What About Other Kinds of Masking?

Illustrator offers other tools that do some form of masking. Most of those tools are explored in other chapters of this book in detail, but it will be helpful to quickly note them here and explain their relationship to clipping masks.

Opacity masks work like clipping masks except that in addition to clipping a section of an object, they also apply various definable filters or effects. For instance, you can use an opacity mask to both crop a section of a drawing and assign a blue tint to that section of the illustration. Or you can use an opacity mask to crop a section of an illustration and make that section semi-transparent . Chapter 17 explains how to create and apply opacity masks.

Printers crop marks are used to tell printers where to trim (cut) an illustration. You can create printers crop marks by drawing a rectangle over an illustration and selecting Object Crop Area Make, as shown in Figure 13-11.

Figure 13-11: Defining crop marks

Crop marks appear on the printed page and are often included in helpful templates available from print shops for designing CD covers, business cards, postcards, and other designs. You remove crop marks by choosing Object Crop Area Release. Working with print shops is examined in more detail in Chapter 22.

Finally, layers can be used as clipping masks. Chapter 21 explains how to use layers to automate and manage complex illustration procedures.