Data Compression — Summer 2022

Define Data Compression and Data Decompression. Explain their needs in practical applications.

Explain different compression techniques with example.

Explain Modeling and Coding with suitable example.

Define ‘Compression Ratio’ with example.

Write short note on Uniquely Decodable Code (UDC) with example.

Encode the following sequence using LZW algorithm. “wabba$wabba$wabba$wabba$woo$woo$woo”

Given an alphabet A ={a1,a2,a3,a4}, find the first-order entropy in the following cases:

P(a1) = P(a2) = P(a3) = P(a4) = 1/4

P(a1) = 1/2 , P(a2) = 1/4, P(a3) = P(a4) = 1/8

P(a1) = 0.505 , P(a2) = 1/4, P(a3) = 1/8, P(a4) = 0.12

Explain different approaches to build mathematical models.

Write short note on Context Based Compression.

Find minimum variance Huffman code for the alphabet A={a1,a2,a3,a4,a5} where P(a1) = P(a3) = 0.2, P(a2) = 0.4, P(a5) = 0.1.

Write procedure to decode Arithmetic Coding Tag.

What is Golomb Code? Find Golomb code for n=0,1,…,15 and m=5.

Compare and contrast Arithmetic coding and Huffman Coding.

Discuss applications of Huffman Coding.

Define ‘Dictionary’ in dictionary techniques. Write the difference between static and adaptive dictionary schemes.

When Adaptive Huffman coding is required? Discuss ‘Update’ procedure of Adaptive Huffman coding with example.

Write advantages of Vector Quantization over Scalar Quantization.

What is Quantization Problem? Differentiate Uniform and Non-Uniform Quantization.

Describe CALIC with example.

Discuss Diagram Coding with example.

Write short note on JPEG standard.1

How adaptive quantization is different from uniform quantization? Explain two approaches - forward adaptive approach and backward adaptive approach for adapting the quantizer parameter.

Define the term : (i) SNR, (ii) Conditional Entropy

Explain ppm (prediction with partial match) with example.

Discuss LZ77 algorithm and justify – the size of window affects the performance of LZ77 algorithm.