Fast LoG filtering using recursive filters

Marr and Hildreth's theory of LoG filtering with multiple scales has been extensively elaborated. One problem with LoG filtering is that it is very time-consuming, especially with a large size of filters. This paper presents a recursive convolution scheme for LoG filtering and a fast algorithm to extract zero-crossings. It has a constant computational complexity per pixel and is independent of the size of the filter. A line buffer is used to determine the locations of zero-crossings along with filtering hence avoiding the need for an additional convolution and extra memory units. Various images have been tested.