Page 67 - DCAP504_Computer Graphics

Computer Graphics

If the centre of the pixel is used to determine the attributes then the entire pixel would exhibit those
attributes of the small objects as shown in Figure 5.7 (a). However, Figure 5.7 (b) illustrates pixels object
that would be ignored or lost (long or thin objects ignored), particularly in an animation sequence.

Figure 5.7 (a): Aliasing Effect on a Small Object

Source: Computer Graphics, Second Edition, MALAY K, PAKHIRA , Chapter 9

Figure 5.7 (b): Aliasing Effect in Animation

Source: Computer Graphics, Second Edition, MALAY K, PAKHIRA , Chapter 9
Anti-aliasing

Anti-aliasing is a method of deceiving the eye where a jagged edge is shown as a smooth end. Anti-
aliasing is often used in games and on graphics cards. Especially, in games the ability to smoothen the
edges of images goes a long way in creating a realistic 3D image on the screen. However, it is important
to know that anti-aliasing actually does not smooth out any edges of the images as it merely deceives
the eye. Let us refer to figure 5.8 (a) as an example to demonstrate the effects of anti-aliasing.

Figure 5.8 (a): Effect of Anti-aliasing

In figure 5.8 (a), the letter on the left is blown up and it is without any anti-aliasing. The letter on the
right has anti-aliasing applied to it. In the blown up form it looks like it is simply blurred but if the size
is reduced you may see the difference as shown in figure 5.8 (b).

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