Page 179 - DCAP504_Computer Graphics

Computer Graphics

The study of shading models helps to determine how an object’s surface can be visualized under
various lighting conditions. In addition, the Phong model and interpolative shading model is also
discussed.
12.1 Light and Color
Light is a term used for a range of electromagnetic radiation which a human eye can easily detect. Color
is the visual perceptual property corresponding to the types called red, green, blue and others in
humans. The study of relationship between light and the color should follow an international standard
for the specification and measurement of colors. The study of relationship between light and color also
provides a better understanding of the widely used red, green, and blue (RGB) color model.
Light

Light exhibits dual nature. The reason is that, sometimes light exhibits the characteristics of a particle
and sometimes it exhibits the characteristics of a wave. Perhaps, it is most precise to say that the
concepts of both waves and particles can be used in simplified models that explain the nature of light.
Light is such a complex phenomenon where a single model cannot explain its nature.
Basic Characteristics of Light
As we have mentioned above that the light has the characteristics of both wave and a particle, light is
considered as the narrow frequency band of waves to which human eyes are sensitive. Figure 12.1
depicts spectrum of visible light.

Figure 12.1: Spectrum of Visible Light

Source: http://www.cliffsnotes.com/study_guide/Characteristics-of-Light.topicArticleId-10453,articleId-
10440.html#huetinck3831c05-fig-0001

-9
Did you know? Wavelength of light can be measured in units of nanometers (nm) where 1 nm = 10
meter or it can be measured in terms of angstroms (Å) where 1Å = 10 -10 m).
Light travels at very high speed of about 3 × 108 m/sec. Light can be characterized into following three
terms:

1. Brightness
2. Hue
3. Saturation

172 LOVELY PROFESSIONAL UNIVERSITY