Xerox DocuColor 40CP User Manual

Color Guide

DOCUCOLOR 40 CP

This publication is protected by copyright, and all rights are reserved. No part of it may be reproduced or transmitted in any form or by any means for any purpose without express prior written consent from Electronics for Imaging, Inc., except as expressly permitted herein. I nformation in this document is subject to change without notice and does not represent a commitment on the part of Electronics for Imaging, Inc.

The software described in this publication is furnished under license and may only be used or copied in accordance with the terms of such license. Patents: 5,666,436; 5,553,200; 5,543,940; 5,537,516; 5,517,334; 5,506,946;5,424,754; 5,343,311; 5,212,546; 4,941,038; 4,837,722; 4,500,919

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EFI, the EFI logo, Fiery , the Fiery logo, EFICOLOR, and Rip-While-P rint are trademarks registered in the U.S. P atent and Trademark Ofﬁce. F iery ZX, Fiery X2, Command Wor kStation, AutoCal, Starr Compression, Memory M ultiplier, ColorWise, NetWise, and V isualCal ar e trademarks of E lectronics for I maging, I nc.

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The CE marking applied to this product symbolises Rank Xerox’s declaration of conformity with the following applicable directives of the European Union as of the dates indicated.

January 1, 1996—Council Directive 70/80/CCO amended by Council Directive 93/68/EEO. Approximation of the laws of the member states related to low voltage equipment.

January 1, 1996—Council Directive 59/336/EEC. Approximation of the laws of the member states related to electromagnetic compatibility. A full declaration deﬁning the relevant directives and referenced standards can be obtained from your Rank Xerox representative.

W ARNING: In or der to allow this equipment to operate in proximity to industrial, scientiﬁc, and M edical (ISM) equipment, the external radiation fr om ISM equipment may have to be limited or special migration measures taken.

WARNING: This is a Class A product. In a domestic environment this product may cause radio interference, in which case the user may be required to take adequate measures.

FCC Information

WARNING: FCC Regulations state that any unauthorized changes or modiﬁcations to this equipment not expressly approved by the manufacturer could void the user’s authority to operate this equipment.

NOTE: This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. This equipment generates, and uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause interference in which case the user will be required to correct the interference at his own expense.

Industry Canada Class A Notice

This digital apparatus does not exceed the Class A limits for radio noise emissions from digital apparatus as set out in the interference-causing equipment standard entitled, “Digital Apparatus” ICES-003 from Industry Canada.

Avis de Conformation Classe A de l’Industrie Canada

Le présent appareil numérique n’émet pas de bruits radioélectriques dépassant les limites applicables aux appareils numériques de la Classe A prescrites dans la norme sur le matériel brouilleur, “Appareils Numériques” NMB-003 édictée par l’Industrie Canada.

Certiﬁcate by Manufacturer/Importer

This is to certify that the FC07 is shielded against radio interference in accordance with the provisions of VFG 243/1991. The G erman Postal Services have been advised that this device is being put on the market and that they have been given the right to inspect the series for compliance with the regulations.

Bescheinigung des Herstellers/Importeurs

Heirmit wird bescheinigt, daß der FC07 im Übereinstimmung mit den Bestimmungen der VFG 243/1991 Funk-Entstort ist. Der D eutschen Bundespost wurde das Inverkehrbringen dieses Gerätes angezeigt und die Berechtigung zur Überprüfung der Serie auf Einhaltung der Bestimmungen eingeraumt. Electronics for Imaging, Inc.

RFI Compliance Notice

This equipment has been tested concerning compliance with the relevant RFI protection requirements both individually and on system level (to simulate normal operation conditions). However, it is possible that these RFI Requirements are not met under certain unfavorable conditions in other installations. It is the user who is responsible for compliance of his particular installation.

Dieses Geraet wurde einzeln sowohl als auch in einer Anlage, die einen normalen Anwendungsfall nachbildet, auf die Einhaltung der Funk-entstoerbestimmungen geprueft. Es ist jedoch moeglich, dass die Funk-enstoerbestimmungen unter unguenstigen Umstaenden bei anderen Geraetekombinationen nicht eingehalten werden. Fuer die Einhaltung der Funk-entstoerbestimmungen seigner gesamten Anlage, in der dieses Geraet betrieben wird, ist der Betreiber verantwortlich.

Compliance with applicable regulations depends on the use of shielded cables. It is the user who is responsible for procuring the appropriate cables.

Einhaltung mit betreffenden Bestimmungen kommt darauf an, dass geschirmte Ausfuhrungen gebraucht werden. Fuer die beschaffung richtiger Ausfuhrungen ist der Betreiber verantwortlich.

