distance_transform {imager}

Compute Euclidean distance function to a specified value.

Description

The distance transform implementation has been submitted by A. Meijster, and implements the article 'W.H. Hesselink, A. Meijster, J.B.T.M. Roerdink, "A general algorithm for computing distance transforms in linear time.", In: Mathematical Morphology and its Applications to Image and Signal Processing, J. Goutsias, L. Vincent, and D.S. Bloomberg (eds.), Kluwer, 2000, pp. 331-340.' The submitted code has then been modified to fit CImg coding style and constraints.

Usage

distance_transform(im, value, metric = 2L)

Arguments

im

an image

value

Reference value.

metric

Type of metric. Can be 0=Chebyshev | 1=Manhattan | 2=Euclidean | 3=Squared-euclidean.

Examples

imd <- function(x,y) imdirac(c(100,100,1,1),x,y)
#Image is three white dots
im <- imd(20,20)+imd(40,40)+imd(80,80)
plot(im)
#How far are we from the nearest white dot? 
distance_transform(im,1) %>% plot