On the Multidimensional Extension of the Quincunx Subsampling Matrix
D. Van De Ville, T. Blu, M. Unser
IEEE Signal Processing Letters, vol. 12, no. 2, pp. 112-115, February 2005.
The dilation matrix associated with the three-dimensional (3-D) face-centered cubic (FCC) sublattice is often considered to be the natural 3-D extension of the two-dimensional (2-D) quincunx dilation matrix. However, we demonstrate that both dilation matrices are of different nature: while the 2-D quincunx matrix is a similarity transform, the 3-D FCC matrix is not. More generally, we show that is impossible to obtain a dilation matrix that is a similarity transform and performs downsampling of the Cartesian lattice by a factor of two in more than two dimensions. Furthermore, we observe that the popular 3-D FCC subsampling scheme alternates between three different lattices: Cartesian, FCC, and quincunx. The latter one provides a less isotropic sampling density, a property that should be taken into account to properly orient 3-D data before processing using such a subsampling matrix.
@ARTICLE(http://bigwww.epfl.ch/publications/vandeville0501.html, AUTHOR="Van De Ville, D. and Blu, T. and Unser, M.", TITLE="On the Multidimensional Extension of the Quincunx Subsampling Matrix", JOURNAL="{IEEE} Signal Processing Letters", YEAR="2005", volume="12", number="2", pages="112--115", month="February", note="")