Section V: Image Compression

Chapters List

1 Introduction

The goal of lossless image compression is to represent an image signal with the smallest possible number of bits without loss of any information, thereby speeding up transmission and minimizing storage requirements. The number of bits representing the signal is typically expressed as an average bit-rate (average number of bits per sample for still images, and average number of bits per second for video). The goal of lossy compression is to achieve the best possible fidelity given an available communication or storage bit-rate capacity, or to minimize the number of bits representing the image signal subject to some allowable loss of information. In this way, a much greater reduction in bit-rate can be attained as compared to lossless compression, which is necessary for enabling many real-time applications involving the handling and transmission of audiovisual information. The function of compression is often referred to as coding, for short.

Coding techniques are crucial for the effective transmission or storage of data-intensive visual information. In fact, a single uncompressed color image or video frame with a medium resolution of 500 500 pixels would require 100 seconds for transmission...