Office 2007 Bible

Understanding Raster Graphics

Whether you’re putting together a slide show to display your vacation photos or adding photos of industrial products to a business presentation, PowerPoint has the tools and capabilities you need. And with the new Picture Styles feature in PowerPoint 2007, it has never been easier to give those photos professional-looking frames, shadows, and other effects.

There are two kinds of graphics in the computer world: vector and raster. Vector graphics (clip art, drawn lines and shapes, and so on) are created with mathematical formulas. Some of the advantages of vector graphics are their small file size and the fact that they can be resized without losing any quality. The main disadvantage of a vector graphic is that it doesn’t look “real.” Even when an expert artist draws a vector graphic, you can still tell that it’s a drawing, not a photograph. For example, perhaps you’ve seen the game The Sims? Those characters and objects are 3-D vector graphics. They look pretty good but there’s no way you would mistake them for real people and objects.

In this chapter, you’ll be working with raster graphics. A raster graphic is made up of a very fine grid of individual colored pixels (dots). The grid is sometimes called a bitmap. Each pixel has a unique numeric value representing its color. Figure 24-35 shows a close-up of a raster image. You can create raster graphics from scratch with a “paint” program on a computer, but a more common way to acquire a raster graphic ...