imager (version 0.42.10)

vanvliet: Young-Van Vliet recursive Gaussian filter.

Description

The Young-van Vliet filter is a fast approximation to a Gaussian filter (order = 0), or Gaussian derivatives (order = 1 or 2).

Usage

vanvliet(im, sigma, order = 0L, axis = "x", neumann = FALSE)

Arguments

im

an image

sigma

standard deviation of the Gaussian filter

order

the order of the filter 0,1,2,3

axis

Axis along which the filter is computed. One of 'x', 'y', 'z', 'c'

neumann

If true, use Neumann boundary conditions (default false, Dirichlet)

References

From: I.T. Young, L.J. van Vliet, M. van Ginkel, Recursive Gabor filtering. IEEE Trans. Sig. Proc., vol. 50, pp. 2799-2805, 2002. (this is an improvement over Young-Van Vliet, Sig. Proc. 44, 1995)

Boundary conditions (only for order 0) using Triggs matrix, from B. Triggs and M. Sdika. Boundary conditions for Young-van Vliet recursive filtering. IEEE Trans. Signal Processing, vol. 54, pp. 2365-2367, 2006.

Examples

# NOT RUN {
vanvliet(boats,sigma=2,order=0) %>% plot("Zeroth-order Young-van Vliet along x")
vanvliet(boats,sigma=2,order=1) %>% plot("First-order Young-van Vliet along x")
vanvliet(boats,sigma=2,order=1) %>% plot("Second-order Young-van Vliet along x")
vanvliet(boats,sigma=2,order=1,axis="y") %>% plot("Second-order Young-van Vliet along y")
# }