Motivation
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 mat
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Motivation
Abstract 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.
1.1 Visual Texture Definition The notion of texture comes from Latin word texere which means to weave; and textura is a weaving, web, structure. Its meaning may, according to Oxford or Webster’s dictionaries, be any of these: • The process or art of weaving; the fabricating or composing of schemes, writings, etc. A woven fabric, or any natural structure having an appearance or consistence as if woven. • The character of a textile fabric (fine, coarse, close, loose, etc.) resulting from a way in which it is woven. • The constitution, structure, or substance of anything with regard to its constituents or formative elements. • Something composed of closely interwoven or intertwined threads, strands, or the like elements. • The essential part of something, an identifying quality. • The size and organization of small constituent part of a body or substance; the visual or tactile surface characteristics and appearance of something. The exact meaning of texture depends on the application area. While in geology it is a physical appearance or rock character, in material science it is a distribution M. Haindl, J. Filip, Visual Texture, Advances in Computer Vision and Pattern Recognition, DOI 10.1007/978-1-4471-4902-6_1, © Springer-Verlag London 2013
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1 Motivation
Fig. 1.1 Brodatz “texture” D44 [1] and two of its cutouts
of crystallographic orientations, in soil research it describes the proportion of grain sizes, in cosmology it is a type of a topological defect, for artists it is the look and feel of the canvas, for graphic designers it is often any image mapped onto a surface, etc. Although the notion of visual texture is tied to the human semantic meaning and texture analysis is an important area of image processing, there is no mathematically rigorous definition of texture that would be accepted throughout the computer vision community. Sometimes even its interpretation is subjective. E.g., is the Brodatz [1] texture D44 (Fig. 1.1) really a texture? This image obviously violates the homogeneity condition (see below), if not others as well. Rather th
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