About bitmap images and vector graphics

Before working with vector shapes and vector paths, it’s important that you understand the basic differences between the two main categories of computer graphics: bitmap images and vector graphics. You can use Photoshop or ImageReady to work with either type of graphics; moreover, in Photoshop you can combine both bitmap and vector data in an individual Photoshop image file.

Bitmap images, technically called raster images, are based on a grid of colors known as pixels. Each pixel is assigned a specific location and color value. In working with bitmap images, you edit groups of pixels rather than objects or shapes. Because bitmap graphics can represent subtle gradations of shade and color, they are appropriate for continuous-tone images such as photographs or artwork created in painting programs. A disadvan-tage of bitmap graphics is that they contain a fixed number of pixels. As a result, they can lose detail and appear jagged when scaled up on-screen or if they are printed at a lower resolution than that for which they were created.

Vector graphics are made up of lines and curves defined by mathematical objects called vectors. These graphics retain their crispness whether they are moved, resized, or have their color changed. Vector graphics are appropriate for illustrations, type, and graphics such as logos that may be scaled to different sizes.

Logo drawn as vector art

Logo rasterized as bitmap art