What is Computer Graphics?


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The principles and applications of computer graphics are discussed.

Introduction to Computer Graphics

Computer graphics are related to all activities were static and animated pictures and images are created, processed and manipulated using specialized hardware and computer software. Data in the form of images is easy to understand and interpret. Hence the use of computers in producing static and animated images has revolutionized video games and movies production.

Manipulating images needs powerful tools that have to process and store large amount of data. Computers offer both advantages of very high speed of operations and large capacity of data storage hence their widespread use in generating and processing graphics.

A typical graphics system includes a computer with a fast processor, large memory, frame buffer and a display device such a monitor, an input device such as keyboard and a mouse, an output device such a printer.

Raster and Vector Images

A raster or bitmap image uses a grid of individual dots called pixels where each pixel is a small colored square. When an image is scanned, the image is converted to a collection of pixels called a raster image. This conversion make it easy to edit and process these images. JPEG and GIF images are examples of raster images.

Images in vector graphics are basically points connected by lines of various shapes. Two points and a straight path between them, for example, are used to describe a segment AB but more points and more complex paths are needed for more complicated shapes. Figure 1 below shows the same shape as raster and vector images.

Raster and Vector Images.

Fig. 1 - Raster and Vector Images

Applications Computer Graphics

Computer graphics are applied in industry, art, entertainment, education, medicine and defense. Computer graphics applications may be classified into 4 major groups: user interface, display of information, Design and simulation.

More specific applications include

  • Plotting data for visualization: Pie charts, 2-D and 3-D graphs to show trends, etc.

  • Entertainment: Making movies, games, TV, etc.

  • Simulation is used in engineering, science, medicine, etc. with animation order to explain a process or even a concept. Flight simulators, car racing, etc. are examples of simulation.

  • GUI (Graphical User Interface) design for the computer user to interact with a software for example. Menus, icons, dialog boxes, pull down menu, scroll bar, etc. are examples of GUI.

  • CAD-CAM(electronic circuits design, industrial engineering, ...)

  • Cartography (maps,...)

  • Multimedia

  • Large industrial process monitoring

  • Satellite imaging

  • Technical drawing

Compilers for Computer Graphics

Some of the compilers (languages) that provide their graphical libraries in order to make programming of 2-D and 3-D computer graphics with animation are: Java, Visual C/C++, visual basic, Turbo C, etc.

Basic (primitive) Shapes Computer Graphics

The basic (or primitive) shapes from which almost any shape can be drawn are:

  • segments (defined by two points)

  • arcs (including ellipses)

  • texts

  • raster images (in digital format) that can be processed.

Sub Topics in Computer Graphics

There are 3 basic operations involved in creating a computer graphics of an object:

  • Modeling the shapes: The shape of the object is defined.

  • Rendering: Light, shadows and reflections are put into the shape of the object so that it becomes more realistic.

  • Animation: Describe how the object moves in time and space.

References and Books

1 - Computer Graphics: Principles and Practice in C (2nd Edition) 2nd Edition - James D. Foley
ISBN-13: 978-0201848403

2 - Computer Graphics: Principles and Practice (3rd Edition) 3rd Edition - by John F. Hughes
ISBN-13: 078-5342399523

3 - Computer Graphics - C version - D. Hearn and M. P. Baker; Pearson Education 2004.

4 - 3D Computer Graphics: A Mathematical Introduction with OpenGL 1st Edition - by Samuel R. Buss