Analytic Design Method and Applications of Two-Directional Wedge- Type Filters

This work proposes some mathematical methods used in the design of a class of two-dimensional recursive filters, with an orientation-selective frequency response. We propose an analytical design method based on a given 1D digital prototype filter and a frequency transformation determined using Chebyshev-Padé approximations and the bilinear transform. These filters may find useful applications in image processing, like detecting lines with a given orientation from an image, as we show through simulation results. The resulted filters are very efficient, being at the same time of low complexity and relatively high selectivity. Simulation results are provided which show their image filtering capabilities. Key-Words: Two-dimensional filter design, approximation theory, complex frequency transformations