Design of zero-phase recursive 2-D variable filters with quadrantal symmetries (Q1842536)

Samples taken at scattered points of a finite support two-dimensional signal can be interpolated to recover an approximation of the original signal. Given a number of samples, where should they be placed to enable a most accurate reconstruction? In this paper the authors introduce search schemes that provide good candidates for the solution to these problems, for digital signals. Natural neighbour interpolation is used in an iterative sample removal and movement process to obtain sparse sample patterns. For pictures and digital elevation models, fewer samples are required if the interpolation is only continuous at the data sites, then if it is continuous with derivatives. Retained samples lies on rigdes and valleys of the Laplacian.