This textbook presents a systematic, mathematically rigorous examination of modern signal processing concepts used in computer vision and image analysis. This is the first reference to employ a single concept: direction tensors, to explore single direction, group direction, corners and edges, and motion estimation. Topics include Hilbert spaces, Fourier transform, scale analysis, direction fields, structure tensor, motion tensor, Hough transform, grouping, and segmentation. The book is richly illustrated with 4-color graphics and applications, including biometric person authentication, texture analysis, optical character recognition, motion estimation and tracking.