Smooth a Matrix

The values on the edge of the matrix are unaltered. For interior points, the result is defined in terms in terms of the original as follows. \(r_{i,j} = (2 m_{i,j} + m_{i-1,j} + m_{i+1,j} + m_{i,j-1} + m_{i,j+1})/6\). Note that missing values propagate to neighbours.

Usage

matrixSmooth(m, passes = 1)

Arguments

m

a matrix to be smoothed.

passes

an integer specifying the number of times the smoothing is to be applied.

Value

A smoothed matrix.

Author

Dan Kelley

Examples

library(oce)
opar <- par(no.readonly = TRUE)
m <- matrix(rep(seq(0, 1, length.out = 5), 5), nrow = 5, byrow = TRUE)
m[3, 3] <- 2
m1 <- matrixSmooth(m)
m2 <- matrixSmooth(m1)
m3 <- matrixSmooth(m2)
par(mfrow = c(2, 2))
image(m, col = rainbow(100), zlim = c(0, 4), main = "original image")
image(m1, col = rainbow(100), zlim = c(0, 4), main = "smoothed 1 time")
image(m2, col = rainbow(100), zlim = c(0, 4), main = "smoothed 2 times")
image(m3, col = rainbow(100), zlim = c(0, 4), main = "smoothed 3 times")

par(opar)