  This paper addresses streak reduction in limited angle tomography. Although
the iterative reweighted total variation (wTV) algorithm reduces small streaks
well, it is rather inept at eliminating large ones since total variation (TV)
regularization is scale-dependent and may regard these streaks as homogeneous
areas. Hence, the main purpose of this paper is to reduce streak artifacts at
various scales. We propose the scale-space anisotropic total variation (ssaTV)
algorithm in two different implementations. The first implementation (ssaTV-1)
utilizes an anisotropic gradient-like operator which uses 2s neighboring pixels
along the streaks' normal direction at each scale s. The second implementation
(ssaTV-2) makes use of anisotropic down-sampling and up-sampling operations,
similarly oriented along the streaks' normal direction, to apply TV
regularization at various scales. Experiments on numerical and clinical data
demonstrate that both ssaTV algorithms reduce streak artifacts more effectively
and efficiently than wTV, particularly when using multiple scales.
