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Balraj Kumar, Lovely Professional University Unit 12: Color and Shading Model

Unit 12: Color and Shading Model

CONTENTS
Objectives
Introduction

12.1 Light and Color
12.2 Phong Model
12.3 Interpolative Shading Methods
12.4 Summary
12.5 Keywords
12.6 Self Assessment

12.7 Review Questions
12.8 Further Readings

Objectives
After studying this unit, you will be able to:

• Discuss about light and color
• Describe the Phong model
• Analyze interpolative shading methods
Introduction

A color in a computer graphic enhances the image by clearly depicting the information and identifying
the features that are unclear in black and white pictures. Color helps you to distinguish between various
elements of a diagram. Color also helps you to read and understand the information in a quick and
accurate manner.
Color is nothing but light. Light is made up of many colors.
We can see the colors of the visual spectrum.

The visual spectrum comprises red, orange, yellow, green, blue, and violet colors. When light falls on
objects, certain wavelengths of light are absorbed by the objects and rest of the wavelengths of light are
reflected back to the viewer. The reflected back wavelengths are perceived as color by the viewers.
In computer graphics, colors should be specified in such a way that the colors are compatible with the
hardware used and also user friendly. These two requirements can also be known as hardware and user
oriented requirements respectively. In general, it is difficult to find a model that meets both the
requirements.
Color can also be used to add more information into the visual message or picture, and thus convey
clear information. It is necessary to examine and define the role of color in various applications to make
use of color in the visualization of ideas, information, or concepts.
Various mathematical models can be used to find out the shading. Each shading model helps to
determine the relation between the surface and the light source. The identification of the relation
between the surface and the light source helps to create a particular shading effect.
This unit discusses about light, different color models, and how colors can be used in graphics
applications. RGB-color model is also discussed which will help you to understand shading models.

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