To prepare data for display or printing. All data delivered to a screen or printer must be in the form of a matrix of pixels or dots (a bitmap), which is rendered one line at a time. The exception is a vector plotter, which accepts vector images and literally draws with pens (see
vector graphics and
plotter).
The screen bitmaps are created by rasterizing software in the computer or a raster image processor (RIP) chip in the graphics card or printer.
There are generic rasterizing routines as well as routines for specific formats such as PostScript, PDF, vector fonts and vector drawings. Images in native bitmap formats also have to be scaled into screen and printer bitmaps. See
RIP,
raster scan,
font scaler and
host-based printer.