python实现局部图像放大

import cv2 as cv
import sys
if __name__ == '__main__':
 #读取图像并判断是否读取成功
 img = cv.imread('tu.jpg')
 #需要放大的部分
 part = img[300:400,250:350]
 #双线性插值法
 mask = cv.resize(part, (300, 300), fx=0, fy=0, interpolation=cv.INTER_LINEAR)
 if img is None is None:
  print('Failed to read picture')
  sys.exit()
  
 #放大后局部图的位置img[210:410,670:870]
 img[110:410,570:870]=mask
 #画框并连线
 cv.rectangle(img,(250,300),(350,400),(0,255,0),1)
 cv.rectangle(img,(570,110),(870,410),(0,255,0),1)
 img = cv.line(img,(350,300),(570,110),(0,255,0))
 img = cv.line(img,(350,400),(570,410),(0,255,0))
 #展示结果
 cv.imshow('img',img)
 cv.waitKey(0)
 cv.destroyAllWindows()