Chapter 4. Vector Files

In this chapter we'll be talking about vector files. Because we've already introduced bitmap files in Chapter 3, Bitmap Files, we'll be contrasting selected features of vector files with their bitmap counterparts.

Contents:
Vector Versus Bitmap Files
What Is Vector Data?
Vector Files and Device Independence
Sources of Vector Format Files
How Vector Files Are Organized
Vector File Size Issues
Scaling Vector Files
Text in Vector Files
Pros and Cons of Vector Files

Vector Versus Bitmap Files

A bitmap file in some sense contains an exact pixel-by-pixel mapping of an image, which can then be reconstructed by a rendering application on the display surface of an output device. Rendering applications seldom have to take into account any structural elements other than pixels, scan lines, strips, and tiles--subdivisions of the image which were made without reference to the content of the image.

Vector files contain, instead, mathematical descriptions of one or more image elements, which are used by the rendering application to construct a final image. Vector files are thus said to be made up of descriptions of image elements or objects, rather than pixel values. Although the term object has a modern meaning, you will find vector format specifications adhering to the older usage.