watershed {imager} | R Documentation |
Compute watershed transform.
Description
The watershed transform is a label propagation algorithm. The value of non-zero pixels will get propagated to their zero-value neighbours. The propagation is controlled by a priority map. See examples.
Usage
watershed(im, priority, fill_lines = TRUE)
Arguments
im |
an image |
priority |
Priority map. |
fill_lines |
Sets if watershed lines must be filled or not. |
Examples
#In our initial image we'll place three seeds
#(non-zero pixels) at various locations, with values 1, 2 and 3.
#We'll use the watershed algorithm to propagate these values
imd <- function(x,y) imdirac(c(100,100,1,1),x,y)
im <- imd(20,20)+2*imd(40,40)+3*imd(80,80)
layout(t(1:3))
plot(im,main="Seed image")
#Now we build an priority map: neighbours of our seeds
#should get high priority.
#We'll use a distance map for that
p <- 1-distance_transform(sign(im),1)
plot(p,main="Priority map")
watershed(im,p) %>% plot(main="Watershed transform")
[Package imager version 1.0.2 Index]