Color Separation. GLOBAL GRAPHICS SOFTWARE Navigator RIP version 8.1

13

Color Separation

This chapter describes some basic concepts of color reproduction and the related parts of the Navigator RIP.

The concept of color separation is no longer restricted to producing separated output. When processing any job, the RIP creates a separation for each process colorant and also, where appropriate, for spot colorants. The output format determines whether the separations are printed together as a composite, or separated. By configuring these separations you can control the printing of individual colorants in the job. Although there is only one separation in the monochrome color space, the RIP provides the same options for configuring that separation.

Separations information is saved together with screening information in a separations style, which can be used in several Page Setups. A separations style is defined for a specific device, color space, and output format. Selecting a separations style in the Edit Page Setup dialog box determines the color space of the Page Setup.

These are the related parts of the Navigator RIP:

•

The Separations Manager and Edit Style dialog box. See “Creating and managing separations”

on page 348 for details of the choices you make for all separations. (See Chapter 6, “Screening” for details of the screening options for halftone separations.)

•

The Color Setup dialog box. See “Color Setup” on page 358. This dialog box contains the con-

trols for black generation and undercolor removal, trapping, and overprinting.

•

Use of the Output Controller to view superimposed color separations. See “Pages in the Output

Controller” on page 370. The Output Controller is available in either of the multiple modes.

This chapter describes how you can define separations styles, while Chapter 5, “Configuring Output

Formats”, describes how you can choose different separations styles when producing output.

13.1 Introduction

To produce a color image, many reproduction systems take advantage of the fact that there are small sets of colors that, when mixed in the correct proportions, can produce any of a very wide range of other colors. For example, combinations of red, green, and blue inks (commonly known as RGB), or cyan, magenta, and yellow inks (CMY), can between them produce thousands of different hues.

Color printing more commonly uses CMY colors, with the addition of a black ink to account for imperfections in the printing process. This manual uses the term CMYK for the system of color repre-

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sentation using these four inks (Cyan, Magenta, Yellow, and blacK). These inks are the commonly used process colors. There are several other terms in common use, some terms using B for Black or referring to the order of printing each ink by reordering the letters: YMCK, YMCB, and KCMY are typical.

Black ink is used for several practical, economic, and quality reasons:

• Black appears very often: for example, in text.

• Black ink is cheaper than colored inks.

• Mixing CMY inks produces an impure black, probably tinged with brown, and can result in objectionable colored fringes on small objects such as characters in body text. Additionally, one application of black ink replaces three applications of colored inks so drying time can be reduced.

• Black can be used to extend the range of colors and tints available from mixing CMY inks.

There are ways to improve reproduction quality or economy beyond the levels possible with CMYK process inks. There are two general approaches: to vary the number of process inks (HiFi or N-color printing), or to add spot colors. Each approach has its own advantages.

13.1.1 Alternative process color systems

N-color printing uses a different number of process colors: fewer for economy in simple jobs such as forms printing or more for high quality. For high-quality printing, or HiFi color, at least two distinct types of color schemes are growing in popularity: for convenience in this discussion we shall call them distinct colorant and photo-ink.

Distinct colorant printing uses a combination of different process colors. For example, in the PAN-

TONE Hexachrome Color Selector system there are six inks: cyan, magenta, yellow, black, orange, and green. (Other schemes of six or seven distinct colors are possible but this system is well known.)

These colors are chosen as a set to provide a wider gamut than provided by colorants in the established

CMY or CMYK schemes so, for example, the cyan in a six-color system is unlikely to be the same as the cyan in a typical CMYK system. To avoid confusion a different naming scheme is needed. There is not a single fixed set of names: HexC or HexCyan are equally valid names for the cyan ink and may be used by graphics applications creating jobs.

Photo-ink technologies use a different approach. There are different densities (light and dark versions) of one or more colorants. A capable system is then able to use the light ink in highlight areas and the dark ink where more colorant is required. A typical set of colors is light cyan, dark cyan, light magenta, dark magenta, yellow, and black. As in distinct colorant systems, these are not the same inks as used in the CMYK system and it is important to distinguish between the two systems. Various naming schemes are possible: a possible example is PhotoCyan Light, PhotoCyan, PhotoMagenta Light,

PhotoMagenta, PhotoYellow, and PhotoBlack.

The Navigator RIP provides facilities for screening and calibrating both of these color systems, but the actual availability for use of a distinct colorant or photo-ink color space depends upon there being an installed output plugin using the new software facilities. Also, some configuration of the files in which the RIP stores colorant databases may be needed before first use. For example, the Navigator RIP allows for jobs to use any of the different color naming schemes discussed for distinct colorant and

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13.1 Introduction

photo-ink systems and to link these to the internal naming scheme used by the RIP. Each new naming scheme requires some configuration.

13.1.2 Spot colors

Spot colors are used in a job when a particular color is used very heavily or must have a better quality than is available by mixing the process colors. Typical uses of spot color include colored text, company logos, and colors that are outside the range available from mixing process colors. Spot colors may also be used to define effects other than coloring: for example, to place varnishes and glues.

13.1.2.1 The PANTONE MATCHING SYSTEM

®

The Navigator RIP is able to make use of the PANTONE MATCHING SYSTEM. Colors are identified as M (matte), C (coated) and U (uncoated). For example,

PANTONE 533 M

,

PANTONE 533 C

, and

PANTONE 533 U

. Previously, Pantone colors were identified as CV (coated) and CVU

(uncoated). For example

PANTONE 533 CV

and

PANTONE 533 CVU

.

From v8.0 The Navigator RIP is able to make use of the PANTONE

®

Goe

™

coated color system.

From v8.1 The Navigator RIP is able to make use of the PANTONE

®

Goe

™

uncoated color system.

All the Pantone Databases can be found in

SW\NamedColor

.

To use the PANTONE MATCHING SYSTEM the color names must match exactly the names used in

the job. For information on how to include color separations see “Producing separations” on page 353.

As previously stated, all the Pantone Databases are in

SW\NamedColor

.

The

PantoneProcess database is found in the

SW\NamedColor\Examples

folder. To make this database work, it must be referenced in one of the files in

SW\NamedColorOrder

. You do this by editing the

Intercept

,

Recombine

and

Roam

files. If you want to produce all Pantone colors by their CMYK equivalents, put

PantoneProcess

before

PantoneU

in the files. Putting

PantoneProcess at the end of the file (that is, after

PantoneMatte

) will mean only the PC Pantone colors will be found (that is,

PantoneU

and

PantoneV

colors will still be converted to XYZ).

13.1.3 Types of color jobs

There are two common types of color jobs:

• All the color information is in one job. This is a full-color job, also known as a color composite.

• The color information has been separated into a page for each color ink. This is a preseparated

job. These pages may be parts of one job or separate jobs.

Composite jobs offer the greatest flexibility in handling jobs and targeting them to different output devices, but many workflows are built around preseparated jobs. The RIP can recombine many pre-

separated jobs, provided that the separations are supplied as one job. (“Color PostScript language jobs” on page 347 and “Preseparated jobs” on page 347 describe the details of using composite and

preseparated jobs with the RIP.)

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13.1.4 Navigator RIP

This chapter describes how you can produce output from documents for use in CMYK color printing.

You can also produce output for other color systems, such as RGB and N-color, and output for jobs that include spot colors. The Navigator RIP accepts either full-color jobs or preseparated jobs as input, and outputs them correctly.

