Dictionary of Computers - computer graphics

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Use of computers to display and manipulate information in pictorial form. Input may be achieved by scanning an image, by drawing with a mouse or stylus on a graphics tablet, or by drawing directly on the screen with a light pen.

The output may be as simple as a pie chart, or as complex as an animated sequence in a science fiction film, or a seemingly three-dimensional engineering blueprint. The drawing is stored in the computer as raster graphics or vector graphics.

Vector graphics are stored in the computer memory by using geometric formulae. They can be transformed (enlarged, rotated, stretched, and so on) without loss of picture resolution. It is also possible to select and transform any of the components of a vector-graphics display because each is separately defined in the computer memory. In these respects vector graphics are superior to raster graphics. They are typically used for drawing applications, allowing the user to create and modify technical diagrams such as designs for houses or cars.

Raster graphics are stored in the computer memory by using a map to record data (such as colour and intensity) for every pixel that makes up the image. When transformed (enlarged, rotated, stretched, and so on), raster graphics become ragged and suffer loss of picture resolution, unlike vector graphics. They are typically used for painting applications, which allow the user to create artwork on a computer screen much as if they were painting on paper or canvas.

Computer graphics are used in computer-aided design (CAD), and to generate models and simulations in education, engineering, meteorology, medicine and surgery, and other fields of science.

Developments in software mean that designers on opposite sides of the world are able to work on complex three-dimensional computer models using ordinary personal computers (PCs) linked by the Internet rather than powerful graphics workstations.

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