Course: CIS451/651 Data Compression
in Multimedia
Professor: Paul D. Amer
Semester: Spring 2009
Title: Homework Chapter 4 - Arithmetic Coding
Due Date:
Tasks
Read Sections 4.1 - 4.4.2, and 4.5-4.7, inclusive. (You are not responsible
for Section 4.4.3, nor the details within Section 4.6). For all problems
where the answer requests any value within an interval, choose the midpoint or a greater value
that is easy to convert to binary.
For all answers, show all work.
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(2 pts) Chapter 4 Projects and Problems: 5
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also convert your real tag answer to binary
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(2 pts) Chapter 4 Projects and Problems: 6
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(4 pts) Assume a 2 symbol input alphabet (a1, a2}
with probabilities {.6, .4}, respectively. Use arithmetic encoding
(without scaling) to derive a binary encoding of the
following two strings:
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a1 a1 a2
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a2 a2 a2
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(2 pts) Given an alphabet {a,b,c,d} with respective expected probabilities
{.1,.3,.4.,.2}, decode the value .75 as a 8 symbol string.
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(2 pts) Encoding without scaling. Redo Example 4.3.5 (which
is based on Example 3.2.3), but with underlying probabilites for {a1,
a2, a3} of {.7, .1, .2} instead of {.8, .02, .18}.
Submit your answer in binary.
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(2 pts) Decoding without scaling. Redo Example 4.3.6 with your previous
answer (and revised probabilities {.7,.1,.2}).
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(2 pts) Encoding with scaling. Redo Examples 4.4.2 also with
the revised probabilites of {.7, .1, .2}.
- Submit your answer in binary.
- Only apply scaling rules E1and E2, not E3.
- In example 4.4.2, the first calculation of u(3) - "(0.8 - 0.312)" should say "(0.6 - 0.312)"
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(2 pts) Decoding with scaling. Redo Example 4.4.3 with your previous
answer (and revised probabilities of {.7, .1, .2}).
- Only apply scaling rules E1and E2 , not E3.
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In decoding with scaling, the wordsize technically must be
recomputed at each iteration. For simplicity, use a word size of
6 bits for this problem.
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In example 4.4.3, the first calculation of u(3) - "(0.8
- 0.312)" should say "(0.6 - 0.312)"
Notes
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Students may work individually or in groups of 2.
- Students
in different groups may NOT compare answers prior to submission of their
answers. See the syllabus for the full policy on late submissions
and academic honesty.