The Navigator RIP also provides some extensions to the PostScript language specification: for example, the ability to recognize spot colors in documents defined using the PostScript Level 1 language.

13.1.5 ColorPro

ColorPro extends the color handling capabilities of the RIP. For example, you can use ColorPro to intercept CMYK color definitions and convert them to device-independent color using input profiles.

The extra facilities and changes of procedure associated with ColorPro are described in the separate manual ColorPro User’s Guide.

13.2 What color separations are

Color printing using this color-mixing method is done using color separations. These are sets of sin-

gle-color images that yield a full-color image when combined appropriately. Figure 13.1 shows how

four single-color images can be combined to produce an image in different colors. In this grayscale figure, different shades of gray represent the various colors.

Cyan

Separations produced in four process colors

Magenta Yellow Black

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Overlay process yields full color images

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Manual

Figure 13.1 How separations can form a color image

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13.2 What color separations are

The image in the figure shows the cover page of a fictional magazine. It is mostly black, but has a small color illustration on the right that consists of some land (in green), over which there is a road (in pure black), and in the sky (not colored) the sun (in pure yellow) is shining.

Color images are not produced from separations by mixing inks before application to the page.

Instead, the illusion of a full-color image is produced by seeing different proportions of the four inks laid together on the page. Each separation adds one color component to the image—cyan, magenta, yellow, and black in turn—and, when they are overlaid correctly, they form a full-color image.

A color separation is, strictly speaking, a monochrome (that is, one color) image. It is called a color

separation because it is the result of separating one color from the others in the color system. For example, the yellow separation in CMYK is a version of the image that shows only the yellow part of it, separated from the cyan, magenta, and black. (You can control how colors will be separated from the others in an image.)

Seen in isolation, a single separation may not look much like the full-color image of which it will form

a part but it is usually possible to identify some features of the final image. In Figure 13.1, the yellow

separation shows the sun, which is pure yellow. It also shows a small amount of yellow in the ground part of the image, which will combine with the cyan separation to form the grass color. However, it does not contribute to the road or the text, and so it is empty in those places.

13.2.1 Knockouts and overprinting

Suppose we have a very simple image that is a pure magenta background with a pure yellow square in

the middle. The separations produced will be those in Figure 13.4.

Cyan

Separations for a yellow square on a magenta background

Magenta Yellow Black

Figure 13.2 Color separations for a simple image, with knockouts

Since the yellow and magenta inks can portray yellow and magenta quite adequately on their own, the cyan and black separations are empty.

The yellow separation shows a square in the middle and nothing else. The square signifies the presence of yellow in the image at that point. The magenta separation shows a white square on a magenta background. So, magenta will be printed in every part of the image except for that square.

Because magenta will not be printed in the white square, only yellow will appear there when the separations are put together. This is important, since if magenta was printed there too, it would mix with the yellow, and produce a square that was not pure yellow, but red. Equally, no other inks will overlap

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the magenta background, because no separations other than the magenta one contribute any color to that region.

An area of a separation that is made empty so that it does not interfere with a graphic object represented by a color or colors in other separations is called a knockout. This is because the colored area has been knocked out of the separation.

One problem with using knockouts is that if the separations are not overlaid accurately enough, there

may be a white gap at the edge, as shown in Figure 13.3. This effect is the product of misregistering

the separations, that is, misaligning them when they are combined. Nevertheless, in cases where printing one ink on top of another would produce the wrong color, producing separations with knockouts is essential. Generally, graphic and page design applications produce knockouts automatically.

Inaccuracies caused by misregistered knockouts can be overcome by using special printing effect such

as trapping. The RIP provides some support for trapping. See “Trapping features” on page 369.

Figure 13.3 Misregistered separations with white gaps

Suppose we have another simple image that is a pure magenta background with a black square in the

middle. Figure 13.4 shows the separations that can be produced.

Separations for a black square on a magenta background

Cyan Magenta Yellow Black

Figure 13.4 Color separations for a simple image, with black overprinting

In this case, we do not need to make a knockout on the magenta separation, because the black ink should be strong enough to overcome the influence of the magenta ink beneath it. So we may choose

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13.3 Producing color images from separations

not to let the black separation cause a knockout in the magenta separation. This effect is called over-

printing, and is the opposite of a knockout. Overprinting eliminates the risk of finding gaps in the final output, but cannot be used unless the overprinted ink is strong enough to overcome the effects of the ink or inks beneath it. When overprinting is not possible, trapping remains a possibility.

13.3 Producing color images from separations

In the RIP, depending on the output format, you can print separations together as a composite page, colored separations, or each separation as a monochrome page.

If you print a set of monochrome separations for use in the printing process, these separations can be put together to form a color image. The separations are carefully placed one on top of the other until all the color details can be seen. How is this achieved?

Typically, color pictures do not consist only of areas drawn in full-intensity primary colors. Most of the picture is usually be in various shades and tints. Most printing presses require screened halftones, so these varying intensities are achieved by using halftone dots. Each separation, therefore, is usually

composed of a pattern of halftone dots. (See Chapter 6, “Screening”, for details of halftoning.)

In halftoning strategies, continuous tone gray or colored images are imitated by combining dots of different sizes and colors. They are combined in such a way that, to the human eye, they mix, and the observer sees the intended color image.

To ensure that the colors combine correctly, the positions of the dots on each separation are calculated carefully. The grids, or halftone screens, for each separation are aligned at different angles, to avoid

moiré patterns.

Once each separation has been produced, the final image can be constructed by printing the separations directly on top of each other. The intermediate stages are progressive proofs. In the CMYK

model, this is usually done by printing yellow first, then magenta, cyan, and finally black. Figure 13.5

and the following figures show the stages involved when printing color in this way for the example

image in Figure 13.1, page 342.

Blank paper Yellow separation

Figure 13.5 Yellow separation

Yellow

Figure 13.5 shows how yellow ink for the yellow separation is printed on blank paper. You can also

preview separation printing on screen in the RIP. See “Roaming separations” on page 370.

Next, the magenta ink for the magenta separation would be printed on the paper, but since the separation is empty for this image, nothing is printed.

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Yellow Magenta separation Yellow + Magenta

Figure 13.6 Yellow and (empty) Magenta separations

Next, the cyan ink for the cyan separation is printed. To the eye, the pattern of cyan and yellow dots in

the area of land will appear green as simulated in Figure 13.7.

Yellow + Magenta Cyan separation Yellow + Magenta + Cyan

Figure 13.7 Yellow, Magenta, and Cyan separations

Finally, the black ink for the black (K) separation is printed. All of the separations have been com-

bined, producing a full-color image as simulated in Figure 13.8.

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Yellow + Magenta + Cyan Black (K) separation Full CMYK image

Figure 13.8 Yellow, Magenta, Cyan, and Black separations

13.4 How color separations are produced

Each job may specify color images in one or more different color spaces, for example: CMYK, RGB

(red, green, and blue), HSB (hue, saturation, brightness), or an N-color space. No matter how a job is specified, the RIP separates that job into one output format, to suit the output device. Again, in this discussion we will concentrate on CMYK separations as an example.

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13.4 How color separations are produced

13.4.1 Color PostScript language jobs

Composite color jobs are not described as a series of separations. Instead, each object on the page is described just once, in full color.

