On M-channel linear phase FIR filter banks and application in image compression
This paper investigates the theory and structure of a large subclass of M-channel linear-phase perfect-reconstruction FIR filter banks-systems with analysis and synthesis filters of length L/sub i/=K/sub i/M+/spl beta/, where /spl beta/ is an arbitrary integer, 0/spl les//spl beta/<M, and K/sub i/ is any positive integer. For this subclass of systems, we first investigate the necessary conditions for the existence of linear-phase perfect-reconstruction filter banks (LPPRFBs). Next, we develop a complete and minimal factorization for all even-channel linear-phase paraunitary systems (the most general lapped orthogonal transforms to date). Finally, several design examples as well as comparisons with previous generalized lapped orthogonal transforms (GenLOTs) in image compression are presented to confirm the validity of the theory.