Chapter 1 - Introduction

Abstract

With the rapid development of digital image processing techniques and the popularization of the Internet, digital images are being used more and more widely in a number of applications from medical imaging and law enforcement to banking and daily consumer use. They are much more convenient in editing, copying, storing, transmitting, and utilizing. However, unfortunately, at the same time, digital images are facing the problems of copyright protection and content authentication. Since the 1990s, the development of information hiding techniques has provided a way to protect digital media. Such techniques embed some secret information like private annotations, business logos, and critical intelligence into cover media in an invisible form so that many applications, like ownership claim of digital contents, copyright protection of media, and covert communication between parties, can be fulfilled. In general, compared with the cover media, the stego media has a small amount of content distortion that is usually imperceptible to human vision. However, such distortion is not preferred in some applications, such as legal documentation, medical imaging, military reconnaissance, and high-precision scientific investigation, because it may lead to risks of incorrect decision making. In view of this, a kind of novel information hiding technique, which is referred to as reversible, invertible, lossless, or distortion-free information hiding, has been developed in recent years. Lossless information hiding techniques can be employed to restore stego images to their pristine states after the hidden data are extracted. In this chapter, we first introduce the background of this book, including the concepts and issues related to images and network information security. Then, we introduce the concepts, models, research branches, and required properties of information hiding; the classification of information hiding algorithms; and the application fields of information hiding techniques. Then, an overview is provided of the coding techniques for image compression, including entropy coding, transform coding, vector quantization, and block truncation coding, together with JPEG and JPEG2000 standards. Next, we provide an overview of the information hiding techniques for images, including the framework, classification, and required properties. Thereafter, we introduce the possible applications of lossless information hiding techniques for images. Finally, we give the outline of this book.