cv2.Canny 中的低阈值参数和高阈值参数有什么区别？

Question

I want to apply Canny function to the image to detect the edges.

This is how the function looks like:

cv2.Canny(image, threshold1, threshold2, apertureSize, L2gradient)

threshold1: It is the High threshold value of intensity gradient.

threshold2: It is the Low threshold value of intensity gradient.

I do not understand the difference between threshold1 and threshold2. I searched it online but I am still not able to understand it.

Here is my original image:

An example with low threshold1 and high threshold2:

canny_low_threshold1 = cv2.Canny(blurred_image, 10, 100)
cv2.imshow("low_threshold1", canny_low_threshold)

Here is the exact opposite:

canny_high_threshold1 = cv2.Canny(blurred_image, 100, 10 )
cv2.imshow("high_threshold1", canny_high_threshold1)

They produce exactly the same output. Could somebody please explain me the difference?

Answer 1

For example, We have points A,B, C.If point A is higher than the maxVAl it is considered as an edge, if B is inbetween maxVal and minVal, and the point B is not connected to the pointA which is above the maxVal it is not observed as an edge. If point C is below minVal it is not considered as an edge at all. The maxVal and minVal tend to separate potential edges from false edges