This paper examines the structure underlying textural patterns. To this end, aspects of a model for texture are developed on the basis of both perceptual processes of the observer and structural properties of the patterns. Local constructs called primitives serve as generators for globally perfect, but unobservable, ideal textures. Study of the graph representation of these ideal textures reveals the basic regularity underlying visual textures. These perfect patterns are then transformed into observable textures by transformations which must not violate psychophysically based restrictions. Interpretively ambiguous textural patterns are used to demonstrate the influence that local primitives have on the formation of global pattern organizations.