Achieving real-time LoG filtering

A recursive algorithm has been developed for LoG filtering. We use an analytic method to obtain the z-transform of LoG function in a rational function form. The structure of the recursive filters is defined by the order of rational functions. The computational complexity of recursive filtering depends on the number of poles and zeros of the transfer function, i.e., on the structure of the recursive filter. It is independent of the size of the filter, and thus has a substantial saving in computation. The algorithm gives a constant computation complexity per pixel. Various images have been tested. A general method of designing high order recursive filters is also given.