imager (version 0.42.19)

cannyEdges: Canny edge detector

Description

If the threshold parameters are missing, they are determined automatically using a k-means heuristic. Use the alpha parameter to adjust the automatic thresholds up or down The thresholds are returned as attributes. The edge detection is based on a smoothed image gradient with a degree of smoothing set by the sigma parameter.

Usage

cannyEdges(im, t1, t2, alpha = 1, sigma = 2)

Arguments

im

input image

t1

threshold for weak edges (if missing, both thresholds are determined automatically)

t2

threshold for strong edges

alpha

threshold adjusment factor (default 1)

sigma

smoothing

Author

Simon Barthelme

Examples

cannyEdges(boats) %>% plot
#Make thresholds less strict
cannyEdges(boats,alpha=.4) %>% plot
#Make thresholds more strict
cannyEdges(boats,alpha=1.4) %>% plot