow at 0° may produce moiré in flesh tones because it interferes with magenta at 75°. To solve this problem, you can:

• screen yellow at 30°, or magenta at 45° and black at 75°

• screen yellow and black at 45°

• change the yellow frequency to a higher value (at least +8%)



This method of evaluating color content in images lets you choose angle sets that minimize moiré effects. For color printing with more than four color separations, you can often use the same angles for complementary colors because they are seldom needed in the same area of the image.

Note: Because black and magenta are the highest contrast colors, one of them should be screened at 45° to avoid jagged edges or horizontal and vertical edges.

Stochastic ScreeningStochastic, or FM, screening is a digital screening process that uses randomly placed dots instead of traditional halftone dots to create images. Stochastic screening is no different than conventional or amplitude modulation (AM) screening in that gray level reproduction is achieved by varying the number of pixels turned on in a halftone cell. However, halftone cells in stochastic screening are arrived at in an entirely different manner, and print reproduction is significantly different.

In stochastic screening, screen images are created with small clusters of dots of approximately 14 to 30 microns, often on the same scale as the output device pixels. Stochastic screens are constructed by placing output device pixels in a seemingly random pattern. In contrast, conventional screens are constructed with ordered pixels to create variable-sized, symmetrical dot shapes arranged in a geometric grid of halftone cells.

Halftone Versus Stochastic ScreeningConventional halftone screening achieves tone gradations by varying the size or amplitude of dots, while their frequency remains constant. Stochastic screening uses dots of similar size, and varies the frequency and location of those dots to achieve variations in the gray scale. Although conventional screening has limitations, such as moiré patterns and rosette structure, the regularity of the dot patterns produces smooth, uniform, and homogenous tonal appearance.

Figure 5 shows enlarged views of halftone and stochastic screens.

Stochastic Screening 9


Figure 5: Halftone and stochastic screen samples

Stochastic dots are pseudo-randomly placed to avoid problems associated with the regular patterns encountered in conventional screens. Although the stochastic clusters are optimized for smooth tonal appearance, irregularities in the spot clusters result in visual noise or graininess. The nature of this noise is complex and can be attributed to variations in cluster spacing and size, and to the non-periodicity of the clusters.

As the frequency of the stochastic clusters increases, the graininess or variability in the screen becomes less visible. For example, it is impractical to make plates from film with very small clusters of dots, because vacuum draw, exposure, and processing can introduce variations to the size of the reproduced clusters. This adds up to significant changes in tint reproduction, which is further compounded on press by additional physical and optical dot gain.

Computer-to-plate technology makes this easier, but gaussian laser spots produce clusters with slightly fuzzy edges, which are not accurately reproduced through the processor. CreoScitex SQUAREspot thermal laser technology provides consistent, stable exposure of each cluster, resulting in less sensitivity to processor variations.

Halftone screening Stochastic screening



Benefits of Stochastic ScreeningStochastic screening uses a random approach that offers a number of improvements over conventional halftone screening.

No Moiré or Rosette Patterns

The random arrangement of dots in stochastic screening means that there are no directional patterns in the screen, and no screen angles. The rosette patterns found in multicolor, conventional halftone printing do not exist in a stochastic screen image. This improves gray level simulation and the rendering of fine detail that may otherwise be obscured by rosettes.

Note: With high levels of Gray Component Replacement (GCR), the rosette is more visibly objectionable than a stochastic screen.

Without directional patterns, stochastic screens avoid the moiré patterns that occur with conventional screens when separations clash with each other or the screen clashes with patterns, such as herringbone or fabrics, in the image itself.

The absence of periodicity also simplifies the reproduction of duotones and multicolor systems, such as High-Fidelity (Hi-Fi) Color or Hexachrome.

Misregistration Tolerance

Small misregistrations of coarse, conventional rosette structures (150 lpi) may cause color shifts when dots overprint each other. Stochastic screens appear to be less sensitive to these misregistrations.

High Quality at Low Resolution

The small dot used in stochastic screening allows high-quality screens to be rendered at lower output resolutions without losing gray levels. By imaging at lower resolutions, you can achieve higher output speeds and productivity.

Improved Rendition of Detail

The printability of a conventional screen is due to the size of its highlight dots. A stochastic screen with equivalent printability imposes a much finer matrix of halftone dots on the image than its equivalent conventional screen.

Benefits of Stochastic Screening 11


Although high-frequency conventional screens can be used very effectively to improve the rendition of detail, they are ultimately limited by their halftone cell size, which is a function of device resolution. Stochastic screens can achieve much higher frequencies at the same output resolution. Any image with fine detail, particularly one with subtle textures, will benefit from this. However, remember that smooth surfaces may not be enhanced by coarser stochastic screens.

High-frequency conventional and stochastic screens are particularly dependent on the quality of the output device. The device’s ability to render detail is important for both desirable and undesirable artifacts, whether they are in the image, or the grain of the media, or the result of imperfect imaging. For this reason, Staccato screens have been carefully chosen to work optimally with CreoScitex SQUAREspot thermal imaging technology. As this technology matures, higher frequency and finer feature screens will become available.

