Preface This book analyzes the visual hints by which both humans and computer programs generally interpret, process, and exploit images. The chapters in this book provide a unified framework in which both biological and artificial vision are discussed through visual cues, the role of contexts, and the available multichannels with which information is delivered. These various subjects are traditionally investigated within different scientific communities producing specific technical literature. The exponential explosion of images and videos concerns everybody because media are now present everywhere and in all human activities. At this stage, it seems important that scientists, artists, and engineers in all fields be aware of how images are essential information carriers. Images carry a strong evocative power because they quickly bring to mind a number of related pictures of past experiences--or even abstract concepts like pleasure, attraction, or aversion. Analyzing the impact that images have on people is the thread of this book. It puts forward the connection between technical issues that can be extracted from objec- tive measurements and psychological issues that emerge from perception, bound to the context and the time at which such images are observed. In short, the book