Working with Spot Colors and Separations

Accidentally using spot colors such as red and Pantone 111 (say, for picture and text box frames ) in a document that contains four- color TIFF and EPS files is very easy. The result is that InDesign outputs as many as six plates: one each for the four process colors, plus one for red and one for Pantone 111.

The Ink Manager dialog box

That's where the Ink Manager dialog box comes in. Accessed via the Output pane's Ink manager button, this dialog box gives you finer controls over how color negatives output. Figure 31-10 shows the dialog box.

Figure 31-10: The Ink Manager dialog box.

Most users will use the All Spots to Process check box at the bottom of the dialog box. Checking this box converts all colors to CMYK, reducing the print job to four plates (cyan, yellow, magenta , and black). Obviously, if you want to print a spot color on its own plate ‚ perhaps a neon, metallic, or hard-to-simulate color like green or orange ‚ you should not use this option. Instead, make sure that only the colors you do want to output to separate negatives are listed in the Ink Manager dialog box or in the Output pane.

If any colors should have been converted to process color but weren't, you have two choices:

• Override the spot color in the Ink Manager dialog box by clicking the spot color (circle) icon to the left of the color's name . That will convert it to a process color. (Clicking the process color icon, a four-color box, converts a color back to a spot color.) This is the way to go for a quick fix.

• Close the Ink Manager and Print dialog boxes, and edit the color incorrectly set as a spot color in the Swatches pane (Window ‚ Swatches, or F5), as covered in Chapter 8, to make it a process color instead. This will ensure that the color is permanently changed to a process color for future print jobs.

The other Ink Manager options are for experts and should be changed only in consultation with your service bureau and commercial printer:

• You can change the ink type, in the Type pop-up menu. Most inks ‚ including the process inks ‚ should be left at Normal. Use Transparent for varnishes and other finishes that let color through ‚ you don't want InDesign to trap to such "colors"; if they did, no color would print under the varnish or finish. (A varnish is often used to highlight part of a page, such as making the text reflective in contrast to the rest of the page.) Use Opaque for metallics, pastels, and other thick colors; this setting will let adjacent colors trap to the edge of opaque objects, but it prevents trapping of underlying colors (since they will be totally covered over). Finally, use OpaqueIgnore for inks that don't trap well with any other color ‚ your service bureau or commercial printer will tell you when you need to do this.

• For each ink, you can change the neutral density, which tells InDesign how to handle the trapping of differently saturated inks. For example, a dark color (highly saturated) will need to be trapped more conservatively against a light color to prevent excess intrusion. In coordination with your commercial printer, you might want to override the default neutral density settings if you're finding that the defaults don't properly handle some trapping combinations. It's possible that your commercial printer is using a different brand of ink than is assumed in the settings, for example, and that could require a density adjustment.

• Some commercial printers let you arrange the order in which color negatives print. This affects the trapping, because InDesign presumes that the colors are printed in the standard order ‚ cyan, then magenta, then yellow, then black, then any spot colors ‚ and factors that into its trapping adjustments. In some cases, changing the printing order can improve a publication's color balance, because it happens to favor a range of tones that the standard order might not treat properly. For example, if there's a lot of black in the background, you might want to print black first, so other colors overprint it, giving it a warmer feel than if black were printed on top of the other colors as is normal. To change the order of output used by InDesign's trapping calculations, select a color, and change its ink sequence number in the Trapping Sequence field; all other colors' sequences will be automatically adjusted.

• Use the Ink Alias pop-up menu to apply a process color's settings to a spot color. I don't recommend you do this very often, as it will make the spot color print each dot over the dots of the selected process color, rather than be offset slightly so the color remains visible. You'd set an ink alias only if you were using a spot color in place of a standard process color ‚ such as substituting a yolk color for standard yellow to create a special effect. In this case, the yolk color would overprint the yellow color, replacing the yellow where both colors happened to be used.

Process colors

By default, each color defined in InDesign is set as a spot process color. And each spot color gets its own negative (plate), unless you specifically tell InDesign to translate the color into process colors. You do so when defining a new color by selecting the Process option in the Color Type pop-up menu in the Swatch Options dialog box, described in Chapter 8, when you create or edit a color in the Swatches pane (Window ‚ Swatches, or F5). No matter whether a color was defined as a process or spot color, you can also choose the All to Process option in the Print dialog box's Output pane's Ink Manager dialog box when printing to convert all spot colors to process colors.

If your work is primarily four-color work, edit the spot colors in the Swatches pane to make them process colors. If you make these changes with no document open , they become the defaults for all new documents.

If you do some spot-color work and some four-color work, duplicate the spot colors and translate the duplicates into process colors. Make sure that you use some clear color-naming convention, such as Blue P for the process-color version of blue (which is created by using 100 percent each of magenta and cyan).

