Get Your Hands Around Illustrator s Curves

Adobe Illustrator is often compared and contrasted to its graphical sibling, Adobe Photoshop. Photoshop allows artists to create or edit illustrations by defining and editing individual pixels. A pixel (from picture element ) is the tiny dot that is the smallest element of a graphical object. A file that records the location, color , and quality of a bunch of pixels is called a bitmap or raster file , and images generated using pixel editing software are called bitmap or raster images .

Vector-based graphics are quite different. Adobe Illustrator is the most widely used vector art program, but others include Macromedia Freehand and CorelDRAW. Macromedia Flash is also based on vector graphics. Other graphical software options, such as Macromedia Fireworks, are hybrid programs that combine both vector and pixel editing tools.

Figure 1-1 shows a bitmap image in Adobe Photoshop. When you examine it in detail, you can see that the illustration is composed of thousands of pixels ”each one individually colored and defined.

Figure 1-1: Zoomed in, the hand is revealed to be composed of identically sized square pixels with a different color assigned to each pixel.

By contrast, vector art is defined by line segments that are controlled by anchor points. The enlarged section of the illustration in Figure 1-2 shows that the birds in the drawing are defined not by individual pixels but by many curved lines.

Figure 1-2: Each bird, and each element in each bird, is defined by a set of curves.

To break this down a bit, vector magnitude incorporates elements such as length, outline color, outline thickness , and fills. Vector direction means that the lines go from point A to point B, although not necessarily in a straight line.

Vector art is scalable. The files you create in Illustrator can be printed on a postage stamp, a business card, a full-sized poster, or a billboard over Sunset Strip without losing quality or even increasing in file size ! For example, the Illustrator file in Figure 1-3 was used to create both a postcard and full-sized framed posters for exhibit in galleries.

Figure 1-3: Illustrator artwork is scalable ”with no loss in resolution, and no increase in file size.

Understand Paths, Anchor Points, and Fills

Each version of Adobe Illustrator has piled on new tools, effects, and techniques for manipulating curves and fills. Illustrator s tool kit can be pretty overwhelming to new users, part-time users, and even long-time graphic design professionals who are upgrading.

The key thing to keep in mind is that all the tools in Illustrator essentially manipulate paths, anchor points, and fills. Paths are lines, which can be straight or curved. Closed paths are objects such as circles or stars, in which the start and end of the path are the same point. Open path objects do not have the same start and end points. Figure 1-4 shows both an open and a closed path.

Figure 1-4: On the top is an open path, and on the bottom is a closed path. Each path has three anchor points.

Anchor points are the start and end points in a path (line), as well as other points along the path that control the direction and curvature of that path. The paths in Figure 1-4 each have three anchor points.

Note	To get a bit Zen about the whole process of working in Illustrator you will go down many paths as you create artwork. But at the heart of every object in Illustrator, you'll find anchors and paths.

Paths can have fills, or not. Much of this book will be devoted to exploring various fill options, and how to apply them. But if you keep in mind that all Illustrator objects essentially boil down to paths and fills, the complex set of features will at least make sense.

Use Illustrator with Other Programs

Many complex illustrations mix both bitmap and vector art. Illustrator can incorporate bitmaps into illustrations, and provides some rudimentary editing features for bitmaps. But in general, you (or a collaborator) will create bitmaps in a program such as Adobe Photoshop and bring them into Illustrator in a basically finished state.

Artwork produced in Illustrator is ultimately destined for either a digital display device (such as a monitor or digital projection screen) or some form of hardcopy (such as a poster, framed art, or a picture in a book, magazine, or brochure). Sometimes entire projects are created and printed directly from Illustrator, but most Illustrator artwork ends up in another software program. Artwork destined for the Web will likely be managed through programs such as Macromedia Dreamweaver, Microsoft FrontPage, or Adobe s own GoLive web design software. Illustrations destined for print will likely be integrated into a publication using desktop publishing programs.

Illustrator drawings can be easily integrated into desktop publishing programs such as Adobe PageMaker, Adobe InDesign, and QuarkXPress. These programs, and others, support Illustrator s native AI file format, and even more programs support Illustrator s EPS file format that preserves the features of your illustration for export.

Caution

Presenting Illustrator artwork on the Web is a bit of a challenge because native mainstream browser support for images is limited to bitmap file formats such as JPEG and GIF. Additional formats require plug-ins. However, Illustrator provides extremely powerful and easy-to-use export-to-web tools that make it easy to convert your Illustrator vectors to web-compatible bitmaps.