Smooth Tone Rendering

Stochastic screens do not display the tone jump common in conventional screens where the dots touch. Because stochastic halftone cells are relatively large compared to conventional halftone cells, there are no limitations on the number of gray levels that can be reproduced.

Tone Stability With Increased Inking

Despite their high-gain characteristics, stochastic screens have shown increased tone stability over a wide range of inking levels. Tests have further shown that finer cluster sizes, particularly 20 µm, are even more stable as inking levels are increased.

It is likely the small, consistently sized clusters carry a thinner film of ink than conventional screens—that is, they are less susceptible to excessive physical dot gain on press. As inking levels reach a maximum and screens begin to plug, stochastic screens exhibit a gradual decline in print contrast whereas conventional screens exhibit a rapid decline in print contrast.

Smoother Overprints

Tints with three and four colors overprinted, such as earth tones and neutral grays, often exhibit blotchy print reproduction when screened with AM screens.



This effect is caused by inconsistent wet trap on the press when varying sizes of AM dots result in varying ink film thickness being transferred to the media. This effect is accentuated by the application of several layers of wet ink, one on top of the other, to yield blotchy color reproduction.

FM screens transfer a more uniform ink film thickness and eliminate this problem.

First- and Second-Order FM ScreeningFirst-order FM screens represent different tones by varying the number of fixed-size dots and distributing them in a random fashion. They deliver fine detail and eliminate subject and screening moiré. However, the small size and tight spacing of first-order dots contribute to dot gain, and, despite their fine structure, the random dispersion of dots may produce a visibly grainy pattern in flat tint areas.

Like their first-order FM predecessors, second-order FM screens render the same fine detail and eliminate moiré. However, by clustering the dots into orderly patterns in the midtones, they produce less grain and less dot gain than first-order FM screens. The clustered dots help moderate dot gain by minimizing edge effects and midtone plugging, and their more regular pattern subdues grain visibility.

First- and Second-Order FM Screening 13


Figure 6: First- and second-order stochastic screens

First-order stochastic

Second-order stochastic



Combining ScreensStaccato allows you to mix conventional and stochastic screens on the same media to exploit the advantages of both screen types. For example, you may apply conventional screens when smooth tonal appearance is critical, and apply stochastic screens when moiré patterning is an issue.

Screening can be specified for individual elements, such as images, pages, or printing forms. You can also apply stochastic screens to one or more separations. For example, by applying a stochastic screen to the yellow and/or cyan separation, you can eliminate screening moiré and objectionable rosette structure.

However, our experience shows that tonal balance and hue control is more difficult to achieve when FM and AM screens are mixed. AM screens respond differently than FM screens to changes in inking. Typically, we find that boosting inking levels causes AM screens to have greater dot gain than FM screens, making it difficult to find the tonal balance that produces the correct hues, images, or pages when both screens are used together.


Staccato Overview

What Is Staccato? .............................................................................16

How Staccato Works.........................................................................18

Staccato Requirements......................................................................18

16 Chapter 2 – Staccato Overview


What Is Staccato?Staccato is a CreoScitex-developed stochastic, or FM, screening software solution. The combination of Staccato and CreoScitex-developed SQUAREspot thermal imaging technology gives you a level of control in the printing process that makes stochastic screening viable for routine presswork.

The demands stochastic screening places on time and equipment mean it is not usually a practical solution for everyday print production. It is difficult for many printers to deliver stochastic screening with conventional output devices because these devices do not offer the control required in the calibration, development, and platemaking processes. Staccato, however, makes FM screening a practical option for your routine presswork. You can also mix Staccato screens with conventional screens.

Staccato offers the following screening benefits:

• optimized screening

• consistent printing conditions

• maximum control

• output versatility

Optimized ScreeningStaccato optimizes screening for dot gain, printability, and smoothness under a variety of printing conditions. It eliminates subject and screening moiré, as well as rosette patterns, gray-level limitations, contouring, shade stepping, and tone jumps in blends by utilizing unique screen patterns for C, M, Y, and K separations. Unlike conventional screens, Staccato has less color shift if screens are misregistered and improves the rendition of fine detail.

Consistent Printing ConditionsStaccato produces stable tones and print contrast in high-density inking situations. It also caches screens so that the same halftones are produced on every print.

You can normalize dot gain to standard printing conditions by applying one of the Staccato default calibration curves—that is, pre-built calibration curves—supplied with Harmony calibration software. You can

What Is Staccato? 17


also use Harmony to build custom calibration curves tailored to your particular printing environment. By applying these custom calibration curves , you can optimize Staccato for specific print requirements.

Staccato optimizes print reproduction using CreoScitex-developed SQUAREspot thermal imaging, and takes advantage of its specially designed, high-quality thermal imaging mode.

Maximum ControlYou control Staccato from the RIP. You can also control Staccato from desktop publishing applications to screen individual forms, pages, and EPS images, or on a separation-by-separation basis. Staccato screening does not affect RIPing time.