The same is true when you use Pantone colors (and Trumatch, Focoltone, Toyo, and DIC colors). If you do not select the Process option in the Swatch Options dialog box, these colors are output as spot colors. Again, you can define a Pantone color twice, making one of the copies a process color and giving it a name to indicate what it is. Then all you have to do is make sure that you pick the right color for the kind of output you want.

Tip ‚  

You still can mix process and spot colors if you want. For example, if you want a gold border on your pages, you have to use a Pantone ink because metallic colors cannot be produced via process colors. So use the appropriate Pantone color, and don't select the Process option when you define the color. When you make color separations, you get five negatives: one each for the four process colors and one for gold. That's fine because you specifically want the five negatives.

Color and separations preview

One thing to be careful of in computer-based layout is that on-screen colors interact differently than they do when printed. When inks overlap, the colors mix to produce a new color ‚ cyan on yellow makes a green, for example. On-screen, cyan on yellow shows cyan where the two overlap. To compensate for that, InDesign can simulate color overprinting. To do so, choose View ‚ Overprint Preview, or type Option+Shift+ z +Y or Ctrl+Alt+Shift+Y. You should have this on as your default so what you see on-screen better represents what will print.

New Feature ‚  

InDesign CS now lets you preview color separations in your document with the new Separations Preview pane.

You can preview your color separations, as well as overprinting any other output, using the new Separations Preview pane (Window ‚ Output Preview ‚ Separations, or Shift+F6). Figure 31-11 shows the pane and its palette menu. By clicking each color and then the eye icon, you can turn on or off specific color plates; InDesign will adjust what appears on-screen accordingly . To see just the CMYK plates, you can click the CMYK color (instead of turning on the cyan, yellow, magenta, and black plates individually). You can also hide all process colors the same way, so only spot colors are visible.

Figure 31-11: The Separations Preview pane.

If you select Show Single Plates in Black in the palette menu and have the eye icon selected for only one plate, InDesign will show that plate in black on-screen. That's because it's often hard to see colors like magenta, yellow, and cyan clearly when they're by themselves .

And if color management is turned off, you can choose the Desaturate Black option in the Separations Preview pane's palette menu. This will convert any black objects overprinting other color objects to 80 percent black so the other objects are more visible during the preview.

The Separations Preview pane also lets you open the Ink Manager dialog box, covered earlier in this chapter.

QuarkXPress User ‚  

InDesign and QuarkXPress offer similar levels of color output controls, but InDesign does have several options QuarkXPress does not. One is setting ink density, another is automatic calculation of screen angles for spot colors. A third is the ability to more accurately preview documents with overprinting colors.

Screen angles

Normally, you'd probably never worry about the screening angles for your color plates. After all, the service bureau makes those decisions, right? Maybe.

If you have your own imagesetter, or even if you're just using a proofing device, you should know how to change screen angles for the best output. If you're working with spot colors that have shades applied to them, you'll want to know what the screen angles are so that you can determine how to set the screening angles for those spot colors.

Screening angles determine how the dots comprising each of the four process colors ‚ cyan, magenta, yellow, and black,_or any spot colors ‚ are aligned so they don't overprint each other. The rule of thumb is that dark colors should be at least 30 degrees apart, while lighter colors (for example, yellow) should be at least 15 degrees apart from other colors. That rule of thumb translates into a 105-degree angle (also called ‚ 15 degrees ‚ it's the same angle) for cyan, 75 degrees for magenta, 90 degrees for yellow, and 45 degrees for black.

But those defaults sometimes result in moir ƒ patterns, which are distortions in the image's light and dark areas caused when the dots making up the colors don't arrange themselves evenly. With traditional color-separation technology, a service bureau would have to adjust the angles manually to avoid such moir ƒ s ‚ an expensive and time-consuming process. With the advent of computer technology, modern output devices, such as imagesetters , can calculate angles based on the output's lpi settings to avoid most moir ƒ patterns. (Each image's balance of colors can cause a different moir ƒ , which is why there is no magic formula.) Every major imagesetter vendor uses its own proprietary algorithm to make these calculations.

InDesign automatically uses the printer's PPD values to calculate the recommended halftoning, lpi, and frequency settings shown in the Output pane of the Print dialog box. But for spot colors, it's basically a guess as to what screening angle a color should get. The traditional default is to give it the same angle as yellow, since if a spot color's dots overprint yellow dots, the effect will be less noticeable than if it overprinted, say, black dots. But if you have multiple spot colors, that approach doesn't work. In that case, choose a screening angle for the color whose hue is closest to the spot colors. Fortunately, InDesign will calculate a recommended angle for you, so you don't have to make any guesses. As always, don't forget to consult your service bureau or printing manager.