Modified Technique

The algorithm described in Wolfson et al. (1999) can be done equivalently as follows:

1. Compute the weighted average at each pixel of the original image where the weights are non-zero only where the elliptical filters (see Figure 1) have cross-hatched pixels.
2. Repeat Step 1 for every orientation of the elliptical filters.
3. Set each pixel of the final image to be the maximum value at the same pixel location (same row and same column) of the filtered images at each orientation.

The main difference between (Wolfson et al., 1999) and the operations listed above is the order in which the operations are performed. The maximum is computed after the entire image has been filtered by the elliptical filter rather than after each pixel of the output has been computed. Sections 2.3 and 2.4 simply show that the algorithm described above is equivalent to the algorithm described in Section 2.1. Under some simplifying conditions, it is shown that Step 1 can be speeded up using Fast Fourier Transforms.