Digital Video and HD, 2nd Edition

6

Raster images in computing

This chapter places video into the context of computing. Images in computing are represented in three forms, depicted schematically in the three rows of Figure 6.1: symbolic image description, raster image, and compressed image.

• A symbolic image description does not directly contain an image, but contains a high-level 2-D or 3-D geometric description of an image, such as its objects and their properties. A two-dimensional image in this form is sometimes called a vector graphic, though its primitive objects are usually much more complex than the straight-line segments suggested by the word vector.

• A raster image enumerates the greyscale or colour content of each pixel directly, in scan-line order. There are four ...