dilation {VPdtw}

Compute a morphological dilation of a signal

Description

A dilation is a moving local maximum over a window of specific fixed width specified by span. This dilation is computed first in one direction and then in the other.

Usage

dilation(y, span)

Arguments

y

signal, a numeric vector

span

the width of the moving window, integer

Details

A dilation is a method often used in mathematical morphology and image analysis (Soille 1999). This function is for vectors not matrices or images though applying it to rows and columns of a matrix will give the corresponding results.

An erosion of a vector or image can also be computed easily from this by computing the dilation of -1 times the vector and transforming back.

We recommend using a dilation to form a penalty for use in VPdtw.

Value

res

Dilation of y with width span

Author(s)

David Clifford

References

Soille, P. Morphological Image Analysis: Principles and Applications; Springer: New York, 1999.

Examples

## Example 1 - dilation of a signal
data(reference)
dref <- dilation(reference,150)
plot(reference,log="y",type="l")
lines(dref,col=2)

## Example 2 - dilation of an image
BIN <- (volcano>177)
dBIN <- t(apply(BIN,1,dilation,span=5))
dBIN <- apply(dBIN,2,dilation,span=5)
oldpar <- par(no.readonly = TRUE)
par(mfrow=c(2,2))
image(volcano)
image(BIN)
image(dBIN)
par(oldpar)