Two-dimensional perfect reconstruction FIR filter banks with triangular supports

In this paper, we present a theory and design of two-dimensional (2-D) perfect reconstruction (PR) filter-banks (FB's) (PRFB's) in which the supports of the analysis and synthesis filters consist of two triangulars. The two-triangular FB can be realized by designing an appropriate 2-D complex prototype whose passband support is a triangle that is a half of parallelepiped-shaped passband support defined by sampling matrix. Then a complex prototype filter is modulated by DFT, and each analysis filter is derived by taking the real part of the modulated output. We show that the two-triangular FB satisfies the condition of permissibility. A necessary and sufficient condition for 2-D PRFB's will be derived. Moreover, we present a design method of the 2-D PRFB that minimizes the cost function consisting of the frequency constraint and PR condition. Finally, a design example is presented to confirm the validity of the proposed method.