OpenCV实现将任意形状ROI区域置黑

比较常用的是将 Rect 矩形区域置黑，代码如下：

int testMaskRectROI() {
    cv::Mat image = cv::imread("./test_img/detect_pic.jpeg");

    cv::Rect rect_mask(57, 93, 92, 92);
    cv::Mat subImage = image(rect_mask);
    subImage.setTo(0);

    cv::imshow("src", image);
    cv::waitKey(0);
}

效果如下：

但在做人脸检测的旋转追踪时，矩形框是随角度旋转的，那如何处理呢？直接上代码：

int testMaskAnyROI() {
    cv::Mat image = cv::imread("./test_img/detect_pic.jpeg");

    vector<cv::Point> contour;
    contour.push_back(cv::Point(66, 80));
    contour.push_back(cv::Point(38, 177));
    contour.push_back(cv::Point(134, 205));
    contour.push_back(cv::Point(162, 108));

    vector<vector<cv::Point> > contours;
    contours.push_back(contour);
    cv::drawContours(image, contours, -1, cv::Scalar::all(0), CV_FILLED);

    cv::imshow("src", image);
    cv::waitKey(0);
}

效果如下：