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A method of design for a class of 2‐D filters
Author(s) -
Prasad K. P.,
Unbehauen R.
Publication year - 1984
Publication title -
international journal of circuit theory and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.364
H-Index - 52
eISSN - 1097-007X
pISSN - 0098-9886
DOI - 10.1002/cta.4490120203
Subject(s) - transfer function , mathematics , factorization , polynomial , digital filter , frequency domain , computation , filter (signal processing) , algorithm , computer science , mathematical analysis , electrical engineering , computer vision , engineering
This paper discusses a method of designing quadrantally symmetric cascaded two‐dimensional (2‐D) digital recursive filters by subjecting a one variable approximating function to successive transformations. the needed approximation is done in the one variable domain rather than in the 2‐D domain, hence leading to a large reduction of computational labour. Using cepstral techniques each denominator polynomial is spectrally factorized into recursible non‐symmetric half plane components. A significant feature of the method is in decoupling the problems of approximation and stability. Consequently spectral factorization needs to be performed only once for each denominator polynomial. Effects of truncation on filter stability are minimized by ensuring rapid convergence of cepstra. the choice of an adequate DFT size in cepstral computations is shown to be an important consideration for many problems associated with spectral decomposition. Attempts are also made to stabilize the unstable transfer function using an existing 2‐D discrete Hilbert transform method. Considerable distortion in magnitude characteristics is shown to result on stabilization. Finally the method is illustrated by two examples.