2-D digital filter
Apply a 2-D digital filter to the data in x.
filter2(h, x, shape = c("same", "full", "valid"))h |
transfer function, specified as a matrix. |
x |
numeric matrix containing the input signal to be filtered. |
shape |
Subsection of convolution, partially matched to:
|
The filter2 function filters data by taking the 2-D convolution of the
input x and the coefficient matrix h rotated 180 degrees. More
specifically, filter2(h, x, shape) is equivalent to conv2(x,
rot90(h, 2), shape).
The filtered signal, returned as a matrix
Paul Kienzle. Conversion to R by Geert van Boxtel, G.J.M.vanBoxtel@gmail.com.
op <- par(mfcol = c(1, 2))
x <- seq(-10, 10, length.out = 30)
y <- x
f <- function(x, y) { r <- sqrt(x^2+y^2); 10 * sin(r)/r }
z <- outer(x, y, f)
z[is.na(z)] <- 1
persp(x, y, z, theta = 30, phi = 30, expand = 0.5, col = "lightblue")
title( main = "Original")
h <- matrix(c(1, -2, 1, -2, 3, -2, 1, -2, 1), 3, 3)
zf <-filter2(h, z, 'same')
persp(x, y, zf, theta = 30, phi = 30, expand = 0.5, col = "lightgreen")
title( main = "Filtered")
par(op)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.