Color image processing has gained more importance in recent years because color provides more information than basic gray levels. This information is very rich and can be used not only to represent the scene, but also to analyze it in a better way. In the early days, color image processing was considered a simple extension of gray-level image processing, accomplished by applying the methods used in a single information channel to a three-color representation. However, it was quickly realized that this approach is not useful for many applications because color has its own characteristics. Since then, research on color image processing has been carried out in two ways: focusing on the physics and perception of color, and developing color-specific algorithms.

This book collects a variety of perspectives on color image processing to give an overall picture of the state of art. The first chapter describes the fundamental understanding of color by means of physics and perception of color. The second chapter discusses colorimetry and presents a color appearance model based on viewing conditions and chromatic adaptation transforms. In this regard, CIECAM02-based color spaces are described in detail. Chapter 3 introduces color-difference evaluation, which formularizes perceptual color differences using instrumental color measurements. This topic reveals the relationship between visual and computer color differences, which is essential to develop methods for the analysis and understanding of scenes using color images. The problem of color reproduction is covered in chapter 4. Different devices have different characteristics when reproducing colors, which causes problems in color inconsistency. The authors introduce cross-media color reproduction and color management systems, and then provide details on device colorimetric characterization through numerical and physical models. These help to reproduce consistent colors in a range of different displaying and printing devices.

Chapter 5 explores a process for filtering color images using dihedral group representations. This chapter defines a steerable filter system that provides a transform domain for image classification. The theory behind this filtering system is explained clearly and illustrated with a practical application. Chapter 6 considers Clifford algebra and quaternions in color image processing. It defines the concept of quaternions and describes the use of Clifford algebra for color transform and spatial filtering, with practical examples. The authors include an exhaustive mathematical background for quaternionic and Clifford Fourier transforms. Chapter 7 is devoted to a discussion of the image super-resolution problem and the state of art in this area.

One of the longest contributions is chapter 8, which considers color image segmentation. Covering all approaches to this topic could produce a large book in itself. I appreciate the authors’ efforts to summarize different approaches, including color distribution, color texture and fractal features, watersheds, the J measure-based segmentation (JSEG) method, active contours, and graph-based approaches. Performance evaluation of color image segmentation is also included in this chapter. Chapter 9 explores stochastic modeling for color image segmentation, with a discussion of multichannel Gaussian Markov random fields and multivariate Gaussian mixture models. Color object recognition based on color invariants is introduced in chapter 10, including different color invariants and object detection based on these invariants.

Chapter 11 covers motion estimation in color image sequences. The chapter mainly includes optical-flow-based motion estimation. The interesting topic of protecting color images using encryption is addressed in chapter 12. Chapter 13 discusses the quality assessment of still images, including subjective and objective measures. The last two chapters concern practical uses of color imaging in fine art paintings and electronic endoscopes.

This book covers important topics in color imaging. I recommend it to researchers in the field, as well as research students whose projects involve color image processing.