Steerable Filters from Erlang Functions
Anil Anthony Bharath · 1998
Scale and orientation steerable 2D filters are constructed using a frame of Erlang functions in the Fourier domain. Erlang forms for the radial frequency characteristic are shown to provide complex quadrature filters which can be steered in a scale parameter, #. Oriented, spatial domain filters are constructed by imposing an appropriate angular selectivity in the frequency domain. A filter bank is designed, and outputs of the filters of the bank are steered to construct an oriented scale-space decomposition of an image subband. Some applications are discussed. 1 Introduction The use of sub-band methods in image analysis is perhaps not as widespread as for coding. Nevertheless, quite successful and powerful analysis algorithms have been demonstrated [1]. One can make good use of sub-band processing when image features exist at several scales, so that operators of different sizes must be employed: a key issue then becomes the design of these operators. This paper, in a manner similar to...