Output VersatilityStaccato includes a selection of screens with dot sizes ranging from 20 µm for the finest sheetfed work to 70 µm for coarser packaging work.

Staccato screening is based on Harlequin Dispersed Screening (HDS), which includes screening patterns carefully selected for optimal performance in the digital workflow environment. Staccato screens can be imaged at all resolutions available on CreoScitex-developed output devices: 1200, 1600, 2400, and 3200 dots per inch (dpi).

18 Chapter 2 – Staccato Overview


How Staccato WorksThe following steps describe a typical Staccato workflow.

1. You apply Staccato screens to one of the following elements in a desktop publishing application:

• individual images on a page

• an entire page of a printing form

• an entire printing form

• a separation

This degree of flexibility lets you mix conventional screens with Staccato screens to take advantage of the benefits of each type of screening.

2. After Staccato screens are applied by the RIP, files are generated.

3. The RIP interprets and applies Staccato screens when it encounters Staccato-specific parameters.

Staccato RequirementsTo use Staccato, you must have software and firmware that supports it already installed. For more information about Staccato software and firmware requirements, please contact a service representative.


Getting Started

Installing Staccato .............................................................................20

Licensing Staccato on Allegro Workstation 2.0 ..................................21

Installing Staccato on Allegro or Platesetter Workstation ...................24

Generating a PPD File........................................................................32

20 Chapter 3 – Getting Started


Installing StaccatoDepending on your workflow, you may need to license or install Staccato before you can use it.

• If you have a Prinergy system, Staccato comes preinstalled. If you have Prinergy 2.0, the system administrator needs to license Staccato before you can use it. For information on licensing Staccato for Prinergy, see your Prinergy system administration documentation.

You can skip this chapter if you have Prinergy.

• If you use iMPAct workflow with Allegro Workstation 2.0 and either Trendsetter Console or Platesetter Console, you need to license Staccato before you can use it.

See Licensing Staccato on Allegro Workstation 2.0 below.

• If you use iMPAct workflow with Allegro Workstation software release 1.2 or Platesetter Workstation software release 1.7 (running Allegro RIP revision 4.1r6a2), you need to install Staccato.

See Installing Staccato on Allegro or Platesetter Workstation on page 24.

Licensing Staccato on Allegro Workstation 2.0 21


Licensing Staccato on Allegro Workstation 2.0Staccato comes with Allegro Workstation 2.0 and either Platesetter Console or Trendsetter Console. However, to use Staccato, you need to license it first.

Platesetter ConsoleThis procedure describes how to license Staccato on Platesetter Console.

To License Staccato on Platesetter Console:

1. Have your Staccato License Key available.

The Staccato License Key is located on the front cover of the Staccato User Guide.

Note: If you can’t find your license key, contact a service representative.

2. Start Platesetter Console.

For more information, see your Platesetter Console documentation.

3. Click the Take Offline button in the top right-hand corner to take the workstation offline.

Note: If the Platesetter Console menu bar is not displayed, press CTRL+ALT+C to display the menu.

4. From the Configuration menu, select Workstation.

The Configure Workstation dialog box displays.



Figure 7: Configure Workstation dialog box

5. Verify that the Allegro Dongle Security Code diplayed on the Configure Workstation dialog box is the same as the Allegro Dongle Security Code on the Allegro Workstation 2.0 CD.

6. In the Staccato License Key box, type the Staccato License Key.

The license key is a number and letter sequence like the following:

TNS-TUK-SL9-FD

You must type the letters (letters must be capitalized) and numbers exactly as shown in the license key on your Staccato User Guide. Type the hyphens and letters without any spaces between them.

7. Click OK. Your license key is verified now.

Staccato licensing is complete.

8. Click the Put Online button in the top right-hand corner to put Allegro Workstation back online.

Licensing Staccato on Allegro Workstation 2.0 23


Trendsetter ConsoleThis procedure describes how to license Staccato on Trendsetter Console.

To license Staccato on Trendsetter Console:


The Staccato License Key is located on the front cover of your Staccato User Guide.

Note: If you can’t find the Staccato License Key, contact a service representative.

2. Start Trendsetter Console.

For more information, see your Trendsetter Console documentation.

3. From the Allegro RIP menu, clear Start Inputs to take Allegro RIP offline.

Note: When selected, Start Inputs has a check mark beside it. Click the Start Inputs option to clear or select it.

4. From the Trendsetter menu, select Workstation Configuration.

The Configuration dialog box displays.

Figure 8: Configuration dialog box

5. Verify that the Allegro Dongle Security Code displayed on the Configuration dialog box is the same as the Allegro Dongle Security Code on your Allegro Workstation 2.0 CD.



6. In the Staccato License Key box, type the Staccato License Key.

The license key will be a number and letter sequence like the following:

TNS-TUK-SL9-FD

You must type the letters (letters must be capitalized) and numbers exactly as shown in the license key on the front cover of your Staccato User Guide. Type the hyphens and letters without any spaces between them.

7. Click OK. Your license key is verified now.

Staccato licensing is complete.

