GTU BE 8th Semester 181602 Data Compression Summer 2018 Question Paper

1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE – SEMESTER ?VIII (old) – EXAMINATION ? SUMMER 2018
Subject Code:181602 Date:30/04/2018
Subject Name:Data Compression
Time:10:30 AM to 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1 (a) What is data compression? Differentiate between lossy and lossless compression
technique? Explain data compression and reconstruction with suitable diagram.
07
(b) Explain data compression = Modeling + coding 07

Q.2 (a) Define self information, Entropy and Average length of code. State the equations
to calculate self information, Entropy and Average length of code. What is their
significance?
07
(b) Explain statistical and dictionary based modeling techniques 07
OR
(b) Explain Shannon-Fano compression technique with following information.
Calculate how many bits are required for below listed symbol and compare it
with ASCII code
symbol D C B F A E
count 10 20 21 3 39 7
07

Q.3 (a) What do you mean by uniquely decodable code? Determine whether following
codes are uniquely decodable or not. (i) {0,01,11,111} (ii) {0,01,110,111} (iii) {1,10,110,111}
07
(b) Explain minimum variance Huffman code? Explain its application over simple
Huffman code.
07
OR
Q.3 (a) Design a Huffman code for source with alphabet set {a1,a2,a3,a4,a5} with
p(a1)=P(a3)=0.2, P(a2)=0.4 P(a4)=P(a5)=0.1 Also find entropy, average length,
and redundancy for this source.
07
(b) Explain how size of window affects the performance of LZ77 algorithm. 07

Q.4 (a) Explain adaptive Huffman encoding and update procedure? 07
(b) Explain LZ77 algorithm and state is drawbacks. 07
OR
Q.4 (a) Explain arithmetic coding encryption and decryption algorithm. List advantage
of this compression technique?
07
(b) Why LZ77 and LZSS are called greedy algorithm? 07

Q.5 (a) Write a Short note on silence compression 07
(b) Explain JPEG image compression technique. What is the significance of DCT
and Quantization in JPEG compression?
07
OR
Q.5 (a) Write a Short note on sampling and Quantization
07
(b) Explain the parameters used to evaluate the performance of compression
algorithm
07
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