Spot Colors

We discussed RGB colors and CMYK inks before, but there is an additional "color space" called spot colors. A spot color is a specified ink color that printers can use to reproduce a color exactly. There are different ways of specifying colors, and one of the most popular in the United States is the Pantone Color Matching System. Pantone publishes a guide of specific named colors. When you specify a Pantone color, your printer knows exactly what color you want because he uses the same Pantone guide to know what ink to put on press.

Spot colors play a very specific role in Photoshop (they play a much larger role in applications such as InDesign and Illustrator). Photoshop can create spot channels, in which a channel is specified as a spot color. Additionally, spot colors are used when you are creating photos that will print entirely in one or several different custom colorsmost commonly, duotones.

Spot Channels

Just as there are channels in your document for RGB or CMYK plates, you can have channels for spot color plates. You can add a spot channel by opening the Channels palette and choosing New Spot Channel from the palette flyout menu (see Figure 5.137). The benefit here is that you can specify an exact color so that you can get a better preview onscreen. From the New Spot Channel dialog box, click on the color proxy to open the Color Picker. You can then choose from any of several standard spot color libraries.

Figure 5.137. Creating a spot channel.

Did you Know?

Anything that appears on a spot channel will separate on its own spot color plate when printed from an application such as InDesign CS2.

Monotones, Duotones, Tritones, and Quadtones

By far, the most common use of spot color in Photoshop is related to multitone files, which include monotones, or images that are entirely one spot color; duotones, or images that consist of two spot colors; tritones, or images containing three spot colors; and quadtones, which are images that containyou guessed itfour spot colors.

Duotones are mainly used to add color or style to print jobs that are printing in only two spot colors. Multitone files can also be used to add tonal depth to an imagereason enough that some photographers and printers will print black-and-white photos as duotones made up of black and gray.

To create a multitone file, you must first make sure that your file is in Grayscale mode. If it isn't already, choose Image, Mode, Grayscale. You can then choose Image, Mode, Duotone to open the Duotone Options dialog box. From the Type pop-up menu at the top of the dialog box, choose one of the four options (see Figure 5.138).

Figure 5.138. Choosing to specify a duotone from the Duotone Options dialog box.

By the Way

For most applications to print duotones correctly, they must be saved as Photoshop EPS files. Illustrator and InDesign will also accept duotones saved as Photoshop PDF files.

Three settings exist for each ink:

• Curves Click on the Curves box to edit the duotone curve values for each ink color (the same way you adjusted curves earlier in the chapter).

• Ink Color Click on the ink color proxy to choose the ink color.

• Ink Name Enter the name for the ink. If you choose a color from the Color Picker, a name automatically is added for you.

Did you Know?

The ink name is extremely important in spot color workflows. To avoid having multiple plates separate for the same spot color, make sure that the spot color name in Photoshop and the spot color name in your page-layout application are the same.

If fooling around with duotone ink curves isn't your thing, you can use one of several settings that the folks at Adobe were kind enough to include with Photoshop. Click on the Load button in the Duotone Options dialog box and navigate to the Adobe Photoshop CS2, Presets, Duotones folder, where you can choose from duotones, tritones, and quadtones. Don't worry about the colors that are in these presetsyou can easily change the colors yourselfbut the valuable parts of these files are the curve settings. Experiment with different presets to find one that suits your needs.