Page 46 - DCAP504_Computer Graphics

Yadwinder Singh, Lovely Professional University Unit 4: Scan Conversion I

Unit 4: Scan Conversion I

CONTENTS
Objectives
Introduction

4.1 Methods – Analog and Digital
4.2 Line
4.3 Circle
4.4 Ellipse
4.5 Arcs and Sectors
4.6 Summary

4.7 Keywords
4.8 Self Assessment
4.9 Review Questions
4.10 Further Readings

Objectives

After studying this unit, you will be able to:
• Describe different methods of scan conversion
• Explain scan conversion of line, circle, ellipse, arcs and sectors
Introduction

An object is displayed on the computer screen after deciding as to which pixel of the screen needs to be
highlighted. Various patterns are obtained on the computer screen by highlighting the required pixels.
Most of the operators normally think in terms of more complex graphic objects such as cubes, cones,
circles, and ellipses. Several algorithms have been developed to generate such complex graphic objects.
A computer may use different algorithms to produce raster images on raster devices just by turning the
appropriate pixels ON or OFF. The process of representing continuous graphics objects as a collection of
discrete pixels is known as scan conversion or rasterization. Scan conversion or scan rate converting is
the process of altering the vertical or horizontal scan frequency of video signal for different purposes
and applications. The instrument used for scan conversion is known as scan converter.

Did you know? Scan conversion acts as a bridge between TV and computer graphics technology.

This unit examines the procedures followed in drawing complex objects. It also discusses the various
line drawing algorithms like Bresenham line drawing and circle drawing algorithm. This unit also
explains the mathematical and algorithmic aspects of scan conversion.

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