Visual information is the most important information on which the majority of all living organisms base their cognition and survival strategy. A visual scene has two important cognitive categories, which are crucial for image understanding: shapes and materials. This book focuses on the latter category—visual aspects of surface materials which manifest themselves as visual textures. Visual texture is of key importance for recognition of objects as well as for estimation of their properties. Pixels, as the basic elements of any digitized visual texture, are known to be highly spatially, and spectrally correlated, but they are also correlated in the time or viewing and illumination angular spaces. Representations of visual textures which respect these multi-dimensional visual space correlations thus form an advantageous foundation for any advanced visual information processing applied to both cognitive (analysis) and modeling (synthesis) purposes.