8. From the Allegro RIP menu, select Start Inputs to put Allegro RIP online.

Installing Staccato on Allegro or Platesetter WorkstationThe following procedure describes how to install Staccato software on Allegro Workstation or Platesetter Workstation. This procedure works only if the workstation has the following software installed:

Allegro Workstation software release 1.2(running Allegro RIP revision 4.1r6a2)

Or:

Platesetter Workstation software release 1.7 (running Allegro RIP revision 4.1r6a2).

PlateMaster release 1.2f, Service Pack 1

PlateMaster requires Windows NT 4.0 and an upgrade to Archiver software release 1.2f, Update 2

Important: You can only install Staccato on a workstation with the dongle that matches your Allegro serial number. Your licensed copy of Staccato will not work with any other dongle.

Important: If you want to run both Harmony and Staccato on your workstation, you should install Harmony first. Harmony curves will install on your workstation only if Harmony is installed before Staccato.

Installing Staccato on Allegro or Platesetter Workstation 25


To install Staccato on your workstation:


The Staccato License Key is located on the Staccato CD.

Note: If you can't find your Staccato License Key, contact a service representative.

2. Ensure that all software applications are closed, including the workstation software.

3. Insert the Staccato software CD in the workstation CD drive.

4. Run setup.exe.

The Staccato Welcome dialog box displays.

Figure 9: Welcome dialog box

5. Click Next.

The Select Install Option dialog box displays.



Figure 10: Select Install Option dialog box

6. Choose one of the following:

• If only one software application is detected, click Next.

• If more than one software application is detected, select the appropriate application, then click Next.

The Staccato License Key dialog box displays.

Figure 11: Staccato License Key dialog box

Note: The setup program detects installed workstation software applications and their locations; these are displayed in the Select Install Option dialog box.



7. In the SLK box, type your Staccato License Key.

The license key will be a number and letter sequence similar to the following:

SY7-GZ7-U52-LX7-ITP-L52-KHV-YNN-LW

You must type the letters and numbers exactly as shown on your CD. Type the hyphens and capital letters without any spaces between them.

Note: Staccato will not proceed with the installation unless your license key is valid.

8. Click Next.

If you have Harmony installed, a Warning box displays. The warning reminds you that a PPD file has not been copied to the Harmony application folder. To create a PPD file for use with Harmony, you must refresh the media configuration of your workstation.

Figure 12: Warning box (creating PPD file for Harmony)

• Read the message, then click OK.

The Select Components dialog box displays.

Figure 13: Select Components dialog box



If you have do not have Harmony installed, your Allegro RIP Calibration Manager database is updated with Staccato calibration curve sets.

If you have Harmony installed, Staccato calibration curve sets are copied to the Harmony application folder.

Figure 14: Select Components dialog box (Harmony installed)

9. Ensure the check boxes beside the components you want to install are selected, then click Next.

Note: If Staccato is already installed on your system, the Update Allegro with Staccato calib. curves check box is cleared.

If your license key is correct, the Choose Destination Location dialog box displays.



Figure 15: Choose Destination Location dialog box

10. Ensure the location is correct, then click Next.

If your license key is incorrect, an information message displays. The message displays the incorrect license key you typed.

Figure 16: Information message

If you receive this message, check that you typed the license key exactly as written on your CD in the Staccato License Key dialog box. If you made an error typing the license key, correct the error, and click Next again.

The Confirm Installation dialog box displays.



Figure 17: Confirm Installation dialog box

If you have Harmony installed, notice that calibration curves will be copied to the harmony application folder.

Figure 18: Confirm Installation dialog box (Harmony installed)

11. Ensure your settings are correct, then click Next to begin the Staccato installation.

If you have Harmony installed, the Import Staccato 2.0 calibration curves dialog box displays.



Figure 19: Import Staccato 2.0 calibration curves dialog box

• Read the message, then click OK.

The Staccato calibration curve sets are copied to a database file, staccato_2.0.hmy, in the harmony application folder.

If you do not have Harmony installed, the Staccato calibration curves are copied directly to the Allegro RIP Calibration Manager database.

When the installation is complete, the Staccato 2.0 Setup dialog box displays.

Figure 20: Staccato 2.0 Setup dialog box

12. If you do not have Harmony installed, go to step 13.

If you have Harmony installed, the Staccato 2.0 Setup dialog box includes a check box that lets you choose to automatically start Harmony when you exit setup. Select the Do you want so start Harmony now? check box.

Important: To use Staccato calibration curves, you must import the desired curves from the staccato_2.0.hmy file into the Harmony database. For information on importing curves into the Harmony database, refer to the Harmony User Guide.



Figure 21: Staccato 2.0 Setup dialog box (Harmony installed)

Running Harmony now imports the Staccato calibration curves into the Harmony database.

13. Click Finish to exit the Staccato installation.

Write Down the License KeyPlease keep a record of your Staccato License Key. If you upgrade your Allegro RIP software, you may need to re-enter the license key. You can do this without help from a service representative if you have the license key.