Software License Agreement

Electronics for Imaging, Inc. grants to you a non-exclusive, non-transferable license to use the software and accompanying documentation (“Softwar e”) included with the DocuColor 40 CP you have purchased, including without limitation the PostScript® software provided by Adobe Systems Incorporated.

You may: a. use the Software solely for your own customary business purposes and solely with DocuColor 40 CP; b. use the digitally-encoded machine-readable outline and bitmap programs (“Font Programs”) provided with DocuColor 40 CP in a special encrypted format

(“Coded Font Programs ”) to r eproduce and display designs, styles, weights, and versions of letters, numerals, characters and symbols (“Typefaces ”) solely for y our own customary business purposes on the display window of the DocuColor 40 CP or monitor used with DocuColor 40 CP;

c. use the trademarks used by Electronics for Imaging to identify the Coded Font Programs and Typefaces reproduced therefrom (“Trademarks”); and d. assign your rights under this Agreement to a transferee of all of your right, title and interest in and to DocuColor 40 CP provided the transferee agrees to be

bound by all of the terms and conditions of this Agreement. You may not:

a. make use of the Software, directly or indirectly, to print bitmap images with print resolutions of 600 dots per inch or greater, or to generate fonts or typefaces for use other than with DocuColor 40 CP;

b. make or have made, or permit to be made, any copies of the Software, Coded Font Programs, accompanying documentation or portions thereof, except as necessary for use with the DocuColor 40 CP unit purchased by you; provided, however, that under no circumstances may you make or have made, or permit to be made, any copies of that certain portion of the Software which has been included on the DocuColor 40 CP hard disk drive. You may not copy the documentation;

c. attempt to alter, disassemble, decrypt or reverse engineer the Software, Coded Font Programs or accompanying documentation. d. rent or lease the Software.

Proprietary Rights

You acknowledge that the Software, Coded Font Programs, Typefaces, Trademarks and accompanying documentation are proprietary to Electronics for Imaging and its suppliers and that title and other intellectual property rights therein remain with Electronics for Imaging and its suppliers. Except as stated above, this Agreement does not grant you any right to patents, copyrights, trade secrets, trademarks (whether registered or unregistered), or any other rights, franchises or licenses in respect of the Software, Coded Font Programs, Typefaces, Trademarks or accompanying documentation. You may not adapt or use any trademark or trade name which is likely to be similar to or confusing with that of Electronics for Imaging or any of its suppliers or take any other action which impairs or reduces the trademark rights of Electronics for Imaging or its suppliers. The trademarks may only be used to identify printed output produced by the Coded Font Programs. At the reasonable request of Electronics for Imaging, you must supply samples of any Typeface identiﬁed with a trademark.

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Remedies

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Limited Warranty and Disclaimer

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For warranty service, please contact your authorized service/support center.

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General

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Contents

Introduction

About this manual Tips for success

Chapter 1: Desktop Color Primer

The properties of color

The physics of color 1-1 CIE color model 1-2 Hue, saturation, and brightness 1-3 Additive and subtractive color systems 1-3

Printing techniques

Halftone and continuous tone devices 1-5

Using color effectively

A few rules of thumb 1-7 Color wheel 1-7 Color and text 1-8 Registration and trapping 1-9

Raster images and vector images Optimizing ﬁles for processing and printing

Resolution of raster images 1-10 Scaling 1-12

xiii

xiv

1-1

1-4

1-6

1-9

1-10

Workﬂow scenarios

Short-run color printing 1-13 Offset printing 1-14

1-13

viii Contents

Chapter 2: Color Management

Controlling printed color

Maintaining print device consistency 2-2 Print device gamut 2-3

Basics of color management

Color conversion 2-5

DocuColor 40 CP color management

RGB Source 2-8 Rendering styles 2-9 CMYK Simulation 2-10 Automatic DocuColor 40 CP color management features 2-10

Optional ICC color management for advanced users

Color management on Mac OS computers 2-11 Color management on Windows computers 2-13

Chapter 3: Working with Color in Applications

Working with color

Color reference pages 3-2

Ofﬁce applications

Choosing colors in ofﬁce applications 3-3 Resident calibration 3-3

2-1

2-4

2-6

2-11

3-1

3-2

PostScript applications

Choosing colors in PostScript applications 3-4 Resident calibration 3-6 CMYK simulation 3-6

3-4

ix Contents

Chapter 4: Printer Drivers and Print Options

What a printer driver does Adobe PostScript Printer Driver for Mac OS

Setting color management print options 4-2

Adobe PostScript Printer Driver for Windows 95

Setting color management print options 4-5

Adobe PostScript Printer Driver for Windows 3.1x

Setting color management print options 4-7

Microsoft PostScript Printer Driver for Windows NT 4.0

Chapter 5: Adobe Photoshop 4.0

Before you begin

With Windows versions of Photoshop 5-1 With Photoshop 2.5 for Mac OS 5-2

Deﬁning colors Saving ﬁles for importing into other documents Selecting options when printing

