D-DIMENSIONAL, FRACTIONAL BANDWIDTH SIGNAL PROCESSING APPARATUS

Filtering apparatus responsive to a sequence of samples of an input signal that is digitally-sampled at a given frequency, wherein the input signal defines information having at least one dimension. The apparatus includes first resampler for resampling the input-signal to derive a first signal at a first frequency which is substantially equal to the reciprocal 1/C of a given factor C times the given frequency, and second resampler for resampling the first signal to derive a second signal at a second frequency which is substantially equal to the given factor C times the first frequency. The given factor C is an improper fraction having a least-common-denominator larger than one. This filtering apparatus is particularly suitable for variably spatially low-pass, high-pass, band-pass or hierarchical-pyramid filtering two-dimensional image information in each of its two-dimensions by amounts which are independent of one another.