Importantly, the PostScript language method of describing color is device independent. That is, no matter what color space is used to describe an image, it can be rendered on any properly color-calibrated output device that your RIP supports. The same color job can thus be used to produce, for example, full-color output on an RGB color printer, or a set of monochrome separations ready to be used in the printing process. Some devices, typically desktop printers and proofing systems, can accept continuous tone input.

Note: If you have ColorPro available, you can apply it to CMYK separations as well as to color composite CMYK jobs. The separations must be suitable for use with the

Recombine preseparated jobs

option described on page 355.

The RIP can take full-color jobs as input, and interpret them once to produce separation information for each color in the space. In CMYK, this creates four monochrome output pages, each corresponding to a different color separation. When the full-color image is to be produced, the colored parts of a separation show where inks should be applied, and the white parts where not. Alternatively, the RIP can print the separations together as a composite.

13.4.2 Preseparated jobs

Having the RIP produce separations from composite color jobs is not the only means of producing separations. The job could be separated into one or more PostScript language documents before it reaches the RIP. This might be done by the application program in which the job was composed, or by a special separator program that took the output of the composition program and produced PostScript language separations from it.

However, these methods are not optimal. If you preseparate the job, you commit yourself to printing the job on a device that can recombine the separations it produced: the documents become device

dependent. A process that commits a job to a particular device is not desirable, because you may need to output your job on a number of different devices. The RIP can recombine certain classes of preseparated jobs: see the description of the

Recombine preseparated jobs

option on page 355 for details.

There some circumstances where you must use recombination with preseparated jobs in order to use features of the RIP, and some of these circumstances apply even when you wish to produce separations. These features are:

• Output to a composite proofing (or final output) device.

• Color management, using ColorPro.

• Trapping, with the in-built options in the RIP.

• Output to progressive separations.

• Output of separations in a different order.

All these features require the RIP to have access to the complete color of all objects on a page. To ensure that this is possible for preseparated jobs, select

Recombine preseparated jobs

. Alternatively, where other settings in the Page Setup prohibit recombination, select

Reject preseparated jobs

.

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Note: Both colored separations and progressive separations require the output color space to match that of the separations. For example, it is not possible to produce colored separations or progressive separations from a job preseparated to CMYK if the output device uses the PhotoInk color space.

The RIPs separation facilities allow you to preserve device independence in your jobs right up until you wish to interpret it for output on a particular device. However, you can present device-dependent, preseparated jobs to the RIP if you wish, and it will process and output them correctly.

13.5 Creating and managing separations

Separations information is saved together with screening information in a separations style, which can be used in several Page Setups. A separations style is defined for a specific device, color space, and output format. Selecting a separations style in the Edit Page Setup dialog box determines the color space of the Page Setup.

Separations styles are created and managed in the Separations Manager.

13.6 Separations Manager dialog box

The Separations Manager appears when you click the

Separations Manager

button in the Edit Page

Setup dialog box, or choose the

Color > Separations Manager

command.

Figure 13.9 Separations Manager dialog box

The Separations Manager displays a list of all existing separations styles for the current device, showing the name of each separations style, the corresponding color space, and the output format.

To display the list of separations styles for a different device, select a device name from the

Device

drop-down list. When you use a device for the first time, the RIP generates a set of separations styles for that device. Some devices can support simple styles only. Others, like TIFF, can produce many different styles, so the names of the styles are chosen to avoid ambiguity.

You can edit these separations styles to suit your installation or create new ones.

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13.6 Separations Manager dialog box

13.6.1 Controls and actions

The controls below the list allow you to create separations styles, and to edit, copy, or delete existing separations styles.

Edit

New

Copy

Select a separations style and click this button to edit it in the Edit Style dialog box. A shortcut is to double-click a separations style.

Note: To rename a separations style, copy it and save the copy with the desired name, before deleting the original.

Click this button to create a new separations style. The New Style dialog box

appears, as described in “New Style dialog box” on page 350.

Once you have set the color space and output format, you cannot change them for the named separations style.

Select a separations style and click this button to edit a copy. The New Style

dialog box appears, as described in “New Style dialog box” on page 350.

Delete

Select one or more separations styles and click this button to delete them together. You cannot delete a separations style if it is used in a Page Setup.

You cannot delete the only separations style in a list.

Select

This button is available if you opened the Separations Manager from the Edit

Page Setup dialog box and a separations style is selected.

The

Select

button confirms the changes you have made and exits the dialog box. In addition, the

Select

button displays the selected separations style in the Edit Page Setup dialog box.

You can also select separations styles and reorder them by dragging them to new positions in the list.

The order in the Separations Manager is the order of appearance in menus where you choose a separations style.

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13.6.2 New Style dialog box

The New Style dialog box appears when you click the

New

or

Copy

button in the Separations Manager.

Note: If you clicked

Copy

to display this dialog box, you can change only the style name: this ensures that the new style is a true copy of the original. Once you have named the copy and clicked

Create

, you can modify individual settings in the Edit Style dialog box.

Figure 13.10 New Style dialog box

Style name

Color space

Type in a name for the separations style. The style name must be unique and can be up to 30 characters long.

Select the color space from the drop-down list. You can select any color space known by the RIP, not just the color space of the target device. Monochrome, RGB, and CMYK are always available. If you have installed an Ncolor device, you can also use its color space, even if you are not printing to that N-color device. This choice determines the process colorants specified in the separations style. The output format specifies how the colorants will be printed on the output device.

Output format

Once you have selected the color space, select an output format from the drop-down list. This specifies how to generate the output on the target device.

The available options depend on the selected output device and the setting for

Color space

. For example, with a typical CMYK device operating in its own color space, you can generate output as monochrome separations, as colored separations (either single or progressive proofs), or as a composite. For an

RGB output device, you can convert CMYK or N-color separations to RGB output, and so on. When an arrow appears in the output format name, it indicates that the color space does not match that of the output device.

Note: Once you have set the color space and output format, you cannot change them for the named separations style.

Click the

Create

button to open the Edit Style dialog box, described in “Edit Style dialog box” on page

351. Click

Cancel

to discard your changes immediately.

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13.7 Edit Style dialog box

13.6.3 Selecting several separations styles

You can select multiple separations styles when you want to delete or reorder them. Use the following keys:

Shift

To select a block of separations styles that appear together in the list, select the first style in the block, then, while holding down the Shift key, select the last style in the block.

Ctrl

To select several separations styles, regardless of whether they form a continuous range, hold down the Control key while selecting the styles you wish to delete.

13.6.4 Closing the Separations Manager

You must close the Separations Manager before you can use any tool bar buttons or menu options in the RIP.

Click

OK

to confirm all the changes you have make in the Separations Manager and Edit Style dialog boxes. The

OK

button saves the changes you have made and closes the Separations Manager. If you opened the Separations Manager from the Edit Page Setup dialog box, you can also save the changes by clicking the

Select

button. In addition to saving the changes, the

Select

button displays the selected style in the Edit Page Setup dialog box. Click

Cancel

to discard all changes.

Note: If you open the Separations Manager from the Edit Page Setup dialog box, changes that you make in the Separations Manager are independent of the Edit Page Setup dialog box. For example, if you create a separations style, and close the Edit Style dialog box with

OK

, and the Separations Manager with

OK

or

Select

, the new style will remain even if you click

Cancel

in the Edit Page Setup dialog box.

