OpenCV根据多边形抠图

import cv2
import numpy as np
import json

P = []
with open('test.json') as f:
    datas = f.readlines()
    for data in datas:
        data = data.strip()
        annotations = json.loads(data)['annotation']
        annotation = annotations[0]
        points = annotation['points']
        imageWidth = annotation['imageWidth']
        imageHeight = annotation['imageHeight']
        for point in points:
            point[0] *= imageWidth
            point[1] *= imageHeight
            P.append([int(point[0]),int(point[1])])

originalimg = cv2.imread('/home/lixuan/data/466yuanshi/f/t1.jpg')
img = np.zeros((imageHeight, imageWidth, 3), np.uint8)
area1 = np.array(P)

cv2.fillPoly(img, [area1], (255, 255, 255))
maskindex = np.where(img > 0)
img[maskindex] = originalimg[maskindex]
cv2.imshow('',img)
cv2.waitKey(0)