Automatic calculation of low and high thresholds for the Canny operation in opencv

Question

In openCV, the low and high thresholds for the canny operator are mandatory:

cvCanny(input,output,thresh1,thresh2)

In Matlab, there\'s an o

Answer 1

Check out this link: http://www.pyimagesearch.com/2015/04/06/zero-parameter-automatic-canny-edge-detection-with-python-and-opencv/

They implement a similar solution using basic statistics to determine the low and high threshold for Canny edge detection.

def auto_canny(image, sigma=0.33):
     # compute the median of the single channel pixel intensities
     v = np.median(image)

    # apply automatic Canny edge detection using the computed median
    lower = int(max(0, (1.0 - sigma) * v))
    upper = int(min(255, (1.0 + sigma) * v))
    edged = cv2.Canny(image, lower, upper)

    # return the edged image
    return edged