13.7 Edit Style dialog box

The Edit Style dialog box appears when you create or edit a separations style in the Separations Manager. It contains the options related to separations and, where appropriate, to screening. There are two forms of the dialog box:

• If the output format of the separations style supports screening controlled by the RIP, the Edit

Style dialog box contains options that allow you to set up defaults and override the screening

parameters requested in a job. See Chapter 6, “Screening” for a description of these screening

options: try starting with Figure 6.2, page 150.

• Otherwise, a more compact dialog box displays only the options for separations, as shown in

Figure 13.11. This form of the dialog box suits contone output and also output to devices and

processes that do their own screening.

The remainder of this section describes the separations options appearing in both forms of the dialog box.

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Note: There are also controls for black generation for CMYK output and overprinting in the Color

Setup dialog box, accessed from the

Color Setup Manager

or the Separations, Screening, and Color

section of the Edit Page Setup dialog box. (See “Color Setup” on page 358.) Also, trapping options are

available from the Separations, Screening, and Color section of the Edit Page Setup dialog box. (See

“Trapping features” on page 369).

Figure 13.11 Edit Style dialog box

This dialog box contains a list showing the separations that the RIP can produce. There are initially

separations for the process colors in the selected color space. In Figure 13.11 there are separations for

the four process colors in the CMYK color space.

If the chosen output format supports additional colorants, you can control the printing of spot color separations using the

(Other colors in job)

entry, or you can add a separation for a specific spot color.

You can rename or delete spot color separations. You cannot delete the standard process color separations from the list, nor can you change their names. You may, however, ask the RIP not to produce a certain separation.

For particular jobs, you may want to vary the settings in the interests of efficiency or to ensure compatibility with PostScript language code that uses Level 1 operators. For example, the default settings produce separations for all process colors, so you may want to turn off some process colors if a job is mainly defined in spot colors. Also for example, if you need to reprint just a single separation (and it is not saved in the Output Controller), you can turn off all the other separations.

The

Print

option in the Edit Style dialog box determines which separations are produced. The RIP produces all those separations marked as

Yes

and the non-blank separations marked as

Not Blank

.

Note: If you are printing a preseparated job, and you wish to not produce some separations, select

Recombine preseparated jobs

, even if you then wish the RIP to produce output separations. The RIP produces all separations of a preseparated job except when recombining.

If you are producing screened separations, you can control the screening of process and spot colors by

using the screening options in the Edit Style dialog box. See Chapter 6, “Screening” for a description

of these options.

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13.7 Edit Style dialog box

Note: The separations shown in this dialog box always take effect for jobs that do not specify their own separations. If the job attempts to specify separations, you must select the

Override separations in job

check box if you want to produce the separations shown here.

13.7.1 Producing separations

The boxes below the list of separations allow you to control the printing of process color separations and change the ink type. If the chosen output format supports additional colorants, you can also control the printing of spot color separations. Any spot color not explicitly listed is controlled by the

(Other colors in job)

settings. With the default settings, if a job calls for spot colors not named in the list of separations, the RIP converts those spot colors to the appropriate combination of process colors.

To change the settings for an existing colorant, select the colorant from the list and edit the values in the boxes below.

Note: If the output format of the separations style supports screening, you can also change the screen

angle of the process color or spot color separation. See Section 6.5.1, “Changing angles for separations” for details.

Separation

Print

The name of the separation. To rename a spot color separation, type the new name into the text box. You cannot rename process color separations.

Warning: The name you enter for the spot color must match the one used in the job in every respect: upper and lower case, use of embedded space characters and any trailing

CV

or

CU

suffixes. For example: a typical Pantone specification is

PANTONE 386 CV

but applications may report this in different ways.

If this option is set to

Yes

, a page will be produced for the separation, even if the separation is blank. If this option is set to

No

, the page will be omitted, although any effects it might have on the others are still calculated. You might use this feature to suppress process color separation for a job using spot colors only. If the option is set to

Not Blank

, the RIP will produce a page for that separation as long as the separation is not blank.

For example, to produce only the process colors and convert all colors defined as spot colors in the job to process colors, set each process color to

Yes

and set

(Other colors in job)

to

No

. These are the default settings.

To produce a separation for every spot color requested in the job and for each of the process colors, set each process color to

Yes

and set

(Other colors in job)

to

Yes

. Then any calls for unlisted spot colors in a particular job mean that the RIP produces the required separations automatically for that job.

Warning: When Simple Imposition is being used, the

Print

option must be set to

Yes

if you wish to see color patches on either the proofing or the plate colorbars. Using the

Not Blank

option will omit color patches for that color.

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If you want to produce a separation for a specific spot color and to convert all other spot colors which may be included in the job to process colors, set the specific spot color to

Yes

and set

(Other colors in job)

to

No

.

Of these ways, the one you choose is likely to be dictated by the characteristics of your output device and process, such as the number of inks available in one pass.

Angle

This box appears only if you are editing a halftone (screened) style. Enter the

screen angle you want to use for this separation. See “Screen angles” on page

156 for more details of screen angles.

Note: This box defines a default value, used if the job does not set its own screen angles. If you wish to use angles entered here even when the job requests other values, select the check box

Override angles in job

, also in this dialog box.

Note: If you have one of the optional TrapPro features enabled, you can create sets of trapping rules and apply them within the RIP. From the Eclipse Release of the Navigator RIP, the ink set options have been removed from the Edit Separations dialog and placed within their own Ink Set Manager.

TrapPro and the Ink Set Manager options are fully described in the separate TrapPro User Manual.

New

Delete

Use this button to add a separation for a spot color to the list. A new row appears in the list of separations. Type the name of the spot color into the first text box below the list, to replace the text

New Color

. If required edit the settings for

Print

.

Warning: The name you enter for the spot color must match the one used in the job in every respect: upper and lower case, use of embedded space characters and any trailing

CV

or

CU

suffixes. For example: a typical Pantone specification is

PANTONE 386 CV

but applications may report this in different ways.

Use this button to delete the selected spot color separation. The separation disappears from the list. You cannot delete process color separations.

13.7.2 Other options

There are some other controls in the Edit Style dialog box, not linked so closely to individual separations.

Override separations in job

The separations shown in the Edit Style dialog box always take effect for jobs that do not specify their own separations. If the job attempts to specify separations, you must select the

Override separations in job

check box if you want to produce the separations shown here.

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13.7 Edit Style dialog box

Use Level 1 spot colors

Spot color is not a standard part of the PostScript Level 1 specification. It is a widely used convention that was defined later. If you wish to separate composite jobs using this spot color convention, select this box.

Warning: We strongly advise you not to select this box when defining a separation style to which you will supply preseparated jobs. The box is only enabled if you using a CMYK separation style and not recombining, but you might use a style with these settings and submit preseparated jobs in order to override screen angles or other settings. (You cannot select this box when you are using a monochrome separation style or you have selected the

Recombine preseparated jobs

box.)

When you select this box, the RIP converts conventional representations of spot colors in PostScript Level 1 language documents to the current

Post-

Script Language compatibility level

. By default, the RIP converts the spot colors to LanguageLevel 3. To convert the spot colors to LanguageLevel 2 style, change the

PostScript Language compatibility level

in the Page Setup

Options dialog box.

This check box has an effect only when producing spot colors.

Override angles in job

This box appears only if you are editing a halftone (screened) style. Select

this box if you want to ignore any screen angles set in the job. See “Screen angles” on page 156 for more details.

This option is automatically selected when

Recombine preseparated jobs

is checked.

