ISSN : 1796-203X
Volume : 2    Issue : 7    Date : September 2007

Two-Dimensional Digital Filters with Variable Magnitude Characteristics Obtained from a 1-D
Monotonic Response
Venkat Ramachandran, Christian S. Gargour, and Ravi P. Ramachandran
Page(s): 32-39
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A method for the generation of discretedomain two-dimensional (2-D) transfer functions
possessing variable magnitude and contour characteristics is presented in this paper. The
proposed method is based upon a configuration constituted by two 1-D filters in cascade and a
feedback loop. Each of these 1-D filter is designed to have a monotonic magnitude frequency
response. This is obtained by performing one or several integrations, either with respect to ω or ω2,
of the denominator of a magnitude Butterworth low-pass frequency response and obtaining the
corresponding modified transfer function. The variable characteristics in each domain are obtained
by changing a multiplier either in the forward path or in the feedback path of the proposed general
configuration. The use of a generalized bilinear transformation (GBT) on the transfer functions
obtained by the above mentioned method permits the generation of a large number of different
characteristics. A certain number of these characteristics is examined in some detail. Illustrative
examples are provided.

Index Terms
2-D discrete filters, variable magnitude.