Printing RGB images 5-4 Printing CMYK images 5-5

4-1 4-2

4-5

4-6

4-8

5-1

5-2 5-2 5-3

Chapter 6: Page Layout Applications

Working with page layout applications

Deﬁning colors 6-1 Importing images 6-1 CMYK simulation and calibration 6-2

Adobe PageMaker 6.5 for Mac OS and Windows

Importing images 6-3 Selecting options when printing 6-4

QuarkXPress 4.02 for Mac OS and Windows

Importing images 6-8 Selecting options when printing 6-8

6-1

6-3

6-8

x Contents

QuarkXPress 3.32 for Mac OS and Windows

Importing images 6-12 Selecting options when printing 6-12

Chapter 7: Illustration Applications

Working with illustration applications

Deﬁning colors 7-1 Importing images 7-2 CMYK simulation 7-3

Adobe Illustrator 7.0 for Mac OS and Windows

Deﬁning colors 7-3 Importing images 7-5 Selecting options when printing 7-5 Saving ﬁles for importing into other documents 7-6 For advanced users: Using Illustrator color management 7-7

Macromedia FreeHand 7.0 for Mac OS and Windows

Deﬁning colors 7-8 Importing images 7-8 Selecting options when printing 7-9 Saving ﬁles for importing into other documents 7-10 For advanced users: Using FreeHand color management 7-11

6-12

7-1

7-3

7-8

CorelDRAW 7.0 for Windows

Deﬁning colors 7-12 Importing images 7-13 Selecting options when printing 7-13 Saving ﬁles for importing into other documents 7-14 For advanced users: Using CorelDRAW color management 7-14

7-12

xi Contents

Chapter 8: Ofﬁce Applications

Working with ofﬁce applications

Deﬁning colors 8-1 Working with imported ﬁles 8-1 Selecting options when printing 8-2 Calibration targets 8-2

Microsoft Ofﬁce 97

8-1

8-3

Glossary

Bibliography

Index

xiii About this manual

Introduction

Welcome to the associated with printing to a DocuColor 40 CP Color ServerTM. It also contains application notes that explain how to print to the DocuColor 40 CP from popular Windows and Mac OS applications.

This manual is one book in a set of documentation that also includes manuals for users and system administrators. All the other manuals should be available at your site— refer to them for a complete description of your documentation.

Color Guide

. This manual introduces you to the concepts and issues

About this manual

This manual is written for anyone who prints to a DocuColor 40 CP using popular Windows and Mac OS applications. It goes beyond the mechanics of sending a print job and explains issues that affect the quality of the results, such as:

• Use of color in the document

• Resolution and ﬁle formats used for imported images

• Features of ColorWiseTM color management performed by the DocuColor 40 CP

• Effects of print option settings on printed color Because each application has different options that affect color printing, detailed appli-

cation notes are included. Words in bold (for example,

Glossary. The Bibliography at the end of this manual provides sources for further investigation of color printing issues.

additive color model

), are terms that appear in the

The phrase “DocuColor 40 CP color management” refers to the ColorWise color management system built into the DocuColor 40 CP Color Server.

xiv Introduction

Tips for success

The built-in ColorWise color management system of the DocuColor 40 CP ensures that every color job you print looks good. Regardless of the computer you work on, the application you use, and the type of color work you do, your DocuColor 40 CP print device provides high-quality color output without any special effort on your part.

You can also customize the DocuColor 40 CP color management system for particular types of projects or environments. The DocuColor 40 CP provides total ﬂexibility, allowing you to specify color settings on a job-by-job basis.

The following list summarizes the issues you should consider when you create and print a color document.

1. Maintain and calibrate your print device and DocuColor 40 CP Color Server regularly.

(Chapter 2 and the

2. Use the Color Reference pages when choosing and deﬁning RGB and CMYK colors in applications. Use the PANTONE Reference pages when choosing PANTONE spot colors from within your application’s PANTONE library.

(Chapter 3)

Job Management Guide

)

3. Save raster images at the optimal resolution for your print device.

(Chapter 1)

4. Choose the appropriate settings for these print options (described in Chapter 2):

•

RGB Source

(and, for a custom RGB source space, Gamma, Phosphors, and White

Point)—affects the output of all RGB data in your document (see page 2-8)

Rendering Style

•

—determines the type of color effect produced; for example, vibrant colors (such as for presentations) or accurate-match colors (such as for spot colors in logos)

Brightness

•

CMYK Simulation

—increases or decreases the brightness of all colors in the document

—lets you use your DocuColor 40 CP print device as a prooﬁng

device for offset press jobs

CMYK Simulation Method

•

—determines the method of simulation used (quick or full)

1-1 The properties of color

Chapter 1: Desktop Color Primer

This chapter covers concepts that are basic to printing in color, including:

• The properties of color

• Printing techniques

• Using color effectively

• Raster images and vector images

• Optimizing ﬁles for processing and printing

• Workﬂow scenarios

If you are already familiar with color theory and digital color printing, you can skip to the last section (page 1-10) for tips on optimizing your ﬁles for printing.

