Efficient approximation of Gaussian filters

This correspondence presents improvements to the efficient approximation of Gaussian tilters by sequentially applying uniform hox filters. For 1-D fitters, a simple and nearly optimal fit criterion far the length N of the box filters to the approximated Gaussian is given For 2-D filters, a new method is introduced to improve the circular symmetry and the lowpass properties of the approximation without increasing the computational complexity. Finally, a multirate implementation for large Gaussian filters is presented that requires significantly fewer floating-point operations than the standard technique.