Gait Biometrics, Overview
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bor Transform A complete representation of a signal or image in terms of coefficients on Gabor wavelets, such that the original data can be reconstructed exactly by combining together those wavelets using their computed coefficients. A complication is that the necessary coefficients cannot be obtained simply by operations of filtering or by the inner product projections of the data with the wavelets, since they do not constitute an orthogonal basis. More complex methods are required (biorthogonal bases; relaxation networks) to obtain the needed expansion coefficients from projection coefficients. Once obtained, a Gabor Transform is a powerful tool for signal or image encoding, analysis, and compression. ▶ Iris Encoding and Recognition using Gabor
Wavelets
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2009 Springer Science+Business Media, LLC
Gabor Wavelets Complex exponentials (Fourier components) multiplied by Gaussian envelopes. Although they fail to satisfy some parts of the stricter mathematical definitions of wavelets, such as orthogonality and compact support, these elementary functions can constitute a powerful basis for signal or image encoding, representation, compression, and analysis. They are increasingly used today in computer vision and in pattern recognition, particularly in biometrics, where they are the basis of iris recognition and have also been used for several other biometric modalities. Among their advantages (besides forming a complete basis for signal or image encoding) are; their optimality under the Heisenberg Uncertainty Principle for simultaneous resolution in time/space and in frequency; their closed analytical form; their self-Fourier property and closure under convolution and multiplication; and their neurobiological basis in the receptive field profiles of neurons in the mammalian visual cortex. Their chief disadvantage is that they are not mutually orthogonal, and so the projection coefficients obtained by computing their inner product with an image are not the same as the expansion coefficients that would be needed to reconstruct the same image exactly from them. ▶ Face Recognition, Component Based ▶ Iris Encoding and Recognition using
Wavelets ▶ Local Image Features ▶ Local Image Filters
Gabor
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Gait
Gait The manner of a person’s movement, specifically during walking is called gait. The human gait cycle consists of two main phases: during stance phase, the foot is on the ground, and during the swing phase, the leg is swinging forward in preparation for the next ground contact. ▶ Gait, Forensic Evidence of
Gait Analysis ▶ Gait, Forensic Evidence of
Gait Biometrics, Overview R AMA C HELLAPPA , A SHOK V EERARAGHAVAN N ARAYANAN R AMANATHAN University of Maryland, College Park, MD, USA
Synonym Gait recognition
Definition Gait is defined as the style or manner of walking. Studies in physchophysics suggest that people can identify familiar individuals using just their gait. This has led to a number of automated vision based algorithms that use gait as a biometric. Such a system usually consists of a video camera c
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