Attenuation characteristics of three-dimensional planar-resonant recursive digital filters

First-order planar-resonant 3-D recursive digital filters may be used to selectively enhance dynamic (i.e. time-varying) input signals that move in a straight line with approximately uniform speed in a 2-D image. An efficient method for determining the attenuation of such dynamic 2-D signals is described. It is shown that it is possible to use geometrical considerations to calculate the attenuation in terms of physically meaningful and observable parameters such as the orientation, trajectory and speed of the input signal in the dynamic 2-D image. For spatially elongated input objects, the spatial orientation of the object, as well as its 3-D trajectory, is found to have a significant role in determining the attenuation