def image2pencil(imagepath):

  image = cv2.imread(imagepath)

  imagename=str(imagepath).split(".")[0]

  cv2.imshow(imagename, image)

  cv2.waitKey(0)



  # BGR2GRAY  转换成灰阶（黑白图）
  gray_image = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)

  cv2.imshow(imagename, gray_image)

  cv2.imwrite(imagename+"_gray.jpg",gray_image)

  cv2.waitKey(0)



  # #反转片
  inverted_image = 255 - gray_image

       # cv2.imshow("Inverted", inverted_image)
  cv2.waitKey()

  blurred = cv2.GaussianBlur(inverted_image, (21, 21), 0)
  inverted_blurred = 255 - blurred

  pencil_sketch = cv2.divide(gray_image, inverted_blurred, scale=256.0)

  cv2.imshow(imagename, pencil_sketch)

  cv2.imwrite(imagename + "_pencil.jpg", pencil_sketch)

  cv2.waitKey(0)




image2pencil("test.jpg")