Discrete Wavelet Transformations, 2nd Edition

CHAPTER 3AN INTRODUCTION TO DIGITAL IMAGES

One of the main application areas of wavelet transforms is image processing. Wavelet transforms can be used in processes designed to compress images, search for edges in images, or enhance image features. Since several sections of this book are dedicated to image compression and examples involving images are featured throughout the text, we include this chapter on the basics of digital images.

It is quite tempting to dedicate many pages to the various aspects of image processing. In this chapter we discuss the basic material necessary to successfully navigate through the remainder of the text. If you are interested in more thorough treatments on the numerous topics that comprise digital image processing, I might suggest you start by consulting Russ [79], Gonzalez and Woods [48], Gonzalez, Woods, and Eddins [49], or Wayner [101].

This chapter begins with a section that describes digital grayscale images. We learn how digital images can be interpreted by computer software and how matrices are important tools in image processing applications. We also discuss intensity transformations. These transformations are commonly used to improve the image display. Section 3.2 deals with digital color images as well as some popular color spaces that are useful for image processing. An important step in image compression is that of data encoding. Here the values of the (transformed) image are given new representations with the goal of requiring less space ...