Reject preseparated jobs

If you select the

Reject preseparated jobs

check box, the RIP will not process preseparated jobs. If this check box is selected, then the

Recombine preseparated jobs

check box is disabled.

Recombine preseparated jobs

The

Recombine preseparated jobs

check box allows you to recombine certain classes of preseparated jobs. Recombining may be useful or necessary in a variety of cases: for example, when proofing on a full-color device or retar-

geting from one kind of final output device to another kind. See “Recombination” on page 356 for details of the suitable jobs.

From Eclipse Release SP3, this option will activate Recombine 2.

Note: When using this option, the RIP cannot paint partial page buffers; expect jobs with pages requiring large amounts of memory to fail if you have not allocated enough physical memory.

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13.7.3 Recombination

The Navigator RIP Eclipse Release provides a single method of recombination known as “Recombine

2”. Recombine 1 is replaced completely with Recombine 2 which uses both object and raster methods where appropriate.

Recombine version 2 provides the following main benefits:

• Improved accuracy of object placement.

• Improved accuracy of the recombined color.

• Considerable performance improvements for complex jobs.

• Improved accuracy of color management—color management happens after overprints and recombination has occurred.

The additional functionality may result in a performance overhead proportionate to the area covered by those objects present in separations which are not being output and instead converted to process.

Recombine 2 is active as the default.

There are some limitations on the jobs that the RIP can recombine. There are also some classes of jobs where you should make additional settings.

The limitations listed below apply to Recombine 2:

• The job must consist of process separations, suitable spot colors, where suitable is defined in this section, or both. (It is also possible to submit most composite jobs to a Page Setup using

recombination, but see the comments in “Recombination and composite jobs” on page 357.

This ability minimizes the number of Page Setups that you must create and maintain but has no intentional effect on the composite jobs.)

• The names of suitable spot colors must be unambiguous. If the job supplies a CMYK equivalent for a spot color and the name is recognized by the RIP, that is sufficient for use with recombine.

• When the job does not contain a process equivalent for a spot color, recombine can still be used if the RIP can find a correct equivalent name in a RIP named color database. The RIP searches several files in the

SW/NamedColor

folder for an equivalent. These files define several commonly used names, including: other process colors, such as Red, Green, and Blue; spot colors produced by some common job-creating applications; and the

CV

and

CVU

names defined in

PANTONE Colors.

Note: Some common names—for example,

Pink

or

Mauve

—can have slightly varying definitions in different jobs, because either the creating application or the designer has used a conflicting definition. One solution is to add a CMYK equivalent in the job where such a name occurs.

In short, CMYK equivalents for spot colors must exist either in the job or in a RIP named database.

• The job must contain all the required separations in one file or AppleTalk connection. It is not possible to recombine jobs where each separation is in its own file.

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• Where the job contains more than one set of separations, separations from each set (or page) must appear contiguously—for example each page (or set) should appear in the order,

KCMYDE (where D and E represent spot colors). That is, KCMYDE for the first page,

KCMYDE for the second page and so on. The pages must not appear ordered by colorant. For example: the order KKK…CCC…MMM…YYY… DDD… EEE… is not allowed. Where there is only one set (or page) of separations in the job, the order of separations in the job is unimportant: for example, CMYKDE and KCMYED are both acceptable.

• When Recombine is enabled and a preseparated PDF job is provided that contains

SeparationInfo

objects (a dictionary containing color separation information for the page from PDF v1.3), the RIP will treat each set of separations as a logical page. For example, a job containing

16 separations of CMYK, CMYK and so on, is handled as four (recombined) pages. If

SeparationInfo

is missing or Recombine is disabled, the RIP will treat the job has having 16 pages.

The additional settings for recombined jobs are:

• The

Override angles in job

option is automatically selected when

Recombine Preseparated jobs

is selected. It is highly recommended you leave it selected. In the Edit Style dialog box set

the angle you require for each separation. See “Screen angles” on page 156 for details.

• It is highly recommended that the

Override dot shape in job

option is selected.

• It is highly recommended that the

Override frequency in job

option is selected.

• You can also override other screening features if you wish.

Note: Multi-page imposition cannot be used with recombine. However,

Crop Marks

, or other uses of the

One-Up, single-sided

imposition scheme, (for example, when adding a color bar), can be used with recombine.

13.7.4 Recombination and composite jobs

Recombination is a powerful capability of the RIP. In many cases, it is possible to submit both composite and preseparated jobs to a Page Setup that has

Recombine preseparated jobs

selected. However, there are cases where the nature of the job or other settings made within the RIP mean that it is necessary to create separate Page Setups for composite and preseparated jobs.

13.7.5 Recombine 2 issues

This section contains points to note when using Recombine v.2. It uses much of the same code as is used for PDF 1.4 Transparency and therefore has similar issues:

• Color management of

DeviceRGB

colors with equal color values, that is

R=G=B

, are color managed using the CMYK input profile and not the RGB input profile for all object types except images and shaded fills.

• When recombining preseparated files the

Overprint process colors

options have no effect, even if selected.This means that the

OverprintProcess

,

OverprintWhite

,

Overprint-

Gray

and

OverprintBlack

user parameters are not applied to recombined objects. Instead,

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the overprint effect is equivalent to the result of outputting the separations of the job on a press.

That is, the separations are individually processed (without recombine) and the results are overprinted—much the same as using ROAM for all separations for a given page together.

• When recombining composite files (that is, composite files that have been input to a recombine setup), the settings of the

Overprint process colors

options in the GUI are obeyed.

• If composite jobs are put through a recombined setup using Recombine v2 and color management, the color management is implemented after any compositing for transparency and after any overprints have been resolved.

13.7.6 Closing the Edit Style dialog box

You must close the Edit Style dialog box to save your changes. You must also close the Separations

Manager before you can use any other part of the RIP.

Click

OK

to confirm all the changes you have made in this use of the Edit Style dialog box, including any deletions. This confirmation is provisional: you must also click

OK

or

Select

in the Separations

Manager to finally save your changes. Click

Cancel

to discard your changes immediately.

13.8 Color Setup

If you wish to create a setup with Color management including, ICC profiles, custom rendering intents or perform press emulation on a proofer, you should use the ColorPro option. This option is activated by a password and you should contact your dealer for more information.

If you do have ColorPro activated in your Navigator RIP and you wish to create a setup with color management, you should consult the ColorPro User Guide.

13.8.1 Define color setups (no color management)

Follow these steps to create a customized color setup. Note that a color setup corresponds to a particular device and color space.

1. Choose

Color > Color Setup Manager

. The Color Setup Manager dialog appears.

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Figure 13.1 Color Setup Manager dialog box

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13.8 Color Setup

2. In the Color Setup Manager dialog box, select the device for which you want to create a color setup. If you are creating CMYK Separations (halftone), you should select

Printing Press

in this option.

3. If necessary, select the color space for which you want to create this color setup. Note that when you create a Page Setup, the separations style you choose determines the color space of the Page

Setup.

4. At this point you have the option to select either,

New ‘No Color Management’ setup

, or

New

‘ColorPro’ setup

(which is only available by use of a password). If you can select

New

‘ColorPro’ setup

, you should consult the ColorPro User Guide for more details.

Figure 13.2 New Color Setup dialog box

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The following tables describe the options available in this dialog.

Table 13.1 Input Document Controls in the New Color Setup dialog box

Fields

Override color management in job

Override overprint mode in job

Description

Select this check box to override any color management supplied in the job and use the options set in this dialog box.

