主要思想是两张图相减，相同的部分会变为0，即图像为黑色。
PlanA
import matplotlib.image as pltimg
import matplotlib.pyplot as plt
image = pltimg.imread("./flower.jpg", 1)
image_01 = image.copy()
sub_image = image - image_01
plt.imshow(sub_image)
plt.show()
# plt.waitforbuttonpress(0)
PlanB
image = cv2.imread("./flower.jpg", 1)
img = image.copy()
result = cv2.subtract(image, img)
cv2.imshow("res", result)
cv2.waitKey()PlanC
