Structure adaptive anisotropic image filtering

Adaptive enhancement and noise reduction in very low light-level video

“…An approach that is closely connected to both bilateral filtering, and to anisotropic diffusion techniques based on the structure tensor, is the structure-adaptive anisotropic filtering presented by Yang et al [28]. In our search for an optimal strategy to apply spatio-temporal summation for noise reduction in low light-level video, we naturally settled for this approach.…”

“…We will now review the structure-adative anisotropic image filtering by Yang et al [28] and present our modifications and extensions to improve its applicability and make it suitable for our low-light level vision objective.…”

“…The theory in [28] is mainly developed for 2D images and measures of corner strength and of anisotropism, both involving ratios of the maximum and minimum eigenvalues, are there calculated at every point x 0 . An extention of this to the 3D case is then discussed.…”

Fingerprint Image Enhancement using Filtering Techniques

“…In this section we present a new direct gray-scale approach based on a unique anisotropic filter. A structureadaptive anisotropic filtering technique is proposed by Yang [14] for image filtering. Instead of using local gradients as a means of controlling the anisotropism of filters, it uses both a local intensity orientation and an anisotropic measure to control the shape of the filter.…”

“…The basic idea is that the filter kernel is shaped or scaled according to local features within a given neighborhood. The filter kernel applied at each point x 0 is defined as follows [14]:…”