Computer Graphics

Computer Graphics

Computer graphics – Is concerned with producing images and animations (or sequences of images) using a computer. This includes the hardware and software systems used to make these images. The field of computer graphics has grown enormously over the past 10–20 years, and many software systems have been developed for generating computer graphics of various sorts. This can include systems for producing 3-dimensional models of the scene to be drawn, the rendering software for drawing the images, and the associated user-interface software and

Types of computer graphics
There are two types of computer graphics
1. Raster and;
2. Vector.
Raster graphics
A raster graphics image or bitmap is a data structure representing a generally rectangular grid of pixels, or points of color, viewable via a monitor, or other display medium. Raster images are stored in image files with varying formats such as;
a) BMP (windows bitmap),
b) TIF (Tagged Image file format),
c) GIF (Graphics Interchange format),
d) JPG (Joint Photographic group),
e) PNG (Portable Network Graphics) e.t.c
A bitmap is technically characterized by the width and height of the image in pixels and by the number of bits per pixel.
Vector graphics
Vector graphics uses geometrical primitives such as points, lines, curves, and polygon(s), based on mathematical equations, to represent an image. In Windows platform WMF (Windows Metafile format) is most widely used vector graphic format supported many printers.

Definitions of Key terms
i) Pixel
A pixel (or picture element) is a single point in a raster image. Pixels are normally arranged in a regular 2-dimensional grid, and are often represented using dots or squares. The intensity of each pixel is variable; in color systems, each pixel has typically three components such as red, green,
and blue.
ii) Rendering
Rendering is the process of generating an image from a model (or models in what collectively could be called a scene file), by means of computer programs. A scene file contains objects in a strictly defined language or data structure.
iii) 3D projection
3D projection is a method of mapping three dimensional points to a two dimensional plane. As most current methods for displaying graphical data are based on planar two dimensional media, the use of this type of projection is widespread, especially in computer graphics, engineering and
iv) Ray tracing
Ray tracing is a technique for generating an image by tracing the path of light through pixels in an image plane. The technique is capable of producing a very high degree of photorealism.
v) Shading
Shading refers to depicting depth in 3D models or illustrations by varying levels of darkness. It is a process used in drawing for depicting levels of darkness on paper by applying media more densely or with a darker shade for darker areas, and less densely or with a lighter shade for lighter areas.
vi) Texture mapping

Texture mapping is a method for adding detail, surface texture, or colour to a computer generated graphic or 3D model. A texture map is applied (mapped) to the surface of a shape, or polygon.
vii) Volume rendering
Volume rendering is a technique used to display a 2D projection of a 3D discretely sampled data set.
viii) 3D modeling
3D modeling is the process of developing a mathematical, wireframe representation of any three dimensional object, called a 3D model via specialized software.
ix) Ant-aliasing
In computer graphics, antialiasing is a software technique for diminishing jaggies (stairstep-like lines) that should be smooth. Jaggies occur because the output device, the monitor or printer, doesn’t have a high enough resolution to represent a smooth line. Antialiasing reduces the prominence of jaggies by surrounding the stairsteps with intermediate shades of gray (for gray-scaling devices) or color (for color devices).
Application of Computer Graphics
i) Computer-Aided Design for engineering and architectural systems etc.

Objects maybe displayed in a wireframe outline form. Multi-window environment is also favored for producing various zooming scales and views. Animations are useful for testing performance.
ii) Presentation Graphics
To produce illustrations which summarize various kinds of data. Except 2D, 3D graphics are good tools for reporting more complex data.
iii) Computer Art

Painting packages are available. With cordless, pressure-sensitive stylus, artists can produce electronic paintings which simulate different brush strokes, brush widths, and colors. Photorealistic techniques, morphing and animations are very useful in commercial art.
iv) Entertainment
Used to produce motion pictures, music videos, TV shows and Computer games
v) Education and Training
Used for training with computer-generated models of specialized systems such as the training of ship captains and aircraft pilots.
vi) Visualization
Used for analyzing scientific, engineering, medical and business data or behavior. Converting data to visual form can help to understand mass volume of data very efficiently.
vii) Image Processing
Image processing is to apply techniques to modify or interpret existing pictures. It is widely used in medical applications.
viii) Graphical User Interface
Multiple window, icons, menus allow a computer setup to be utilized more efficiently.

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