Binary low, high and band pass amplitude filters with full and quantised phase in the presence of disjoint input noise

Filtering techniques that operate in the spatial frequency domain of a digital or coherent optical correlator, manipulate the amplitude and phase information of the reference and input spectral components. Three different techniques to modify the filter from the full complex version are discussed in this paper; binary low, high and band pass amplitude / phase filtering. These filters may be used for applications where disjoint noise is present in the input. The reduction of the phase resolution is also investigated which therefore offers less processing time without significantly affecting the invariance properties of such filters. It is shown that these filters identify the target in the presence of realistic landscapes, giving a reasonable scaling and rotation invariance range as well.