The properties of color

What we call “color” is really a perceptual ability unique to humans and a small number of animal species. Color theory is an attempt to systematize the properties of color perception, which by nature is relative and changeable. A color appears different depending on the other colors around it, and individuals vary in their abilities to perceive color.

This section introduces concepts that are basic to color theory. You will encounter some of these concepts (such as hue, saturation, and brightness) when you work with color in applications; others provide useful background information.

topic, so consider this a starting point for experimentation and further research.

Color is a complex

The physics of color

The human eye can see electromagnetic radiation at wavelengths between 400 nanometers (purplish blue) and 700 nanometers (red). This range is called the visible spectrum of light. We see pure Sunlight at midday, which we perceive as white or neutral light, is composed of light from across the visible spectrum in more or less equal proportions. Shining sunlight through a prism separates it into its spectral components, resulting in the familiar rainbow of colors (plate 1).

spectral light

as intensely saturated or pure colors.

1-2 Desktop Color Primer

Like the sun, most light sources we encounter in our daily environment emit a mixture of many light wavelengths, although the particular distribution of wavelengths can vary considerably. Light from a tungsten light bulb, for example, contains much less blue light than sunlight. Tungsten light appears white to the human eye which, up to a point, can adjust to the different light sources. However, color objects appear different under tungsten light than they do under sunlight because of the different spectral makeup of the two light sources.

The mixture of light wavelengths emitted by a light source is reﬂected selectively by different objects. Different mixtures of reﬂected light appear as different colors. Some of these mixtures appear as relatively saturated colors, but most appear to us as grays or impure hues of a color.

CIE color model

In the 1930s, the Commission Internationale de l’Eclairage (CIE) deﬁned a standard

color space

communication of color information. This color space is based on research on the nature of color perception. The CIE chromaticity diagram (plate 2) is a twodimensional model of color vision. The arc around the top of the horseshoe encompasses the pure, or spectral, colors from blue-violet to red. Although the CIE chromaticity diagram is not perceptually uniform—some areas of the diagram seem to compress color differences relative to others—it is a good tool for illustrating some interesting aspects of color vision.

, a way of deﬁning colors in mathematical terms, to help in the

By mixing any two spectral colors in different proportions, we can create all the colors found on the straight line drawn between them in the diagram. It is possible to create the same gray by mixing blue-green and red light or by mixing yellow-green and blueviolet light. This is possible because of a phenomenon peculiar to color vision called

metamerism

different combinations of spectral light can produce the same perceived color.

Purple colors, which do not exist in the spectrum of pure light, are found at the bottom of the diagram. Purples are mixtures of red and blue light—the opposite ends of the spectrum.

. The eye does not distinguish individual wavelengths of light. Therefore,

1-3 The properties of color

Hue, saturation, and brightness

A color can be described in terms of three varying characteristics:

• Hue—tint (the qualitative aspect of a color—red, green, or orange)

• Saturation—the purity of the color

• Brightness—relative position between white and black.

While the CIE chromaticity diagram (plate 2) conveys hue and saturation, a threedimensional color model is required to add the brightness component (plate 3).

Many computer applications include dialog boxes in which you choose colors by manipulating hue, saturation, and brightness. For example, Photoshop uses a square Color Picker (plate 4) which can be reconﬁgured according to your preference.

Additive and subtractive color systems

Color devices used in desktop publishing and printing colors using a set of primary colors that are combined to create other colors. There ar e two methods of creating a range of colors from a set of primary colors. Computer monitors and scanners use the additive color model. Printing technologies, including DocuColor 40 CP print devices and offset presses, use the

simulate

the range of visible

subtractive color model

Additive (RGB) color

Color devices that use the additive color model make a range of colors by combining varying amounts of red, green, and blue light. These colors are called the

primaries

and blue light available. Black occurs wherever all three colors are absent. Grays are created by adding varying amounts of all three colors together. Combining varying amounts of any two of the additive primaries creates a third, saturated hue.

A familiar device that uses this color model is the computer monitor (plate 6). Monitors have red, green, and blue display a given color. Scanners create digital representations of colors by measuring their red, green, and blue components through colored ﬁlters.

(plate 5). White is created by adding the maximum amount of red, green,

phosphors

that emit varying amounts of light to

additive

1-4 Desktop Color Primer

Subtractive (CMY and CMYK) color

The subtractive color model is used in color printing, and in color photographic prints and transparencies. While the additive color model simulates the visible spectrum of color by adding light of three primary hues, the subtractive color model uses a “white ” or neutral light source containing light of many wavelengths. Inks, toners, or other

colorants

otherwise would be reﬂected or transmitted by the media in question.