If you do not check this box, the Navigator RIP searches the job for a color space array, embedded ICC profile, or a color space resource. If there is such an element, the

Navigator RIP uses it to transform the relevant object on the page and then treats the object as defined in device-

independent color. See Appendix B, “Jobs Containing

Color Management Data” for details.

Note: A PDF/X-3 file containing an

OutputIntents dictionary will be color managed using the ICC profile indicated by the

OutputIntents

dictionary, as long as the job uses a device independent color space and the

Override color management in job

option is not selected

A PostScript language operator called

setoverprintmode

which is the PostScript language equivalent of the PDF gstate

OPM

flag.

If an object is set to overprint and

OPM

or

setoverprintmode

is on, the Navigator RIP drops any colorants which have a zero value. This is called

“implicit overprinting”.

This is what the

Override overprint mode in job

option controls.

If the

Override overprint mode in job

option is checked, the

Overprint process colors

option (described below) is always honored and any

overprintmode

and

OPM

parameter in the job is ignored. If it is not checked, any

overprintmode

and

OPM

parameter in the job will be used and the

Overprint process colors

setting will be used as the default value.

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Table 13.1 Input Document Controls in the New Color Setup dialog box (Continued)

Fields

Overprint process colors

Drop white objects

Overprint grays

Description

If this option is selected and overprinting is switched on for an object, the RIP overprints any process color component defined as

0

in the CMYK color space, or as

1

in the RGB color space. That is, the component is treated as transparent.

When this option is not selected, a process color component produces a knockout on the separation. However, if overprinting is switched on for an object, the RIP overprints colorants that are explicitly set to overprint using the Harlequin extension to

setcmykcolor

.

When

Overprint process colors

is selected,

Drop white objects

determines how the RIP handles white objects: objects defined as

0 0 0 0 setcmykcolor

,

1 setgray

, or

1 1 1 setrgbcolor

.

If this option is selected and overprinting is switched on for that object, the white object simply disappears from the separations.

If this option is not selected, the white object knocks out underlying objects, even when overprinting is switched on.

By default, this option is not selected.

Select this object to enable the Cyan, Magenta, and

Yellow colorants to be overprinted rather than knocked out when a color is specified as gray (with the PostScript language

setgray

operator or spot color converted to a gray level) and the job requests overprinting. This behavior is not defined by the PostScript language, and though it is unusual for a job to rely on it, sometimes a job will assume this, especially when the gray tint arises from a named Black spot color which is converted to process.

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Table 13.1 Input Document Controls in the New Color Setup dialog box (Continued)

Fields

Overprint gray images

Overprint 100% black

Image only black

Description

Overprint behavior changed from Navigator RIP version

4.1 to 5.x and beyond. While the old behavior is deemed incorrect, there is a desire to selectively use the old behavior because of the un-predictability of some graphic applications and to provide for end-users the ability to handle legacy work.

The user parameter is called

OverprintGrayImages

, with a default of

true

which when set overprints gray images. If it is set to

false

, gray images will knock out of CMY backgrounds.

When this option is selected, the RIP overprints 100% black rather then generating knockouts in the other separations. The black channel or separation is generated as normal but, depending upon the characteristics of the other inks, may need to be applied last in the combination process so that it overprints all colors necessary. If this option is selected, overprinting occurs regardless of whether overprinting is switched on for that graphics object. How the overprinting of the other separations is done depends on the

Image only black

option.

There is no performance penalty incurred by using this feature—in fact, it may be slightly faster to overprint, given that knockouts do not have to be calculated.

This feature only applies to black objects, not to individual pixels of a continuous tone image that happen to be 100% black.

This option controls whether solid black objects appear in the process color separations other than Black when the

Overprint 100% black

option is selected. If this box is selected, the RIP ignores the other process color components of black objects and no trace of the objects appears in those separations. If this box is not selected, then the other process color components are taken into account. If this box is not selected, the objects appear in any separation where the color component is defined as non-zero in the CMYK color space (or not

1

in the RGB color space).

Process color components defined as

0

in the CMYK color space or

1

in the RGB color space are always overprinted.

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13.8 Color Setup

Table 13.1 Input Document Controls in the New Color Setup dialog box (Continued)

Fields

Use late color management

Description

Color management modules prior to the Navigator RIP

Genesis Release

™

instigated color management at the front-end of the process, (with the exception of recombine jobs where color management was applied at the back-end of the process). Applying late color management gives better quality results with blended colors.

Note that late color management is disabled when calibration strips are printed.

See “Notes on Use late color management” on page 364

for more information.

Table 13.2 Input Separation Detention angles in Job options in Color Setup dialog box

Fields

Cyan

Magenta

Yellow

Black

Description

The angles specified in these fields help the ColorPro application detect the individual plates within a job. The default angles will usually work.

If you do change one of these values, for example Cyan to 30°, and the incoming job has Cyan at 15°, you will encounter problems.

Table 13.3 Output Controls for RGB options in the New Color Setup dialog box

Fields

Black generation

Override black generation in job

Description

This is the process of computing how much, and where, black should be added to the image.

This option determines how much black ink should be used to reproduce colors. Select

Ignore, Minimum

,

Light

,

Medium

,

Heavy

,

Maximum

or

UCR

from the menu.

Undercolor removal (UCR) is the process of reducing the amount of other colors present where the black is added.

Rarely, a job will specify black generation itself. You can force the scheme set in the Color Setup dialog box to override those set by the job, by selecting this check box.

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Table 13.3 Output Controls for RGB options in the New Color Setup dialog box

Fields

Max. ink

Max. black

Convert RGB to true black

Description

This value constrains the maximum amount of all four

CMYK colors that will be generated in the conversion process. Similarly, colors specified explicitly as black are not affected by this.

This value is the maximum amount of black ink that will be generated by the color conversion process. Note that colors specified explicitly as black are not affected by this setting.

Some applications, and especially Microsoft

®

Word, use

RGB colors for everything, including solid black— coded as

0 0 0 setrgbcolor

(or

0 0 0

in a

DeviceRGB

color space). You should choose this option to force the RIP to intercept blacks coded in this way and convert them to (

0 0 0 1

in) a CMYK color space.

After setting options in the New Color Setup dialog box, click

Save As

and assign a name to this color setup. The Color Setup Manager dialog box displays the new color setup that you have created. Note that you can also Edit, Copy, and Delete color setups from the Color Setup Manager.

5. Click

OK

to confirm all the changes you have make in the Color Setup Manager and New Color

Setup dialog boxes.

The

OK

button saves the changes you have made and closes the Color Setup Manager. If you opened the Color Setup Manager from the Edit Page Setup dialog box, you can also save the changes by clicking the

Select

button. In addition to saving the changes, the

Select

button displays the selected color setup in the Edit Page Setup dialog box. Click

Cancel

to discard all changes.

13.8.2 Notes on Use late color management

The

Use late color management

option has been introduced in the Navigator Genesis Release

™

to overcome problems with color managing blended colors. In this context, blended colors means both the compositing of transparency in PDF jobs, and also the overprinting of opaque objects in PostScript language and PDF files.

In order to color manage blending correctly, the blending must be performed in the same color space that the designer worked in when creating the job. For example, SWOP with a range of Pantone colors. In theory, if this type of job is printed on a SWOP press that supports all the Pantone colors present in the job, the rendering of the blends will be correct.