Generating a PPD FileOnce you successfully license or install Staccato, you should generate a new PostScript Printer Description (PPD) file that includes Staccato dot shapes. For more information on generating PPD files, see your Console documentation.

Note: If the installation is unsuccessful, please ensure the Allegro serial number displayed in the Staccato License Key dialog box matches the Allegro serial number located on your Staccato CD. For more information, call a service representative.


Staccato Screens

Selecting Staccato Screens ................................................................34

Staccato Screen Characteristics .........................................................34

First-Order Screens ............................................................................36

Second-Order Screens .......................................................................37

Dot Gain...........................................................................................41

Applying Staccato Screens.................................................................42

34 Chapter 4 – Staccato Screens


Selecting Staccato ScreensStaccato screening is designed to meet the needs of most printers; it offers a family of screens for each output device resolution. This means you can use Staccato with all printing applications. For more information on Staccato screens, see Staccato Screen Characteristics below.

In general, with higher-quality printing processes, you can use a finer Staccato screen. Your selection of a Staccato screen for a printing job, particularly on conventional film, is usually based on the following criteria:

• physical characteristics of your output device

• output media

• printing and press environment

• ink and paper type

Staccato Screen CharacteristicsThis section identifies the families of Staccato screens that are available with CreoScitex-developed output device resolutions. It also describes physical characteristics of each screening family.

The following table describes Staccato screens. Note that in the table, clusters per inch indicates the screen’s ability to render detail. It is comparable to AM screen rulings measured in lines per inch (lpi).

Staccato Screen Characteristics 35


Table 1: Staccato screens

The Staccato screening family includes both first- and second-order screens. The Staccato screening family has the flexibility to meet the range of stochastic screening needs of publication, packaging, and commercial

Staccato Screen

Output Resolution(dpi)

High-light(µm)

Mid-tone Cluster Size(µm)

AverageCluster Size(µm)

Approximate Midtone Frequency(clusters per inch)

Staccato 20 1600 15.9 23.8 19.8 320

2400 21.2 23.8 22.5 385

3200 15.9 23.8 19.8 320

Staccato 20.1 1200 21.2 21.2 21.2 425

(1st order FM) 2400 10.6 15.9 13.2 320

Staccato 25 1200 21.2 31.8 26.5 240

1600 23.8 31.8 27.8 275

2400 21.2 31.8 26.5 240

3200 23.8 29.8 26.8 320

Staccato 35 1200 31.8 42.3 37.0 205

1600 31.8 35.7 33.7 255

2400 31.8 39.7 35.7 240

3200 31.8 35.7 33.7 255

Staccato 50 1200 42.3 63.5 52.9 120

1600 47.6 59.5 53.6 160

2400 47.6 52.9 50.3 140

3200 47.6 63.5 55.6 160

Staccato 70 1200 63.5 79.4 71.4 120

1600 63.5 71.4 67.5 128

2400 63.5 84.7 74.1 120



printers.

First-Order ScreensStaccato first-order screens, like other traditional FM screens, represent different tones by varying the number of dots of a fixed size, and distributing the dots in a random fashion. They deliver fine detail and eliminate subject and screening moiré.

However, the small size and tight spacing of first-order dots contribute to dot gain. For more information, see Dot Gain on page 41. The random dispersion of dots may also produce a visibly grainy pattern in flat tint areas, even though the structure of dots is fine rather than coarse.

You can distinguish a first-order screen by its screen number, which has the extension .1, for example, Staccato 20.1.

Staccato 20.1Staccato 20.1 is a first-order FM screen that uses a nominal dot size of 20 µm. The screen uses 20 µm halftone dots throughout the whole tonal scale. The midtone frequency of Staccato 20.1 is equivalent to 425 lpi. This stochastic screen is suitable for high-quality sheetfed printing on coated stock in commercial and premium printing environments.

Figure 22: Staccato 20.1

Second-Order Screens 37


Second-Order ScreensStaccato second-order screens, like first-order screens, render fine detail and eliminate moiré. However, by clustering midtone dots into orderly patterns, second-order stochastic screens produce less grain and less dot gain than first-order screens. The clustered dots moderate dot gain by minimizing edge effects and midtone plugging, and the more regular screen pattern subdues grain visibility.

Staccato 20Staccato 20 is a second-order FM screen that uses a nominal dot size of 20 µm with a midtone frequency of 385 clusters per inch. Staccato 20 offers the printability of Staccato 20.1 but with less grain, less dot gain and more consistent tonal reproduction. This stochastic screen is suitable for high-quality sheetfed printing on coated stock in commercial and premium printing environments.

Figure 23: Staccato 20

Staccato 25Staccato 25 is a second-order FM screen. With an average dot size of 25 µm, this screen uses 20 µm dots in the quartertones and has a midtone frequency of 240 clusters per inch. Staccato 25 offers the printability of Staccato 35 without the visible grain. This stochastic screen is suited to quality web printing on coated stock in high-volume, publication-style printing environments.