The blue light, respectively (plate 7). Combining any two subtractive primaries creates a new color that is relatively pure or saturated. For example, you can make red by combining magenta and yellow, which absorb green and blue light, respectively. White occurs when no colorant is applied. Combining all three subtractive primaries in theory yields black, but due to deﬁciencies of cyan, magenta, and yellow colorants, combining these three primaries actually yields a muddy brown. Black colorant is added to compensate for the deﬁciencies of cyan, magenta, and yellow colorants, and consequently color printing uses four blacK (CMYK). The use of black ink helps in producing rich solid blacks and also allows for improved rendition of black text.

are used to selectively absorb (subtract) certain wavelengths of light that

subtractive primaries

are cyan, magenta, and yellow; they absorb red, green, and

process colors: C

yan, Magenta, Yellow, and

The CMYK colorants used in offset printing and by your DocuColor 40 CP print device are to some degree transparent. When one layer of colorant is applied on top of another, you see the effect of both. To create a range of intermediary colors, a method is required for varying the amount of each colorant that is applied. A technique called

halftoning

proprietary system for applying ink or toner colors that is similar to halftoning.

is used in offset printing, while color print devices typically use a

Printing techniques

Until recently, most color printing was done on printing presses using one of several printing techniques— All traditional printing techniques require lengthy preparation before a print run can take place. Short-run color printing, including DocuColor 40 CP printing, eliminates most of this preparation. By streamlining the process of color printing, the DocuColor 40 CP makes short print runs economically feasible.

offset lithography, ﬂexography

, and

gravure

, to name a few.

1-5 Printing techniques

In contemporary offset lithographic printing, digital ﬁles from desktop computers are output to an imagesetter, which creates ﬁlm separations. The ﬁlm is used to make a

prepress proof

opportunity to make corrections before going to press. Once the proof is approved, the printer makes plates from the ﬁlm and runs the print job on the press.

, which is an accurate predictor of the ﬁnal print job, allowing an

computer

Desktop computer

With a DocuColor 40 CP, you simply print the ﬁle. The DocuColor 40 CP processes the

PostScript

magenta, yellow, and black) to the print engine. The ease of DocuColor 40 CP printing makes possible experimentation that would be too costly on press, allowing unlimited ﬁne-tuning of color and design elements.

Halftone and continuous tone devices

Halftoning is used in offset printing to print each process color at a different intensity, allowing millions of different colors to be reproduced using only the four process colors. Depending on the required intensity of a given color, ink is placed on paper in dots of different size. The grid of dots used for each ink color is called a screen. Halftone screens are aligned to unique angles designed to eliminate interference patterns called

Imagesetter Film Proof PressDesktop Print run

Print device Color prints

information in the ﬁle and sends four

moiré

that can arise with halftoning.

bitmaps

(one each for cyan,

1-6 Desktop Color Primer

Some color print devices are commonly referred to as devices. They do not use traditional halftone screen patterns and angles. H owever, they do apply dots (in some cases very elongated dots or lines) of different sizes to paper in a process similar to halftoning.

Some DocuColor 40 CP systems have an optional Halftone Printer mode. When this option is selected, the DocuColor 40 CP sends data to the print device as though it were a halftone device, with each device pixel assigned either the maximum amount of toner, or none at all. The halftone option, however, does not use the type of halftone screens used in offset printing, nor does it duplicate results obtained in offset printing.

Even if your color printing is done exclusively on the DocuColor 40 CP, you will encounter concepts from offset printing if you use high-end graphics applications. For example, color controls in illustration applications such as Illustrator are geared toward specifying color for offset printing using process and allow you to specify the screening used for each printing plate.

continuous tone

spot colors

. Many applications

(or “contone”)

Using color effectively

The ability to print in color can greatly increase the effectiveness of your message, whether you are printing a presentation or a newsletter , or pr ooﬁng an ad concept that will later be printed on press. Some potential beneﬁts of using color include:

• Conveying information rapidly by using color cues

• Making use of the emotive aspects of different colors

• Increasing impact and message retention

Color can also be a source of distraction and discord if it is used poorly. This section outlines some tips and concepts that will prove useful as you approach designing color materials.

1-7 Using color effectively

A few rules of thumb

Try some of the following strategies for creating successful color materials:

• Rather than applying colors indiscriminately, use color to aid comprehension. In presentations, graphs, and charts, use color to highlight patterns and emphasize differences.

• In general, fewer colors work better than many colors.

• Use red as an accent color. Red is particularly effective when used in otherwise monochromatic materials.

