Question

Which algorithm is used to generate an ellipse by taking advantage of its symmetry?

• A. Flood-Fill Algorithm
• B. Cohen-Sutherland Algorithm
• C. Midpoint Ellipse Algorithm
• D. Bresenham's Line Algorithm

Hint:

Which of the four is actually an ellipse-drawing algorithm rather than a line, clipping, or fill routine?

Answer 1

The Correct Option is C

First discard what does not draw ellipses. Flood-Fill colours regions, Cohen-Sutherland clips lines against a window, and Bresenham handles straight lines. Only one option is an ellipse generator.

The Midpoint Ellipse Algorithm exploits four-way symmetry: a point $(x, y)$ implies $(-x, y)$, $(x, -y)$, and $(-x, -y)$ about the centre.

\[ (x, y) \Rightarrow (\pm x, \pm y) \]

So it only needs to trace one quadrant and reflects the results, using a decision parameter to pick the next pixel. That symmetry use is precisely what the question describes.

\[\boxed{\text{Midpoint Ellipse Algorithm}}\]