[Java] 使用java + OpenCV破解顶象面积验证码的示例

那么我们把它拆分成以下几个步骤：
检测出图中标记的点将检测出来的点连成线根据线分割出的区域计算各区域面积，并得到最大面积在该区域面积中选取一个坐标点作为结果

/**
   * 哈里斯角点检测
   * @param img   原图地址
   * @param img2  新图地址
   */
  public void getHarris(String img,String img2) {
    System.load(dllPath);
    File bFile = new File(img);
    try {
      Mat mat = Imgcodecs.imread(bFile.getPath());
      // 转灰度图像
      Mat gray = new Mat();
      Imgproc.cvtColor(mat, gray, Imgproc.COLOR_BGR2GRAY);
      // 角点发现
      Mat harris = new Mat();
      Imgproc.cornerHarris(gray, harris, 2, 3, 0.04);
      // 绘制角点
      float[] floats = new float[harris.cols()];
      for (int i = 0; i < harris.rows(); i++) {
        harris.get(i, 0, floats);
        for (int j = 0; j < floats.length; j++) {
          if (floats[j] > 0.0001) {// 越接近于角点数值越大
            System.out.println(floats[j]);
            Imgproc.circle(mat, new Point(j, i), 1, new Scalar(0, 255, 0));
          }
        }
      }
      Imgcodecs.imwrite(img2, mat);
    } catch (Throwable e) {
      e.printStackTrace();
    }
  }

Imgproc.circle(mat, new Point(j, i), 5, new Scalar(0, 255, 0));

/**根据线分割出的区域计算各区域面积，并得到最大面积
   * @param oldimg 原图
   * @param newimg 绘制角点后的图
   */
   */
  public void getMatrix(String oldimg,String newimg) {
    File ofile = new File(oldimg);
    File nfile = new File(newimg);
    try {
      BufferedImage oimage = ImageIO.read(ofile);
      BufferedImage nimage = ImageIO.read(nfile);
      int matrix[][] = new int[nimage.getWidth()][nimage.getHeight()];
      int rank = 0;
      int maxRank = 0;
      int count = 0;
      int maxCount = 0;
      //将检测并高亮部分置1，其余部分置0，得到一个代替图的二维数组
      for (int w = 0; w < nimage.getWidth(); w++) {
        for (int h = 0; h < nimage.getHeight(); h++) {
          int[] bgRgb = new int[3];
          bgRgb[0] = (nimage.getRGB(w, h) & 0xff0000) >> 16;
          bgRgb[1] = (nimage.getRGB(w, h) & 0xff00) >> 8;
          bgRgb[2] = (nimage.getRGB(w, h) & 0xff);
          if (!(bgRgb[0] <= 70 && bgRgb[1] >= 180 && bgRgb[2] <= 70)) {
            matrix[w][h] = 0;
          } else {
            matrix[w][h] = -1;
          }
        }
      }
      //深度优先搜索找出最大区域
      while (true) {
        int n = 0;
        for (int i = 0; i < matrix.length; i++) {
          for (int j = 0; j < matrix[0].length; j++) {
            if (matrix[i][j] == 0) {
              n++;
              rank++;
              count = dfs(matrix, rank);
              if (count > maxCount) {
                maxCount = count;
                maxRank = rank;
              }
            }
          }
        }
        if (n == 0)
          break;
      }
      //改变最大区域颜色
      for (int j = 0; j < matrix[0].length; j++) {
        for (int i = 0; i < matrix.length; i++) {
          if (matrix[i][j] == maxRank){
            nimage.setRGB(i, j, new Color(0, 0, 255).getRGB());
          }
        }
      }
      ImageIO.write(image, "png", new File(img));
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
  /**
   * 深度优先搜索
   * @param matrix 图信息数组
   * @param n 标记数
   * @return
   */
  public int dfs(int matrix[][], int rank) {
    int count = 0;
    int w = -1;
    int h = -1;
    for (int i = 0; i < matrix.length; i++) {
      for (int j = 0; j < matrix[0].length; j++) {
        if (matrix[i][j] == 0) {
          w = i;
          h = j;
          break;
        }
      }
      if (w != -1) {
        break;
      }
    }
    Stack<JSONObject> stack = new Stack<JSONObject>();
    while (matrix[w][h] == 0 || h == stack.peek().getIntValue("h") && w == stack.peek().getIntValue("w")) {
      JSONObject json = new JSONObject();
      json.put("w", w);
      json.put("h", h);
      stack.push(json);
      matrix[w][h] = rank;
      count++;
      if (h + 1 < matrix[0].length) {
        if (matrix[w][h + 1] == 0) {
          h = h + 1;
          continue;
        }
      }
      if (w + 1 < matrix.length) {
        if (matrix[w + 1][h] == 0) {
          w = w + 1;
          continue;
        }
      }
      if (h - 1 >= 0) {
        if (matrix[w][h - 1] == 0) {
          h = h - 1;
          continue;
        }
      }
      if (w - 1 >= 0) {
        if (matrix[w - 1][h] == 0) {
          w = w - 1;
          continue;
        }
      }
      stack.pop();
      if (!stack.empty()) {
        if (h == stack.peek().getIntValue("h") && w == stack.peek().getIntValue("w")) {
          stack.pop();
        }
      }
      if (!stack.empty()) {
        w = stack.peek().getIntValue("w");
        h = stack.peek().getIntValue("h");
      } else {
        break;
      }
    }
    return count;
  }

//改变最大区域颜色
for (int j = 0; j < matrix[0].length; j++) {
  for (int i = 0; i < matrix.length; i++) {
    if (matrix[i][j] == maxRank){
      nimage.setRGB(i, j, new Color(0, 0, 255).getRGB());
    }
  }
}

//标记选取到的点
boolean flag = false;
for (int j = 0; j < matrix[0].length; j++) {
  for (int i = 0; i < matrix.length; i++) {
    if (matrix[i][j] == maxRank) {
      oimage.setRGB(i, j, new Color(255, 0, 0).getRGB());
      System.out.println("w=" + i + "|h=" + j);
      flag = true;
      break;
    }
  }
  if (flag) {
    break;
  }
}