Staccato 35Staccato 35 is a second-order FM screen. With an average dot size of 35 µm, it uses 30 µm dots in the highlights and has a midtone frequency of 240 clusters per inch. This large, structural screen increases printability in the highlights, midtones, and shadows. Because Staccato 35 is visibly grainy on higher-grade paper stock, it is suitable for web printing on lower-grade coated and uncoated stocks in high-volume printing environments.

Second-Order Screens 39



Staccato 50Staccato 50 is a second-order FM screen. With an average dot size of 50 µm and a midtone frequency of 140 clusters per inch, this screen is suitable for applications where large features are required, or where the normal viewing distance is greater than 30 inches.




Staccato 70Staccato 70 is a second-order FM screen. With an average dot size of 70 µm and a midtone frequency of 120 clusters per inch, this screen has a visible structure at normal viewing distances. This makes Staccato 70 suitable for applications where large features are required, such as screen printing, or where the normal viewing distance is greater than 30 inches.


Dot Gain 41


Dot GainDot gain, also called tone value increase, is a normal part of the printing process. Dot gain compensation or tonal calibration, is the process of measuring, characterizing, and normalizing the printing of halftone screens on press and proofing devices. When applied, the resulting calibration curves normalize your press and proofing device so that they both print with the same overall dot gain characteristic.

There are two types of dot gain: physical and optical. Physical dot gain refers to a change in the physical size of the dots during tone reproduction. Optical dot gain refers to the additional light that is trapped in the white paper structure at the perimeter of the halftone dots, resulting in a perceived darker tint. Optical dot gain is greater on uncoated stock and increases with the frequency or fineness of the halftone structure. This is because a greater light percentage is trapped in tighter spaces between dots.

Tonal CalibrationStochastic screens are high-frequency screens and exhibit excessive optical dot gain on press. Therefore, characterization and compensation of that dot gain is essential to the reproduction of any stochastic screen. This process is often referred to as tonal calibration or dot gain compensation.

Harmony calibration software lets you achieve accurate results on your output. Using Harmony, you can create customized calibration curves for your particular printing needs and environment. You can build Harmony calibration curves to use with Staccato and conventional screening. Alternately, you can use one of the default calibration curves supplied with Harmony if you don’t want to build your own curves. Harmony includes a default calibration curve for each Staccato screen.

For more information on Harmony and tonal calibration, see your Harmony documentation.



Applying Staccato ScreensYou can easily invoke a Staccato screen in many PostScript desktop publishing applications by manually selecting the line screen value equivalent to the Staccato spot size you want to use. For example, to apply a Staccato 20.1 screen, use 20.1 lpi in the screen ruling field of the desktop publishing application.

Figure 28: Applying Staccato screens using line screen values (Adobe Illustrator)

Figure 5.1 shows how you can apply a Staccato 20.1 screen in Adobe Illustrator by simply typing the lpi value 20.1 in the Frequency box.

For more information about applying Staccato screens, see the Staccato documentation for your specific workflow.

Line screenvalue

Important: As long as another application does not override screening, specifying 20.0, 20.1, 25.0, 35.0, 50.0, or 70.0 lpi in your desktop publishing application automatically invokes the corresponding Staccato screen.

Note: To print with a low lpi AM screen instead of a Staccato screen, simply select a screen ruling that is close but not equal to Staccato spot sizes—that is, 20.0, 20.1, 25.0, 35.0, 50.0, or 70.0 lpi. For example, if you want to use a 20 lpi screen, you can select one of the following: 19.5, 19.9, 20.2, or 20.5 lpi. The RIP optimizes this request to a 20 lpi screen rather than invoking a Staccato screen.

Glossary


Allegro RIP A software application that creates a rasterized image from a PostScript file. It is a PostScript Level 2 software RIP.

amplitude modulation(AM) screening

See halftone screening.

calibration Setting equipment to produce desired results.

calibration curve The curve that graphically represents how much Harmony needs to compensate for tint values specified in the digital file when the file is RIPed so that the target is achieved on the final deliverable.

cluster See dot cluster.

clusters/inch Dot clusters per inch. A measurement of the number of dot clusters per inch in a screen.

CMYK A color representation scheme (or color space) where cyan, magenta, yellow, and black are combined to create full-color images.

color separation A monochrome image that describes a component of a color image that has been described using a particular color space. In printing, images are typically depicted in the CMYK space, leading to four separated pages for each full-color page.

continuous tone image An image that contains gradient tones.

conventional screening See halftone screening.

density A measurement of the ability of light to pass through or reflect off a material. The density of a solid black patch is called the maximum density (or dmax). Density is measured using a densitometer.

dimension The number of pixels in a halftone cell.

dot The smallest, most basic element of a halftone.

dot cluster A formation of regular or irregular shapes through a clustering of pixels.

44 Staccato User Guide


dot gain On halftone output, the absolute percentage change in the actual (physical dot gain) and perceived (optical dot gain) size of a halftone dot as it goes through the halftone reproduction process. For example, 5% dot gain means that 5/100 more light is being absorbed, regardless of the tint that is being measured. In other words, 5% dot gain on a 1% tint means an effective dot area of 6%; 5% dot gain on a 50% tint means an effective dot area of 55%.

