UGC NET CSE | December 2019 | Part 2 | Question: 70

Question

Consider the following statements with respect to approaches to fill area on raster systems:

$P$: To determine the overlap intervals for scan lines that cross the area

$Q$: To start from a given interior position and pain outward from this point until we encounter the specified boundary conditions.

Select the correct answer from the options given below:

• A. $P$ only
• B. $Q$ only
• C. Both $P$ and $Q$
• D. Neither $P$ nor $Q$

Answer 1

Concept:
In raster scan system, electron beam move across the screen one row at a time from top to bottom.
In this, electron beam intensity is turned on and off to produce illumination on the screen.
Explanation:
There are two approaches used in area filling on raster systems: one is scan line algorithm and
another is seed fill algorithm.
1) Scan line algorithm: determine the overlap intervals for scan lines that cross the area or scan
line. A scan line is a line of pixels that are plotted on display device when electron beam scans the
display area horizontally.
2) Seed fill algorithm: It starts from interior position and point outward from this point until the
boundary condition reached. In this, a point is selected and then four or eight connected
approaches is used to fill it.