Problems arise when the job is printed to a device with different characteristics to the color space the designer worked in. A typical usage is the need to color manage the job when printing to a proofing device. In this case, to reproduce the blending the designer intended, the blending should be performed in SWOP and result then color managed to the proofing device. Historically, this has been dif-

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ficult to do accurately without using a form of “double pass” RIP processing. That is, the job is RIP processed once to (for example) TIFF, in which the blending is in SWOP. The second RIP pass then color converts the TIFF and outputs the result to the proofing device.

When the

Use late color management

option is off, the Navigator RIP will perform color management of colors in the job before blending of either transparency or overprints. The RIP performs blending by using the available information to make a “best guess” at the blended colors, but at a late stage in the RIP process and without full knowledge of the color values and other graphics state attributes. This method usually makes the blended regions visible, although they are not correctly color managed. And if spot colorants are converted to process colors, overprinting of these objects is disabled by default.

When the

Use late color management

option is selected, color managed blending is performed in a single pass of RIP processing with its obvious efficiency benefits. The Use late color management option is available on both ColorPro and

No color management

color setups.

The option is available in

No color management

setups to achieve better rendering of overprinted spot colors. For accurate proofing of jobs containing transparency and/or overprints, it is recommended that the

Use late color management

option is used.

Please note the following points when using late color management:

• The definitions of tint transforms of spot colors in the job (which are used to derive the CMYK equivalents) will only be used to derive the CMYK equivalent of the 100% color value. Tints will be rendered with CMYK values derived from the 100% spot.

• If a job contains multiple color spaces of the same spot color, and where there are multiple definitions of the tint transform, only the first tint transform encountered will be used; as above.

• Special treatment of

DeviceRGB

and device independent colors in the job is currently required.

That is, the RIP will first color manage these color spaces to a CMYK color space defined by the CMYK input profile. If this is not defined, or a

No color management

setup is used,

SWOP

(CGATS TR001

) will be used. The downside of this method is that the CMYK input profile may restrict the gamut of the colors in the job for these color spaces to less than the gamut of the output device.

• Late color management is forced on when used with recombine and also when outputting to a

DeviceN

device, such as a Hexachrome device.

• Late color management is disabled when calibration strips are printed.

13.8.3 Overprinting controls

Where 100% process black is present and in other circumstances, you may wish to perform overprinting rather than causing knockouts in the other separations. This applies both to composite color output

and to screened output. (See “Knockouts and overprinting” on page 343 for an introductory discus-

sion.)

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13.8.3.1 Color managed overprints for DCS

DCS (Desktop Color Separation) jobs that contain spot color data must be overprinted for good quality output. If the output device does not support those spot colorants, the resulting output will be inaccurate, with a warning that the spot color is missing.

With the introduction of backdrop rendering the RIP has the ability to interpose a virtual device which does support those spot colors, and where correct overprinting will result. The RIP can then color convert the backdrop to the final output producing accurate results.

A way of using backdrop rendering is to set Recombine within the RIP user interface. For more infor-

mation see “Recombination and composite jobs” on page 357. You should note that RIP performance

is affected by backdrop rendering because the RIP implements color managed overprints by compositing rather than direct rendering.

13.8.4 Black generation and undercolor removal

With regard to the CMYK color space, in principle, all colors can be represented with cyan, magenta, and yellow. In practice, however, the theoretically correct combination of these three colors will not produce the color expected when printed, because of the limitations of inks.

To overcome this practical problem, pure black ink is used to improve color reproduction on the printed page. This is the role of the K or black separation. Black is added to produce pure black on the page, because using a combination of cyan, magenta, and yellow usually gives dark brown, rather than black, when printed. Therefore, black text is printed with black ink.

Black is also added in color regions of an image to strengthen color tones. The application of black can often be very effective for improving an image. The amount used can be varied according to the effects you wish to achieve.

Black generation is the process of computing how much, and where, black should be added to the image.

Note: If you have ColorPro available, it is able to add black in ways more subtle than the controls described here, using Color Rendering Intents. See the separate ColorPro User’s Guide for details.

When converting color descriptions expressed in RGB (or in HLS, device-independent color, or other spaces which end up as RGB) to CMYK for printing, the RIP must decide how much of a color is to be represented by black ink, and how much by the others. Because a perfect theoretical description of the color image is provided by the CMY components, if black is added without the appropriate removal of some of the cyan, magenta, and yellow, the color produced on the printed page will not be the one intended.

Undercolor removal (UCR) is the process of reducing the amount of other colors present where the black is added. The legend ucr represents undercolor removal in the graphs later in this section.

Note: The black generation settings in this dialog box operate in the RIP without ColorPro. With ColorPro enabled, an alternative method is normally used. The settings made here are used with ColorPro only when sending RGB data direct to a four-color device, without first converting to a device-independent color space.

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13.8.5 Black generation

You can specify how black generation and undercolor removal should be done in the New Color

Setup dialog box. The settings in this dialog box control the way the RIP will apply black by constructing internal calls to the PostScript language operators setblackgeneration

and setundercolorremoval

. The dialog box offers a number of black generation schemes. Factors that you should take into account when selecting a scheme include the qualities of the various inks (discussed

in “Ink densities” on page 369) and printing media.

The scheme used is controlled by the

Black generation

drop-down list. The options are:

• Ignore

• Maximum

• None (the default)

• Light, Medium, and Heavy

• UCR

Sections 13.8.5.1 through 13.8.5.5 describe these options.

Rarely, a job will specify black generation itself. You can force the scheme set in the dialog box to override those set by the job, by selecting the

Override black generation in job

check box.

13.8.5.1 Ignore

This option does not set black generation and undercolor removal. It replaces as much color as possible with black, while maintaining the intended color, irrespective of ink densities. Because no Post-

Script language code for performing undercolor removal is generated, it is the fastest method.

13.8.5.2 Maximum

K, ucr

CMY

This option introduces a lot of black, taking into account the maximum black ink density. Specify the maximum black ink density in the adjacent

Max black

text box as a percentage value, as described in

“Ink densities” on page 369.

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13.8.5.3 None

CMY

K, ucr

This option performs no black generation or undercolor removal. Black is represented as a mixture of cyan, magenta, and yellow, leaving only those colors expressed explicitly in the PostScript language job as black—rather than as a mixture of red, green, and blue, or as device independent color—to be rendered on the black separation.

13.8.5.4 Light, Medium, and Heavy

Light

K

Medium

K

CMY

CMY ucr ucr

Heavy

K ucr

CMY

These options introduce black gradually, according to exponential functions, with proportionately smaller amounts of black added and color removed for the lighter colors than the darker ones. This is

again subject to the constraints of maximum ink densities, specified in the adjacent boxes. See “Ink densities” on page 369 for details of controlling these ink densities.

13.8.5.5 UCR

K

CMY ucr

Instead of an exponential curve, this option adds no black until the maximum colored ink density is reached and then adds black linearly up to its maximum. The maximum colored ink density is the

maximum ink density value minus the maximum black density value. See “Ink densities” on page 369

for details of controlling these ink densities.

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13.9 Color separation angles in job

13.8.6 Ink densities

Most of the black generation styles are affected by the ink densities set in the two Max ink and Max black options in the black generation section of the Color Setup dialog box.

You should select these values with consideration for paper and press characteristics.

13.9 Color separation angles in job

The RIP sometimes needs to identify which colors are represented in jobs: for example, when recombining a preseparated job. Often there are well structured identifiers that give the answer directly and unambiguously.