Dot gain happens during various phases of the halftone reproduction process.

See also optical dot gain and physical dot gain.

dot gain calibration See tonal calibration.

dot gain compensation See tonal calibration.

dot shape The shape in which dots on the image are generated.

See also elliptical dots and euclidean dots.

dpi Dots per inch. A unit of measurement that signifies the number of laser dots that can be printed in an inch. The higher the number, the higher the resolution of the output device.

elliptical dots The elongated oval-shaped dot often used in conventional screening methods.

euclidean dots The dot shape most common to conventional screening methods. Euclidean dots appear round in highlights and shadows and square at 50%.

Encapsulated PostScript (EPS)

EPS is a subset of the PostScript language that allows images to be described in a format which can be imported into other documents. EPS images are independent of the format of the document, and so may be imported into documents using a wide variety of applications from within the application itself, or into other PostScript-language page descriptions.

exposure head Located inside the output device, this uses a laser to write data to media. Also called an imaging head.

form A unit of organization that consists of all the images that will be mounted on the press at one time, and then run and folded together. A form includes a number of files. Also called a signature.

Glossary 45


frequency-modulated(FM) screening

See stochastic screening.

GRACol General Requirements for Applications in Commercial Offset Lithography. This is a standard set of specifications for separations, proofs, and color printing designed for sheetfed printers.

gray balance The values for C, M, and Y that produce a neutral gray with no dominant hue.

Gray Component Replacement

When three color inks overprint, the two predominant colors determine the color’s hue and the third color, or gray component, indicates the final color’s grayness or saturation. An amount of the three colors equivalent to the gray component can be removed from the color and replaced with black ink in order to increase color saturation, speed up makereadies on press, and improve print consistency.

green exposure head A CreoScitex light imaging option that uses a frequency-doubled YAG laser to image visible light-sensitive media. Platesetters, VLF Platesetters, and VLF Trendsetters may have a green exposure head.

halftone A complex image that has been broken up into a series of very small dots in order to reproduce it. Text and visuals are represented as dots within a grid. The grid, called a screen, is composed of halftone cells. An example of a halftone image is a newspaper photograph.

halftone cell A single dot in a halftone image.

halftone image An image composed of dots that vary in size but are constant in spacing, giving the appearance of different colors or shades of grey.

halftone screening The method of screening whereby a continuous tone image is broken down into a series of dots of varying sizes that are placed in a rigid grid pattern. Color images are separated into the four process colors and individual screens of color are created and then skewed at angles to reproduce the image in print. Also called conventional screening.

Harmony CreoScitex-developed calibration software.

HDS (HarlequinDispersed Screening)

Harlequin’s FM screening method that produces high-quality output and offers freedom from both cross-screen and object moiré.

Hexachrome A six-color process printing system from Pantone Inc.



Hi-Fidelity Color A color specification and printing system that enhances the traditional four-color process (CMYK) system, for example, Hexachrome. Also called Hi-Fi Color.

highlight The lightest, or whitest, parts of an image.

HRX imaging head A CreoScitex multi-mode imaging option that uses a frequency-doubled YAG laser to image visible light-sensitive media a high resolutions.

imaging head See exposure head.

imposition A means of arranging a number of pages on the front and back of a press sheet to ensure the correct order after the printed sheet is folded.

lpi Lines per inch. The number of lines per inch in a screen grid. In metric measurement, it is referred to as lines per centimeter (L/cm).

The greater the number of lines per inch, the sharper the image.

See screen ruling.

midtone The tonal range between highlights and shadows in an image.

midtone jump A printing artifact that occurs in vignettes around the 50% mark, where the halftone dots begin touching, causing excessive ink to be transferred to the medium. To the eye, a dark band of color appears in place of a smooth transition.

moiré pattern A printing effect that occurs when color separations screened with periodic halftones produce interference patterns when superimposed. By maintaining 30° between screens, moiré can be minimized. Moiré also occurs when a single screen frequency interferes with patterns or lines in the image itself. This is referred to as subject or object moiré.

optical dot gain Additional light that is trapped in the white paper structure at the perimeter of halftone dots, resulting in a perceived darker tint. See also dot gain.

output Any data that is transferred to another device, such as a laser printer, a video display, or a platesetter.

output device Any device that plots data to hard copy, such as a laser printer, a platesetter, or an analog or digital proofer.

physical dot gain A change in the physical size of dots during tone reproduction. See also dot gain.

Glossary 47


pixel Picture element. The smallest distinct unit of a bitmapped image displayed on a screen.

PDF Portable Document Format defined by Adobe.

Platesetter Console Software that runs a CreoScitex-developed automatic output device system. It provides the operator’s console, queueing management, raster image processor (RIP), and system control.

plugging A printing problem where ink fills in around halftone dots, causing a loss in shadow detail.

PPD file PostScript Printer Description file. This file contains information specific to the output device, such as medium size and the area of the medium—that can be imaged, that is, used during electronic imposition of PostScript files.

PostScript A page description language developed by Adobe Systems that is used to describe type and visual elements so that they can be printed on devices with PostScript interpreters.

