ITPEC FE Morning October 2020 Question 24
Which of the following is a method of improving the appearance of a jagged edge of a slanted line to be smoothed on a screen, such as that of an LCD?
Explanation
Anti-aliasing — blends the pixels along an edge so a slanted line no longer shows a staircase.
A screen is a grid of square pixels, so a slanted line drawn only with fully on or fully off pixels shows steps, called jaggies. Anti-aliasing gives the edge pixels intermediate colours in proportion to how much of each pixel the line covers, and the eye reads the result as a smooth edge.
Answer (a)
Why not others:
- •(b) Bump mapping — perturbs the surface normals so a flat 3D surface looks rough or embossed
- •(c) Shading — colours a 3D surface by its angle to the light to give it depth
- •(d) Texture mapping — wraps a 2D image onto the surface of a 3D model
Key rule: Jagged edges come from sampling at pixel resolution and are fixed by anti-aliasing; bump mapping, shading and texture mapping change how 3D surfaces look.
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