Page 68 - DCAP504_Computer Graphics

Unit 5: Scan Conversion II

The figure 5.8(b) depicts the effect of anti-aliasing.

Figure 5.8 (b): Effect of Anti-aliasing

Now look closely at the two letters shown in figure 5.8 (b). You can still tell that the letter on the left is
jagged but the letter on the right looks a lot smoother. It is very important to know that the image has
been shrunk down back to normal size and it is not been altered in any other way. Therefore, it is
understood that anti-aliasing brings a much more pleasing image to the eye.
5.5 Summary

• A polygon is a closed 2D object or figure that has three or more sides.
• The process of coloring the object or image area or region is called region filling.
• A glyph can be a numeric, alphabetic font or some other symbol that pictures an encoded
character.
• The characteristics of the glyph are always data driven such as size, color, orientation.
• Aliasing refers to an effect that causes different signals to become indistinguishable at the time of
sampling signals.

• Anti-aliasing is a method of deceiving the eye where a jagged edge is shown as a smooth end.
5.6 Keywords
Coherence: This is the quality when all the parts are clearly connected.
Contour: This is the outline of a figure, body or mass.
Intrinsic: This is an inherent property of a system or a material itself.

Jagged: This is the state of an object marked by irregular projections on the edge or surface.
5.7 Self Assessment
1. State whether the following statements are true or false:

(a) The process of aliasing involves altering the picture’s data rate information and then
inserting the new picture within appropriate synchronization signals.
(b) A polygon is a closed 3D object or figure that has three or more sides.
(c) Cluster of polygons is used to represent closed contours.
2. Fill in the blanks:

(a) ………… refers to an effect that causes different signals to become indistinguishable at the
time of sampling signals.
(b) The algorithm used to define the interior-defined region of a polygon is called ……………
(c) A ………… is nothing but a symbol or a graphical symbol that provides a form of a
character.
(d) ……………….. is often used in games and on graphics cards.

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