• Consider the tastes of your target audience when choosing colors.

• Keep a ﬁle of printed color pieces that appeal to you or strike you as effective. Refer to it for ideas when designing your own documents.

Color wheel

A color wheel (plate 8) is a helpful tool for understanding the interrelation of colors. The colors on one side of the color wheel, from magenta to yellow, appear to most people to be warm colors, while those on the other side, from green to blue, appear to be cool. The distance between two colors on the color wheel can help predict ho w they will appear when seen side by side.

Colors opposite one another on the wheel are called complements (plate 9), and create a striking contrast side by side. This can be the basis for a bold graphical design, but it is an effect you should use with discretion since it can be visually fatiguing. Other bold combinations to consider are split complements (a color and the two colors adjacent to its complement) and triads (three colors evenly spaced on the color wheel). Colors adjacent to one another on the color wheel result in subtle harmonies.

The color wheel simpliﬁes color relationships for the purpose of clarity, showing only saturated or pure colors. Adding the myriad variations of each hue to the palette (more or less saturated, darker or lighter) creates a wealth of possibilities. Taking a pair of complements from the color wheel and varying the saturation and brightness of one or both colors produces a very different result from the pure complements. Combining a light tint of a warm color with a darker shade of its cooler complement often gives pleasing results. Combining a darker shade of a warm color with a light tint of its cooler complement produces an unusual effect you may like.

1-8 Desktop Color Primer

Once you have mastered the concept of the color wheel, you have a good framework for experimenting with color combinations. Many books targeted at graphic designers show groups of preselected color combinations. Some are organized by themes or moods, and some are based on a custom color system such as PANTONE. The more you develop a critical facility for judging color combinations, the more you will be able to trust your own eye for color. The Bibliography at the back of this manual includes books on design.

Color and text

It is not a coincidence that the overwhelming majority of text you see is printed in black on white paper. Text in black on white is highly legible and is not fatiguing to read for extended periods. For many color materials, using black text on a white background and conﬁning color to graphic elements and headings is a good choice.

Color text can add ﬂair to documents printed on paper when used skillfully, and is widely used in presentations. When using color text, avoid dazzling text and background combinations created from primary complements, especially red and cyan or red and blue; they are visually fatiguing and hard to read. Color text is more legible when distinguished from its background by a difference in lightness—for example, dark blue text on a light beige background. In addition, using many different colors in a string of text makes for a confused appearance and is hard to read. However, using a single highlight color is an effective way to draw the reader’s eye to selected words. See plate 10 for color text samples.

When using color text, keep in mind that small font sizes typically do not print in color with the same sharpness as in black. In most applications, black text prints exclusively in black toner, while color text usually prints with two or more toners. Any misregistration between the different toners on paper causes color text to lose deﬁnition. You can make test prints to ﬁnd the smallest point size at which color text prints clearly. When using high-end graphics applications that allow you to specify color as percentages of cyan, magenta, yellow, and black, you can create pure cyan or pure magenta text that prints with the same sharpness as black text. (Pure yello w text is extremely hard to read on anything but a dark or complementary background.)

1-9 Raster images and vector images

Registration and trapping

With any print device, there is the possibility that the different toners may print slightly out of register, producing distracting gaps between objects. Trapping is the process of spreading one color slightly into adjacent colors to compensate for any misregistration that might occur when the ﬁle is printed. Depending on the job’s makeup, you may need to take trapping into consideration for best printed results. See the Bibliography for sources of information on trapping.

The DocuColor 40 CP includes a Combine Separations print option. This option can be used with PageMaker and QuarkXPress to proof trapping, overprinting, and other four-color printing effects before creating ﬁlm separations. With Combine Separations turned on, separations are printed in color on a single page. The Combine Separations print option also enables you to combine Desktop Color Separations (DCS) ﬁles to print at high resolution instead of printing the low-resolution master ﬁle. For more information, see the Printing Guide.

Raster images and vector images

Two broad categories of artwork can be printed from a personal computer to a color printer: raster and vector images (plate 11).

A raster image, also referred to as a bitmap, is composed of a grid of pixels, each assigned a particular color value. The grid, when sufﬁciently enlarged, resembles a mosaic made from square tiles. Examples of raster images include scans and images created in painting or pixel-editing applications, such as Photoshop and Painter.

The amount of information found in a raster depends on its resolution and bit depth. The resolution of a raster describes the density of the pixels and is speciﬁed in pixels per inch (ppi). The bit depth is the number of bits of information assigned to each pixel. Black and white rasters require only one bit of information per pixel. For photographic quality color, 24 bits of RGB color information are required per pixel, yielding 256 separate levels of red, green, and blue. For CMYK images, 32 bits per pixel are required.

