def find_blobs_distance(img):

    blobs = img.find_blobs([find_blobs_threshold])
    if len(blobs) == 1:
         # Draw a rect around the blob.
            b = blobs[0]
            img.draw_rectangle(b[0:4]) # rect
            img.draw_cross(b[5], b[6]) # cx, cy 
            Lm = (b[2]+b[3])/2
            length = K/Lm
            distances.dist = int(length)
请在这里粘贴代码