python+opencv ROI 操作

import cv2 as cv
import numpy as np


src=cv.imread('D:/pycharm/pycharmproject/test.jpg')
roi=src[100:250, 200:300]
# cv.imshow('roi',roi)
gray=cv.cvtColor(roi,cv.COLOR_BGR2GRAY)
gray=cv.cvtColor(gray,cv.COLOR_GRAY2BGR)
cv.imshow('src1',src)
src[100:250, 200:300]=gray
cv.imshow('gray',gray)
cv.imshow('src2',src)
# cv.imshow('gray',gray)
cv.waitKey(0)
cv.destroyAllWindows()