public static void main(String[] args)
  {
    // TODO Auto-generated method stub
    System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
    Mat src = Imgcodecs.imread("F:\\1_m1109048058.jpg");
    Mat dst = src.clone();
    Imgproc.cvtColor(dst, dst, Imgproc.COLOR_BGRA2GRAY);
    Imgproc.adaptiveThreshold(dst, dst, 255, Imgproc.ADAPTIVE_THRESH_MEAN_C,
        Imgproc.THRESH_BINARY_INV, 3, 3);
 
    java.util.List<MatOfPoint> contours = new java.util.ArrayList<MatOfPoint>();
    Mat hierarchy = new Mat();
    Imgproc.findContours(dst, contours, hierarchy, Imgproc.RETR_EXTERNAL, Imgproc.CHAIN_APPROX_SIMPLE,
        new Point(0, 0));
    System.out.println(contours.size());
    for (int i = 0; i < contours.size(); i++)
    {
      Imgproc.drawContours(src, contours, i, new Scalar(0, 0, 0, 0), 1);
    }
 
    Imgcodecs.imwrite("F:\\test.jpg", src);
  }