如何在android中使用opencv访问轮廓区域内的像素并写回原始图像

import org.opencv.core.Mat;
import org.opencv.core.MatOfPoint;
import org.opencv.core.Point;
import org.opencv.core.Scalar;
import org.opencv.core.Size;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;

public class MainActivity extends AppCompatActivity {

    static {
        System.loadLibrary("opencv_java4");
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // 加载图像并转换为Mat对象
        Mat image = Imgcodecs.imread("path_to_image");

        // 转换为灰度图像
        Mat grayImage = new Mat();
        Imgproc.cvtColor(image, grayImage, Imgproc.COLOR_BGR2GRAY);

        // 进行边缘检测
        Mat edges = new Mat();
        Imgproc.Canny(grayImage, edges, 50, 150);

        // 找到轮廓
        List<MatOfPoint> contours = new ArrayList<>();
        Mat hierarchy = new Mat();
        Imgproc.findContours(edges, contours, hierarchy, Imgproc.RETR_EXTERNAL, Imgproc.CHAIN_APPROX_SIMPLE);

        // 访问轮廓区域内的像素并修改像素值
        for (MatOfPoint contour : contours) {
            for (Point point : contour.toArray()) {
                double[] pixel = image.get((int) point.y, (int) point.x);
                // 修改像素值
                pixel[0] = 255;  // 修改为白色
                pixel[1] = 255;
                pixel[2] = 255;
                image.put((int) point.y, (int) point.x, pixel);
            }
        }

        // 将修改后的图像写回原始图像文件
        Imgcodecs.imwrite("path_to_output_image", image);
    }
}