This paper presents a new representation called " hierarchical Gabor filters " and associated novel local measures which are used to detect potential objects of interest in images. The " first stage " of the approach uses a wavelet set of wide-bandwidth separable Gabor filters to extract local measures from an image. The " second stage makes certain spatial… (More)
wireless communications, CDMA, multi-access communication, intermodulation distortion This paper investigates the effects of Walsh code selection and baseband filtering on the statistical moments of the bandlimited forward-link CDMA signal. A normalized moment, the " power variance " , is proposed as a measure of the signal's sensitivity to nonlinear… (More)
J.G. Daugman's (1988) neural network solution to the Gabor expansion of an image is reformulated as a steepest descent implementation. Nonlinear optimization theory is then applied to select an appropriate convergence factor. Two quasi-Newton-based nonlinear optimization techniques are applied to improve the convergence for certain types of lattice.
This paper describes how the phase, obtained by Gabor filtering an image, can be used to aggregate related Ga-bor elements (simple features identified by peaks in the Gabor magnitude). This phase-based feature grouping simplifies the perennial problem of target/background segmentation because we need to only determine if the aggregate feature is target or… (More)
Recognition of aircraft in complex, perspective aerial imagery has to be accomplished in presence of clutter, occlusion, shadow, and various forms of image degradation. This paper presents a system for aircraft recognition under real-world conditions that is based on the use of a hierarchical database of object models. The particular approach involves three… (More)
This paper develops an error bound for narrow band-width Gabor filters synthesized using multiple stages. It is shown that the error introduced by approximating narrow bandwidth Gabor kernels by a weighted sum of spatially offset, separable kernels is a function of the frequency offset and the reduction in bandwidth of the desired kernel compared to the… (More)