OpenCV 按轮廓裁剪图像 ROI（掩膜 mask）

import cv2
import numpy as np

img = cv2.imread('lingbosize.png')
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
ret,thresh = cv2.threshold(gray,0,255,cv2.THRESH_BINARY_INV|
                           cv2.THRESH_OTSU)

contours,hierarchy = cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
mask = np.zeros(img.shape,np.uint8)#原图大小的纯黑图
draw = np.zeros(img.shape,np.uint8)#将原图copy 到 draw上,加上mask操作
temp = np.zeros(img.shape,np.uint8)#每次循环,重置mask 和 draw
i = 0


for contour in contours:
    area = cv2.contourArea(contour)
    print(f"AREA:{area}")
    B = 255
    G = 255
    R = 255
    mask = temp.copy()
    draw = temp.copy()
    if(area > 300):
        cv2.drawContours(mask,contour,-1,(B,G,R),cv2.FILLED)#cv2.FILLED填充轮廓内
        ROIname = 'ROI{}'.format(i)
        ROI = cv2.bitwise_and(img,mask)
        cv2.imshow(ROIname,ROI)
        i+=1
cv2.waitKey(0)
cv2.destroyAllWindows()