When printing raster artwork, the quality of the output depends on the resolution of the raster. If the raster’s resolution is too low, individual pixels become visible in the printed output as small squares. This effect is sometimes called “pixelation.”

1-10 Desktop Color Primer

In vector images, picture elements are deﬁned mathematically as lines or curves between points—hence the term “vector.” Picture elements can have solid, gradient, or patterned color ﬁlls. Vector artwork is created in illustration and drawing applications such as Illustrator and CorelDRAW. Page layout applications such as QuarkXPress also allow you to create simple vector artwork with their drawing tools. PostScript fonts are vector-based as well.

V ector artwork is r esolution-independent; it can be scaled to any size without danger of pixels becoming visible in printed output.

Optimizing ﬁles for processing and printing

The following sections provide tips on how to create image ﬁles that produce the highest possible print quality while minimizing the processing time and disk space they require.

Resolution of raster images

While a 72 ppi raster image appears sharp on a monitor, the same image would likely appear pixelated when printed to the DocuColor 40 CP. Color print devices are capable of much greater detail than monitors, and require correspondingly higher resolution image ﬁles. However, high-resolution ﬁles can be large, and therefore cumbersome to transmit over a network, process for printing, store on disk, and edit.

Beyond a certain threshold, a higher image resolution greatly increases ﬁle size while having a minimal effect on output quality. The optimal image resolution depends on the resolution of the ﬁnal print device. Aim for the resolution that optimizes both ﬁle size and output quality.

1-11 Optimizing ﬁles for processing and printing

The resolution of a raster image, along with its bit depth and physical dimensions, determine its ﬁle size. The following table shows the ﬁle sizes of color raster images at different dimensions and resolutions.

File size at:

Image size 100 ppi 150 ppi 200 ppi 400 ppi

RGB/CMYK RGB/CMYK RGB/CMYK RGB/CMYK

x 4" x 7"

x 11"

8.5"

x 17"

11"

In this table, the shaded areas indicate that 200 ppi is typically the best trade-off between image quality and ﬁle size. However, higher resolutions (e.g., 250 to 300 ppi) may be needed for offset printing, when quality is of the utmost importance, or for images containing sharp diagonal lines.

To ﬁnd the best image resolution for your purposes, make test prints of some raster artwork at different resolutions. Start with a high-resolution image (400 ppi) and save versions at progressively lower resolutions, down to 100 ppi, using a pixel-editing application such as Photoshop. Always save a copy of the original high-resolution version in case you need to revert to it. The high-resolution data cannot be recreated from a lower resolution version.

0.4/0.5 MB 0.8/1.0 MB 1.4/1.8 MB 5.5/7.3 MB

1.0/1.3 MB 2.3/3.0 MB 4.0/5.3 MB 16.0/21.4 MB

2.7/3.6 MB 6.0/8.0 MB 10.7/14.3 MB 42.8/57.1 MB

5.4/7.1 MB 12.0/16.1 MB 21.4/28.5 MB 85.6/114.1 MB

Image quality

1-12 Desktop Color Primer

Print the ﬁles and examine the output. You will likely begin to see a marked deterioration in output quality at resolutions below 200 ppi, while above 200 ppi the improvement may be very subtle.

100 ppi 200 ppi 300 ppi 400 ppi

Image resolution

Raster images prepared for offset printing may need to be at higher resolutions than needed for prooﬁng on your DocuColor 40 CP. Check with your prepress service provider and printing vendor for their recommendations on image resolution based on your job speciﬁcations.

Scaling

Ideally, each raster image should be saved at the actual size it will be placed into the document and at the optimal resolution for the print device. If the image resolution is correct for the print device, there is no quality advantage to be gained by scaling an image down to a percentage of its actual size. If you scale a large image down to a percentage of its actual size, you incur unnecessary ﬁle transfer time because the image data for the entire large image is sent to the printer . If an image is placed multiple times at a markedly different sizes in a document, save a separate version of the image at the correct size for each placement.

If you need to place an image at greater than 100% in a document, remember that the output image resolution is affected. For example, if you scale a 200 ppi image to 200%, the image is printed at 100 ppi.

1-13 Workﬂow scenarios

Workﬂow scenarios

Color print jobs can be divided into two categories:

• Short-run print jobs for which the DocuColor 40 CP is the ﬁnal print device

• Offset print jobs being proofed on the DocuColor 40 CP

For either type of job, issues of effective color usage, trapping, ﬁle optimization, and scaling are important ones. The areas of differ ence between the workﬂows for these two types of jobs are outlined in the following sections.

Short-run color printing

For short-run color jobs printed to the DocuColor 40 CP:

• You can work in either the RGB color model or the CMYK color model (see the application notes). When working with RGB colors, you should take advantage of the color rendering capabilities of the DocuColor 40 CP (see Chapter 2).

