Non-separable extensions of quadrature mirror filters to multiple dimensions

Generalized non-separable extensions of quadrature mirror filter (QMF) banks to two and three dimensions, in which the orientation specificity of the high-pass filters is greatly improved, are described. In particular, extensions to two dimensions with hexagonal symmetry, and 3-D spatiotemporal extensions with rhombic-dodecahedral symmetry, are discussed. Although these filters are conceived and designed on nonstandard sampling lattices, they can be applied to rectangularly sampled images. As in one dimension, these transformations can be hierarchically cascaded to form a multiscale pyramid representation. A set of example filters is designed and applied to the problems of image compression, progressive transmission, orientation analysis, and motion analysis.