Subband decomposition procedure for quincunx sampling grids
Chai W. Kim, Rashid Ansari · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1991
Filters with diamond shaped passbands and stopbands are used in image and video processing for several different tasks, one of which is the subband decomposition of signals. This subband decomposition can be carried out in a tree-structured manner by using diamond prefilters followed by downsampling on quincunx grids at each stage. In order to use such a decomposition in hierarchical coding it is desirable to choose the lowpass filter to be a halfband filter so as to limit the amount of aliasing in the low frequency component of the signal at each stage. This paper addresses the design and implementation of a two-channel filter bank for such an application. A special class of one-dimensional (1-D) prototype filters is used to derive the filter banks. The procedure is based on obtaining a halfband filter using a pair of lower order halfband filters. The resulting solutions preserve the exact reconstruction property even when the filter coefficients are quantized, a property which is useful in implementation. Examples of such filter banks are presented.