cv2和PIL对图像进行padding的区别

import cv2
import numpy as np
from PIL import Image,ImageOps
import copy
img = cv2.imread('F:\\2\\images.jpg')
img=cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
print(img.shape)
img2=copy.deepcopy(img)
constant = cv2.copyMakeBorder(img, 0, 0, 50, 100, cv2.BORDER_CONSTANT, value=0)#top,bottom,left,right

cv2.imshow('pistol', constant)
print(constant.shape)
cv2.waitKey(0)

constant2=Image.fromarray(img2)
print(img2.shape)
constant2=ImageOps.expand(constant2, border=(50,0,100,0), fill=0)##left,top,right,bottom

constant2=np.asarray(constant2)
print(constant2.shape)
print(np.sum(constant2-constant))

(179, 281)
(179, 431)
(179, 281)
(179, 431)
0