Detects edges on a given image using the canny edge detection algorithm.
This function changes the input image and stores a visualized result of
cannys edge detection algorithm in it after this function terminatates.
If you dont want your image object to be changed, call image.clone() beforehand.
Canny edge detection is a multi stage algotithm. After each stage, the
resulting image can be viewed by utilizing onGrayConvertion,
onBlur, onSobel, onNonMaxSuppressed and onImageResult function parameters.
Do not change any pixels of the images of the intermediate steps, because
they are needed for the following steps. If you want to use the images
of the intermediate steps use image.clone()!
This function returns a set of all found edges, where an edge is a set
of edge-indicating pixels which are connected along the direction of
the edge.
lowThreshold and highThreshold parameters determine when a possible
edge is defenetly supressed (if signal is lower than lowThreshold) and
when an edge is defenetly preserved (if signal is higher than highThreshold).
If at least one of the thresholds are given, the other one is set to its
double or to its half. If no threshold is given, highThreshold is determined
by otsus method which splits an image into two classes (foreground & background)
and lowThreshold is set to half of highThreshold.
