Exam number 1:
There are four questions, 25 points per question. Give a
brief and clear answer.
1. Assume a graphics board with 8 bit per pixel and a
color lookup table. Given an image with 24 bits per
pixel, how can one display the image with a reasonable
visual quality? Describe in few words what is the
process of choosing the best colors for the lookup
table and how to set the pixel colors in the displayed
image.
2. In the Mid-point line algorithm the update of the
decision variable requires one addition in each
incremental step. Why drawing a circle requires two
additions? Can it be done with only one?
3. Define the following terms in two sentences each:
(a) dithering
(b) rigid transformation (Also give an example such
transformation)
(c) affine transformation (Also give an example such
transformation)
(d) oblique projection
(e) specular reflection
(f) ambient light
(g) smooth shading
(h) z-buffer
(i) image-space algorithm
(j) fixed-point (in the context of geometric
transformations)
4. Given two rectangular windows, which may overlap.
Given a line segment, we need to clip the line against
the overlapping rectangle. How the Cyrus-Beck
(parametric) line-clipping algorithm can be extended
to deal with the above problem? Note that the two
windows might not intersect at all.