• When choosing or deﬁning colors in your application, use the DocuColor 40 CP color reference pages to be assured of predictable results (see Chapter 3).

• When printing, choose the appropriate settings for print options that affect color output (see Chapter 2).

• When printing, make sure the resident calibration on the DocuColor 40 CP is the appropriate one for your job. The DocuColor 40 CP includes a calibration target designed for your print device, but you can also create a custom target to achieve particular color effects (see Chapter 2 and the Job Management Guide, which describes DocuColor 40 CP calibration).

1-14 Desktop Color Primer

Offset printing

For jobs that will be proofed on the DocuColor 40 CP in preparation for being printed on an offset press:

• Work in the CMYK color model only (see the application notes). All elements in your document, including placed images, must be in the CMYK color model to create ﬁlm separations for printing.

• When choosing or deﬁning colors in your application, use the DocuColor 40 CP color reference pages to be assured of predictable results (see Chapter 3).

• If cost is a factor and the document does not contain CMYK images, consider using two or three PANTONE colors, instead of the standard four process colors (see Chapter 3). This reduces the number of ﬁlm separations and printing plates needed to print the job.

• If your document contains high-resolution CMYK raster images, you can reduce processing time by saving the images in Encapsulated PostScript (EPS) format with Photoshop using Desktop Color Separations (DCS). A DCS image consists of ﬁve separate ﬁles—one for each of the CMYK color channels of the image, plus one lowresolution master composite ﬁle that you use for placement in the document (see your Photoshop documentation). The low-resolution master ﬁle provides a composite preview of the image for screen viewing and is used to print composites. DCS ﬁles do not use less disk space than single CMYK ﬁles, but they do reduce the amount of time needed to send image data to the printer. DCS ﬁles can be used to create ﬁlm separations as well.

• Use the Combine Separations print option to check for trapping problems (see the Printing Guide).

• Choose the appropriate CMYK Simulation and CMYK Simulation Method settings (see Chapter 2).

2-1 Controlling printed color

Chapter 2: Color Management

This chapter provides information on the factors involved in controlling and managing color output with the objective of achieving predictable color results, including:

• Controlling printed color

• Basics of color management

• DocuColor 40 CP color management

• Optional ICC color management on Mac OS and Windows computers

Controlling printed color

When working with color materials, whether they be presentations, illustrations, or complicated page designs, you make aesthetic decisions about the colors you use. Once you have decided on your goal, you then need to realize it in print. Your color printing system becomes an ally in this creative process to the extent that you can get results that are predictable.

• If you have designed a brochure to print on the DocuColor 40 CP, you want the printed colors to match the design speciﬁcation.

• If you are printing presentations on the DocuColor 40 CP, you want to preserve the vivid colors in the monitor display.

• If you are working with color that will print on press, you want the DocuColor 40 CP output to match prepress proofs or PANTONE color swatch books.

The type of print job and the ﬁnal print device, DocuColor 40 CP or offset press, determine the methodology you use to achieve optimal results.

No matter what your goals are, two hardwar e factors always impact color print output: print device consistency and the range of colors the print device can print, known as its gamut. These factors are covered brieﬂy in this chapter. Creating successful color documents and presentations also requires an understanding of color management software as it is implemented by the DocuColor 40 CP and on your desktop computer. Most of this chapter is devoted to discussing the various elements of color management that contribute to predictable color results.

2-2 Color Management

Maintaining print device consistency

The factors described below affect print device consistency, as well as color ﬁdelity and overall output quality.

Paper stock and toner

The paper and toner used by your print device can greatly affect printed color . F or best results, use the supplies recommended by the manufacturer of the print device.

Maintenance

Problems such as streaking and insufﬁcient or excessive amounts of one or mor e toners arise when a print device does not receive periodic maintenance or needs major repairs. In addition to having it serviced regularly, monitor the condition of your print device by making standard test prints at regular intervals. You can do this easily by printing the DocuColor 40 CP Test Page. Save the prints and show them to the service technician whenever output densities vary from the norm or other problems appear.

Calibration

Output from color print devices is subject to changes in temperature and humidity, and is prone to drift over time, with a resulting loss in color predictability. For this reason, regular service visits alone do not guarantee consistent results from a print device. Where color accuracy and consistency are crucial, regular calibration of the DocuColor 40 CP and print device is necessary.

Calibration compares the measured toner densities from a color print device to a set of target densities and downloads a software correction to the DocuColor 40 CP that keeps the densities consistent. Calibration also optimizes the DocuColor 40 CP’s color response for use with the DocuColor 40 CP color management system (see page 2-6).

A resident calibration target is speciﬁed during DocuColor 40 CP calibration. The administrator or operator can create custom calibration targets as needed for the speciﬁc requirements of your site. For information on performing calibration, see the Job Management Guide, which describes DocuColor 40 CP calibration.

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