Spot Color versus Process Color

Earlier in this chapter, I mentioned briefly that there are two types of colors that InDesign works with: spot and mixed. Understanding how these differ is key to using them effectively and saving hassles and money when printing your documents.

Several forms of color are used in printing, but the two basic ones are process color and spot color.

Process color refers to the use of four basic colors ‚ cyan, magenta , yellow, and black (known as a group as CMYK ) ‚ that are mixed to reproduce most color tones the human eye can see. A separate negative is produced for each of the four process colors. This method, often called four-color publishing, is used for most color publishing.

Note ‚

Like CMYK, RGB and LAB are also created by mixing colors, so InDesign refers to all such colors as mixed colors , leaving the term process color for CMYK, since that's an industry standard term for CMYK.

Spot color refers to any specific color ink ‚ whether one of the process colors or some other hue ‚ used for specific elements in a document. For example, if you print a document in black ink but print the company logo in red, the red is a spot color. A spot color is often called a second color even though you can use several spot colors in a document. Each spot color is output to its own negative (and not color-separated into CMYK).

Using spot color gives you access to special inks that are truer to the desired color than any mix of process colors can be. These inks come in several standards, with Pantone being the most popular. Trumatch, Focoltone, Toyo, and DIC are less popular but still common standards, with Trumatch used mainly in Asia, Focoltone in Europe, and Toyo and DIC in Japan. InDesign supports all five spot-color standards.

Spot-color inks can produce some colors that are impossible to achieve with process colors, such as metallics, neons, and milky pastels. You even can use varnishes as spot colors to give layout elements a different gleam from the rest of the page. Although experienced designers sometimes mix spot colors to produce special shades not otherwise available, it's unlikely that you will need to do so.

Tip ‚

If you create spot colors, I suggest that you include the word Spot as part of the name , so you can quickly tell in a palette or menu whether a selected color will print on its own plate or be color-separated. InDesign does use an icon to tell you whether a color is process or spot, as well as what color model (CMYK, RGB, or LAB) it was defined in (refer to Figure 8-1), but using the word is often more visible than looking for a tiny icon.

Note ‚

Adobe programs, including InDesign, show spot colors like Pantone, Toyo, and DIC as being based on the CMYK color model, even though they're not. It doesn't really matter, because if you print them as a spot color, they get their own plate and your printer will use the actual Pantone, Toyo, or DIC ink. And if you color-separate them into process colors, you'll get the CMYK values shown in the Swatch Options dialog box or by holding the mouse over the color name in the Swatches pane (if the Tool Tips option is enabled in the Preferences dialog box, as described in Chapter 3).

Some designers use both process and spot colors in a document ‚ known as using a fifth color. Typically, the normal color images are color-separated and printed via the four process colors while a special element (such as a logo in metallic ink) is printed in a spot color. The process colors are output on the usual four negatives ; the spot color is output on a separate, fifth negative and printed using a fifth plate, fifth ink roller , and fifth inkwell . You can use more than five colors; you're limited only by your budget and the capabilities of your printing plant.

No matter whether you set a color to be a spot color, you still have the option when you output to convert all spot colors to process (see Chapter 31). What you can't do when printing is select specific spot colors to be output as process colors (be color-separated) and let others remain spot colors. If you're going to color-separate some colors and have others print as spot colors, you must be sure to set them up properly in the Swatch Options dialog box.

InDesign can convert spot colors to process colors, and vice versa. This handy capability lets designers specify the colors they want through a system they're familiar with, such as Pantone, without the added expense of special spot-color inks and extra negatives.

You can convert a color defined in any model to the CMYK, RGB, or LAB models simply by selecting one of those models when editing the color: Just use the Color Mode pop-up menu in the Swatch Options dialog box.

Caution ‚

Colors defined in one model and converted to another may not reproduce exactly the same because the physics underlying each color model differ slightly. Each model was designed for use in a different medium such as paper or a video monitor.

Although conversions are almost never an exact match, there are guidebooks that can show you in advance the color that will be created. With Pantone Process variation (which InDesign supports), designers can pick a Pantone color that will color-separate predictably. And the Focoltone and Trumatch colors were created by mixing process colors, so all can reliably be color-separated into CMYK.

Tip ‚

If you use Pantone colors, I suggest that you get a copy of the Pantone Process Color Imaging Guide: CMYK Edition swatchbook, available from several sources, including art and printing supply stores, mail-order catalogs, and Pantone itself. This swatchbook shows each Pantone color and the CMYK equivalent so that you can see how accurate the conversion will be and, thus, whether you want to use the actual Pantone ink on its own negative or convert to CMYK.