CS559 Midterm
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CS559 Midterm Exam
November 1, 2006
This exam is closed book and closed notes.
You will have the entire period (until 9:00pm) to complete the exam, although the exam
is designed to take less time.
Please write your name and CS login on every page!
Write numerical answers in fractional form or use radicals (square root symbols) – we
would prefer to see
than .866. You should not need a calculator for this exam.
Unless otherwise noted, assume that everything is a righthanded coordinate system and
that angles are measured counter clockwise. E.g. to find the direction of rotation, point
your thumb along the axis and curl your fingers.
If you need extra space, use the back of a page, but clearly mark what everything is. We
may look at your work to determine partial credit.
For the short answer questions, concise answers will be rewarded. One or two sentences
should do the trick.
Note: there are only 70 points on this exam (not 100).
Total: ___ / 70
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Question 1: (4 Points)
Define
metamer
(in the sense used in graphics – it has another meaning in chemisty):
Metamers are colors that are perceptually indistinguishable.
Two different distributions of light that cause the same sensor response.
Question 2: (4 Points)
If Lightness is linearly coded between 0 and 255, is the difference between 100 and 101,
or the difference between 200 and 201 more noticeable (perceptually)? Explain your
answer.
100 to 101 – it’s a 1% difference (while 200 to 201 is a .5% difference, and
since the eye sees relative differences that’s what matters)
Question 3: (8 Points)
A quadratic Bezier curve in 2D has its control points at (0,0), (6,6), and (12,0).
What are the control points for an identical
cubic
Bezier curve?
(0,0), (4,4), (8,4), (12,0)
to match the derivatives, remember that the scaling factor for Beziers is
the degree, so:
2(P1P0) (for points on the quadratic) = 3(P1P0) (for points on the cubic)
Question 4: (5 Points)
Which of the following things are artifacts from aliasing?
Note: there might be several things that are aliasing, so mark each one as either “A” for
aliasing or “N” (for not).
_
N
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 Spring '08
 LiZhang
 Cartesian Coordinate System, Digital camera, cs login

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