Wikipedia:Simple talk/Archive 14 Computer graphics
I think the article needs extending. Raster images use a set of bitmaps. For an image of a size 300x300, there is a grid of that size. At each position in the grid, there is the color of the dot at that position. It does of course scale much less than vector graphics which use vectors to represent the data. Raster images are used for example when printing something. In the case of GDI, this is done by the printer driver in the computer.