Quadrature-mirror-filter Design for the Subband Coding of Digital

This paper explores the design and use of Quadrature-Mirror-Filters (QMF) and Conjugate-Quadrature-Filters (CQF) within a two-dimensional framework for digital video applications, an example of which is the transmission system proposed by Schmidt [I]. The principles of subband coding are well known [2,3] and involve splitting an input signal into M-channel " a l l y decimated subbands, which in the special case of M=2, comprise complementary lowpass and highpass signals, as shown in Figure 1. Due to the non-ideal characteristics of the analysis bank filters and subsequent decimation, the subband signals suffer from three sources of error; namely aliasing, amplitude and phase distortion. The underlying design principle is that by judicious selection of the QMF-CQF structures which comprise the synthesis bank filters at the receiver, all three errors can be cancelled, so leading to the property of Perfii Reconstruction (PR) for the entire system.