PostScript file A file written in the PostScript page description language created from a native application file, such as QuarkXPress.

press response A measurable printed result for a given set of conditions—for example, different dot gain from different halftone screens.

Prinergy A PDF-based prepress workflow and content management tool that organizes prepress and plate production.

quarter tone The tonal range between highlights and midtones in an image.

recorder See output device.

registration The alignment of different films or printing plates to produce one printed image.

RIP Raster Image Processor. A standard term used to name software or devices that take an image and convert it into a bitmap for display on a computer screen or output on an output device.



rosette The pattern in which halftone cells are arranged in a separated image. The RIP can produce rosettes that have clear centers (on the right diagram, with the central dot removed) or dark centers (on the left diagram).

screen Invisible grid that is superimposed on an image.

screening The process of taking a continuous tone PostScript image and converting it into a digital halftone using a grid. The line frequency of the screen, which determines how finely or coarsely the image is represented, is set using lines per inch (lpi).

screen angle The angles at which the halftone screens are set when making screened images for printing halftones. Proper screen angles are critical for minimizing moiré patterns.

screen frequency The density of dots on the halftone screen, commonly measured in lines per inch (lpi). This is also called screen ruling.

screen ruling The number of lines per inch (lpi) on a halftone screen.

separation Refers to a color or layer in a file. A separation can be compared to film. There is one film for each color. For example, a basic CMYK job requires four films (four separations). Each spot color has its own film (its own separation). If multiple black films exist for a job, then multiple black separations are created for the job. All separations for a job must be registered to each other.

shadow The darkest parts of an image, represented by the largest dots in a halftone.

spot color A color that is created by mixing ink. It is not created using process colors.

spot function See dot shape.

stochastic screening A digital screening process that converts images into very small dots of equal size and variable spacing. Also called frequency-modulated (FM) screening.

Glossary 49


three-quarter tone The tonal range between midtones and shadows in an image.

tint A percentage of color that is represented in conventional screening by evenly-spaced dots of smaller dimension and in stochastic screening by less clustered tiny dots.

tonal calibration Setting equipment to reproduce tonal values to specified values on your final output (for example, a proof, press sheet or plate).

Harmony compensates for tone value increase by adjusting the size of dots imaged on the plate, digital halftone proof, press sheet, or film. Harmony compares the difference between a target and a current sample and determines the adjustment need to tint values specified in the file to achieve the target output.

Trendsetter Console Software that runs a Trendsetter-based output device system. It provides the operator’s console, queueing management, Allegro RIP, and system control.

vignette A design element in which gradations of color are displayed throughout an object in an image.

workstation A high-speed computer running the Windows NT operating system and the workstation software. It is the computer that provides the operator’s console, queueing management, raster image processor (RIP), and system control. The computer is connected to a local area network (LAN) over which it receives PostScript files.

Index


Aangle

screen, 4, 7applying

Staccato screens, 33, 42attention symbol, x

Ccalibration

tonal, 4, 41cells

halftone, 3color separation, 2combining screens, 14comments about manual, x

Ddot cluster, 8, 9dot gain, 4, 41dot gain calibration

See tonal calibration.dot shape, 3, 4, 5

ellipitcalP, 6euclidean, 6round, 5selecting, 5

dotshalftone, 3

Eelliptical dot shape, 6euclidean dot shape, 6

Ffirmware requirements, 18first-order screening, 12frequency

screen, 3, 6

Hhalftone

cell, 3, 6, 8, 11

dots, 3parameters, 5

halftone screeningdescription, 2

hardware symbols legend, xHarlequin Dispersed Screening, 17Harmony, 24

database, 31

Iinstalling Staccato

on Allegro or Platesetter workstation, 25

with Harmony, 24

Llegend

hardware symbols, xlicense key

locating, 21, 23licensing Staccato

on Platesetter Console, 21on Trendsetter Console, 23with Prinergy, 20

linescreen value, 42

Mmanual

sending comments, xmoiré

patterning, 7

PPlatesetter Console

licensing Staccato on, 21PPD file

generating, 32Prinergy

licensing Staccato with, 20

Rrosette

patterning, 10

round dot shape, 5

Sscreen, 3screening

combining screens, 14first- and second order FM, 12stochastic, 8

second-order screening, 12separation

color, 2software requirements, 18SQUAREspot thermal imaging, 16Staccato

definition, 16installing, 20licensing, 24workflow, 18

Staccato requirements, 18Staccato screens

applying, 42characteristics, 34first-order, 36second-order, 37selecting, 34Staccato 20, 37Staccato 20.1, 36Staccato 25, 37Staccato 35, 35, 38Staccato 50, 35, 39Staccato 70, 34, 35, 40

stochastic screeningbenefits, 10compared to halftone screening, 8description, 8

Tthermal imaging

SQUAREspot, 16tonal calibration, 41Trendsetter Console

licensing Staccato on, 23

staccato 2.0 user guide - resources.kodak.com · staccato.book page iii tuesday, june 26, 2001...

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