About bitmap images and vector graphics

About bitmap images and vector graphics

Computer graphics fall into two main categories-bitmap and vector You can work with both types of graphics in Photoshop and ImageReady moreover a Photoshop file

can contain both bitmap and vector data Understanding the difference between the two categories helps as you create edit and import artwork.

Bitmap images Bitmap images-technically called raster images-use a grid of colors known as pixels to represent images Each pixel is assigned a specific location and color value For example a bicycle tire in a bitmap image is made up of a mosaic of pixels in that location. When working with bitmap images you edit pixels rather than objects or shapes. Bitmap images are the most common electronic medium for continuous-tone images, such as photographs or digital paintings because they can represent subtle gradations of shades and color Bitmap images are resolution-dependent-that is they contain a fixed number of pixels As a result they can lose detail and appear jagged if they are scaled

on-screen or if they are printed at a lower resolution than they were created for.

Example of a bitmap image at different levels of magnification

Vector graphics Vector graphics are made up of lines and curves defined by mathe- matical objects called vectors. Vectors describe an image according to its geometric characteristics For example a bicycle tire in a vector graphic is made up of a mathematical definition of a circle drawn with a certain radius set at a specific location and filled with a specific color. You can move resize or change the color of the tire without losing the quality of the graphic.

Vector graphics are resolution-independent-that is they can be scaled to any size and printed at any resolution without losing detail or clarity As a result vector graphics are the best choice for representing bold graphics that must retain crisp lines when scaled to various sizes-for example logos.

Example of a vector graphic at different levels of magnification

Because computer monitors represent images by displaying them on a grid both vector and bitmap data is displayed as pixels on-screen.