边缘检测项目（将边缘描绘出来）python opencv

import numpy as np
import cv2 as cv
from operator import itemgetter
video_capture = cv.VideoCapture('D:\python2\opencv_test\\vedio\\52816D2BD5CA004EA544D74F552C7B0A.mp4')

# video_capture.set(cv.CAP_PROP_POS_FRAMES, 200)#设置摄像头取的帧
while(1):
    flag, frame = video_capture.read()#把视频转化为图片帧
    height0= frame.shape[0]#设置图像的垂直尺寸
    frame_gray= cv.cvtColor(frame, cv.COLOR_BGR2GRAY)#转化为灰度图
    height, width = frame_gray.shape[0:2]#取图片的高与宽

    start_height1 = height0 // 4
    start_height2 = height0 // 4
    frame_ROI = frame_gray[start_height1:height0-start_height2, :]

    # cv.imshow('1',frame_ROI)

    ndiv = width#ndiv分几个块，div每一个块有几个像素
    div = width//ndiv
    frame_result=frame_ROI[:,0:div]
    for i in range(ndiv):
        if i<(ndiv-1):
            frame_temp=frame_ROI[:,i*div:(i+1)*div]
        else:
            frame_temp=frame_ROI[:,(ndiv-1)*div:width]
        ret,frame_temp = cv.threshold