02-07-2012, 11:46 AM
Introduction to Computer Graphics
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Introduction
The computer is an information processing machine. It is a tool for storing, manipulating and correlating data. There are many ways to communicate the processed information to the user. The computer graphics is one of the most effective and commonly used way to communicate the processed information to the user. It displays the information in the form of graphics objects such as pictures, charts, graphs and diagrams instead of simple text. Thus we can say that computer graphics makes it possible to express data in pictorial form.
In computer graphics, pictures or graphics objects are presented as a collection of discrete picture elements called pixels. The pixel is the smallest addressable screen element. It is the smallest piece of the display screen which we can control. The control is achieved by setting the intensity and color of the pixel which compose the screen.
Image Processing as Picture Analysis
The computer graphics is a collection, contribution and representation of real or imaginary objects from their computer-based models. Thus we can say that computer graphics concerns the pictorial synthesis of real or imaginary objects. However, the related field image processing or sometimes called picture analysis concerns the analysis of scenes, or the reconstruction of models of 2D or 3D objects from their picture. This is exactly the reverse process.
Representative Uses of Computer Graphics
The use of computer graphics is wide spread. It is used in various areas such as industry, business, government organizations, education, entertainment and most recently the home. Let us discuss the representative uses of computer graphics in brief.
Output Technology
Fig. 1.3 shows the historical development in the output technology. In early days of computer the hardcopy devices such as teletype printer and line printer were in use with computer driven CRT displays. In mid fifties command and control CRT display consoles were introduced. The more display devices developed in mid-sixties and in common use until the mid-eighties, are called vector, stroke, line drawing or calligraphic displays. The term vector is used as a synonyms for line; a stroke is a short line, and characters are made of sequence of such strokes.
Software Technology
Like output and input technology there is a lot of development in the software technology. In early days low level software were available. Over the years software technology moved from low level to device dependent and then to device independent packages. The device independent packages are high level packages with can drive a wide variety of display and printer devices. As a need for the device independent package a standardization is made and specification are decided. The first graphics specification to be officially standardized was GKS (the Graphical Kernel System). GKS supports the grouping of logically related primitives such as lines, polygons, and character strings and their attributes in collected form called segments. In 1988, a 3D extension of GKS, became an official standard, as did a much more sophisticated but even more complex graphics system called PHIGS (Programmer’s Hierarchical Interactive Graphics System).
Summary
Computer graphics is one of the most exiting and rapidly growing computer field. It is also an extremely effective medium for communication between human beings and computers. It is one of the most effective and commonly used way to communicate the processed information to the user. Mainly this unit deals with the image processing as picture analysis, advantages of interactive graphics, representative uses of computers graphics. Classification of applications and development of hardware and software for computer graphics.