Abstract
A new and numerically efficient technique for designing two-dimensional (2-D) separable-denominator digital filters using Schur decomposition (SD) and the diagonal symmetry of the 2-D impulse response specifications. This technique is based on two steps: first, the 2-D impulse response specifications are decomposed into two cascaded specifications, representing SIMO and MISO 1-D digital filters. By using the symmetry property of the 2-D impulse response matrix and that the left and right eigenspaces obtained by SD are a transpose of each other, the design problem of the two 1-D digital filters is reduced to the design problem of only one 1-D digital filter. Thus, the computational effort is reduced by approximately half. Further computational reduction is obtained by applying the SD to only part of the 2-D impulse response matrix, the leading principal minor submatrix, and from the symmetry property of the class of filters that are considered here, the decomposition of the impulse response matrix is obtained. In the second step, a model reduction algorithm is used to design a filter that approximates the 1-D specifications obtained from the first step. Two design examples illustrate the advantages of the proposed technique.