Normalization of blur of the image using Laplacian

Question

I have an image and I am interested in computing the blurr present in the image; for that I have used openCV in build functionality called cv2.Laplacian(image). But I could able to quantify the amount of blur present in the image. Is there anyway that we can compute a normalized value of the blur for a given image.

def blur(path):
    image = cv2.imread(path)
    gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
    fm = cv2.Laplacian(gray, cv2.CV_64F).var()
    return fm