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Anil Sharma, Lovely Professional University Unit 11: Compression

Unit 11: Compression notes

Contents
Objectives
Introduction
11.1 CODEC
11.2 Compression Quality
11.3 Types of Compression
11.3.1 Lossless Compression Algorithms
11.3.2 Lossy Compression Algorithms
11.4 Redundancies and its Types
11.4.1 Coding Redundancy
11.4.2 Interpixel Redundancy
11.4.3 Psychovisual Redundancy
11.5 Image Compression Models
11.5.1 The Source Encoder and Decoder
11.5.2 The Channel Encoder and Decoder
11.6 Summary
11.7 Keywords
11.8 Review Questions
11.9 Further Readings

objectives

After studying this unit, you will be able to:
• Understand codec
• Explain compression quality
• Describe compression quality
• Understand redundancies and its types
• Explain image compression models

introduction

Multimedia compression is employing tools and techniques in order to reduce the file size of
various media formats. With the development of World Wide Web the importance of compress
algorithm was highlighted because it performs faster in networks due to its highly reduced file size.
Furthermore with the popularity of voice and video conferencing over the Internet, compression
method for multimedia has reached it next generation to provide smooth service even in unreliable
network infrastructure. Although many methods are used for this purpose, in general, these
methods can be divided into two broad categories named Lossless and Lossy methods.

11.1 CoDeC

The “Codec” is a technical name for “compression/decompression”. It also stands for
“compressor/decompressor” and “code/decode”. All of these variations mean the same thing:

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