Cosine-modulated two-dimensional time-varying filter banks

Two-dimensional (2D) filter banks are widely used for analysis and synthesis systems applied to subband coding of images. In recent years, time-varying filter banks that vary their structure appropriately for a local property of signals have been studied for application to the compression of image data. In time-varying filter banks, each different part of the signals is processed with different filter coefficients or different numbers of channels (a different sampling matrix). Those signals must be perfectly reconstructed even across transitions of the filter banks. In this paper, we consider time-varying systems of cosine-modulated 2D filter banks for arbitrary sampling lattices. We show perfect reconstruction (PR) conditions for time-varying filter banks that vary filter coefficients or a sampling matrix. Some applications are presented to show the effectiveness of this method. (C) 1997 Scripta Technica, Inc.