Where there is not an obvious identifier, the RIP analyzes the contents of the job to decide a likely color. The screen angle is one of the items that the RIP analyzes.

Under the label

Color separation angles in job

, set the

Cyan

,

Magenta

,

Yellow

, and

Black

text fields to the screen angles that the incoming job uses for these colors.

Note: The angles in this section are the screen angles expected in the incoming job, not the angles used for output. The angles used on output are set in the Edit Style dialog box, and can be entirely different.

13.10 Trapping features

Trapping options are found in the

Trapping

section of the Edit Page Setup dialog box and gives some control over trapping; that is, overprinting edges of objects in the output to avoid white gaps showing when printed due to slight misregistration.

If your copy of the RIP has the one of the optional TrapPro features enabled, you can create sets of trapping rules and apply them within the RIP. TrapPro is fully described in the separate TrapPro User

Manual. (You must enable TrapPro by obtaining a keyword and selecting the

TrapPro item while

following the procedure described in “Switching on HSL” on page 172 of this manual.)

Making full use of trapping in the RIP can require the choice of appropriate options both in the applications creating the PostScript language job and in the RIP.

From Navigator RIP Eclipse SP1, PDF jobs containing PJTF (Portable Job Ticket Format) structures that detail trapping parameters are supported with respect to making the parameters available to Trap-

Pro. Previously, PJTF structures were ignored. Therefore, if TrapPro is enabled (that is, just the password entered, not necessarily any parameters set established via the GUI), a PDF job containing trapping parameters (via PJTF structures), will be trapped as dictated by those parameters.

13.10.1 Trapping and QuarkXPress

The Navigator RIP supports trapping facilities provided by QuarkXPress and its settrap

PostScript language extension.

QuarkXPress has the ability to generate arbitrary trapping. It can do so in either of two ways:

• By including explicit overprinted borders in the PostScript language page description it produces. This method works on all RIPs but may produce large job files.

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Color Separation

• By indicating that a capable RIP should generate the trapping. The RIP can do this if you select the settrap (Quark)

option. The QuarkXPress operator must use a printer description file declaring that the RIP supports this feature. Using this option allows QuarkXPress to generate more compact PostScript language code, which saves disk space and may lead to faster interpretation by the RIP.

13.10.2 Controls in the Navigator RIP

The

Trapping

drop-down list in the

Trapping

section of the Edit Page Setup dialog box always provides the following options:

None

This option performs no trapping.

settrap (Quark)

Use this option to have the RIP generate overprinted borders according to

instructions embedded in suitable jobs by QuarkXPress. See “Trapping and

QuarkXPress” on page 369 for details of how to produce suitable jobs.

If your copy of the RIP has one of the optional TrapPro features enabled, there may be extra entries in this list and you also can create new sets of trapping rules that also become entries in this list, as described in the separate TrapPro User Manual.

13.11 Pages in the Output Controller

In general, the RIP treats separations the same way whether they are the result of processing a preseparated job or the result of separating a composite color job within the RIP.

Depending on the separations style, each page of a composite color job can produce several pages, one for each separation. Once these pages are in the Output Controller, the RIP handles them in the same way as any other pages.

The pages are tagged with their color, which appears after the name in the Output Controller. For example, the job picture.ps

separated for CMYK printing would have four entries in the queue, as follows:

picture.ps (C) picture.ps (M) picture.ps (Y) picture.ps (K)

Cyan, magenta, yellow, and black are abbreviated to C, M, Y, and K respectively. Red, green, and blue are abbreviated to R, G, and B respectively. Spot color separations are tagged with the full name of the separation.

13.11.1 Roaming separations

When you view a separation on a color display, using

Roam

, it is displayed in the appropriate color, at least until you choose to change that display color. The Roam window also displays the title of the page, an abbreviation for the color, and the resolution. Cyan, magenta, yellow, and black are abbreviated to C, M, Y, and K respectively. Red, green, and blue are abbreviated to R, G, and B respectively.

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13.11 Pages in the Output Controller

An asterisk character (

*

) indicates a spot color separation, and a percent character (

%

) indicates grayscale.

Shift

You can view a block of several separations at once. Click to select the first one, then hold down the

Shift key and click to select the last one.

When you view multiple separations, the colors are overlaid to give an impression of how they will look when combined on paper. For example, in a high-resolution screened picture, you should be able

to see the rosettes of the screen pattern. (See Chapter 6, “Screening”, for more discussion of viewing

superimposed screens.)

You can roam a separation in a different color, which can be useful, for example, if you want to see the differences between two separations of the same color. To highlight the differences, change the roam color of one page and then roam the pages together. For details of changing the roam color, see

“Changing the color in Roam” on page 371

For more information on roaming, see “Roam and Preview windows” on page 84.

13.11.2 Roaming composite pages

When you view a composite page using Roam, by default the RIP shows all the separations in the composite page together.

You can reduce the number of separations that you can see in the Roam or Reduced Roam window

using the Roam Options dialog box. See “Roam Options and Preview Options dialog boxes” on page

85 for details.

13.11.3 Changing the color in Roam

You can inspect and change the colors displayed in the Roam window for the colorants in individual separations and composite page buffers. To do this, select a page buffer in the Output Controller, click

Info

, and in the Info dialog box click

Change roam color

. Figure 13.12 shows the dialog box that

appears.

Note: You cannot inspect or change the roam color while you are roaming a page buffer from any page in the same job.

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Figure 13.12 Change Roam Color dialog box

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Color Separation

The Change Roam Color dialog box appears with a table displaying all the colorants present in the selected page buffer. The columns in the table are:

Colorant

This is the name of the colorant in the page buffer. In a separation, there is only one colorant. In a composite page buffer, all the included colorants appear. (Typical composite page buffers contain only process colors but, for a small number of output plugins, there can also be spot colors.)

Red

Green

This is the red component of the roam color, in the range 0 (zero) through 1.0.

This is the green component of the roam color, in the range 0 (zero) through

1.0.

Blue

This is the blue component of the roam color, in the range 0 (zero) through

1.0.

Roam Color

This is the name of the roam color. In an unchanged page buffer this is the same name as appears in the

Colorant

column. In a changed page buffer, the color is the last one chosen for this colorant. You can substitute any other color by choosing from a list of common colors or by typing new values.

To change a color, first select it by clicking on its row in the table. The boxes at the foot of the table display the RGB values and the name of the roam color for the selected colorant. You can choose named colors from a list or specify any other color by RGB values:

• To select a named color, use the drop-down list for

Roam Color

. The listed values are any special colors represented in this page buffer, a list of default colors for the RGB and CMYK spaces (

Default Red

and so on), and an entry called

Other

. You cannot select

Other

: it shows only that you have edited the RGB values to a color not in the list. To return to the original roam color for a colorant, use the list to select the name that appears in the

Colorant

column.

• To specify any color not in the drop-down list, edit the values in the fields for

Red

,

Green

, and

Blue

. Once you have edited a value then, as soon as you move to another field (or select a different row in the table), the

Roam Color

name for the edited colorant changes to

Other

. If you want to edit another color, click on its row. (You can do this for all colorants if you wish; each can have its own value for

Other

.)

Click

OK

in this dialog box and

OK

again in the Info dialog box to save your changes to roam colors.

Click

Cancel

in either dialog box to abandon your changes.

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