Digital signal processing is ubiquitous. It is an essential ingredient in many of today¿s electronic devices, ranging from medical equipment to weapon systems. It makes the difference between dumb and intelligent systems. This book is organized into five parts: (1) Introduction, which contains an account of Prof. Constantinides¿ contribution to the field and brief summaries of the remaining chapters of this festschrift, (2) Digital Filters and Transforms, which covers efficient digital filtering techniques for improving signal quality, (3) Signal Processing, which provides an insight into fundamental theories, (4) Communications, which deals with some important applications of signal processing techniques, and (5) Finale, which contains a discussion on the impact of digital signal processing on our society and the closing remarks on this festschrift.