Which of the following is/are side effects of scan conversion ? a. Aliasing b. Unequal intensity of diagonal lines c. Overstriking in photographic applications d. Local or Global aliasing
a, b, c and d
Scan conversion maps a continuous primitive (line, circle, polygon) onto a discrete grid of pixels. Because positions are rounded to whole pixels and every pixel has a fixed size, several unwanted side effects appear.
a. Aliasing — the staircase or jagged appearance of edges caused by undersampling a continuous shape; a side effect.
b. Unequal intensity of diagonal lines — a diagonal line drawn with the same number of pixels as a horizontal line of equal x-extent is about √2 times longer, so its pixels are spread thinner and it looks dimmer; a side effect.
c. Overstriking — the same pixel is written more than once (for example where segments meet); on photographic or film output each extra exposure darkens the spot, so it is a side effect.
d. Local or global aliasing — aliasing appears locally as jaggies on edges and globally as moiré or distorted patterns when small repeated objects are sampled; a side effect.
All four listed effects therefore arise from scan conversion, so any choice that leaves out b, c or d is incomplete.
a, b, c and d option is correct.
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