Java Opencv未检测轮廓。imgproc.Drawcontours()

import org.opencv.core.*;
import org.opencv.imgproc.Imgproc;

public class DrawContoursExample {
    public static void main(String[] args) {
        // 加载OpenCV库
        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);

        // 读取图像
        Mat image = Imgcodecs.imread("path/to/image.jpg");

        // 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, 100, 200);

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

        // 绘制轮廓
        Scalar contourColor = new Scalar(0, 255, 0); // 绿色
        int contourThickness = 2;
        Imgproc.drawContours(image, contours, -1, contourColor, contourThickness);

        // 显示结果
        HighGui.imshow("Contours", image);
        HighGui.waitKey();
    }
}