OpenCV如何提取图片中曲线

//寻找图像曲线上某个点的下一个点
bool findNextPoint(vector<Point> &_neighbor_points, Mat &_image, Point _inpoint, int flag, Point& _outpoint, int &_outflag)
{
 int i = flag;
 int count = 1;
 bool success = false;

 while (count <= 7)
 {
  Point tmppoint = _inpoint + _neighbor_points[i];
  if (tmppoint.x > 0 && tmppoint.y > 0 && tmppoint.x < _image.cols&&tmppoint.y < _image.rows)
  {
   if (_image.at<uchar>(tmppoint) == 255)
   {
    _outpoint = tmppoint;
    _outflag = i;
    success = true;
    _image.at<uchar>(tmppoint) = 0;
    break;
   }
  }
  if (count % 2)
  {
   i += count;
   if (i > 7)
   {
    i -= 8;
   }
  }
  else
  {
   i += -count;
   if (i < 0)
   {
    i += 8;
   }
  }
  count++;
 }
 return success;
}
//寻找图像上的第一个点
bool findFirstPoint(Mat &_inputimg, Point &_outputpoint)
{
 bool success = false;
 for (int i = 0; i < _inputimg.rows; i++)
 {
  uchar* data = _inputimg.ptr<uchar>(i);
  for (int j = 0; j < _inputimg.cols; j++)
  {
   if (data[j] == 255)
   {
    success = true;
    _outputpoint.x = j;
    _outputpoint.y = i;
    data[j] = 0;
    break;
   }
  }
  if (success)
   break;
 }
 return success;
}
//寻找曲线 
void findLines(Mat &_inputimg, vector<deque<Point>> &_outputlines)
{
 vector<Point> neighbor_points = { Point(-1,-1),Point(0,-1),Point(1,-1),Point(1,0),Point(1,1),Point(0,1),Point(-1,1),Point(-1,0) };
 Point first_point;
 while (findFirstPoint(_inputimg, first_point))
 {
  deque<Point> line;
  line.push_back(first_point);
  //由于第一个点不一定是线段的起始位置，双向找
  Point this_point = first_point;
  int this_flag = 0;
  Point next_point;
  int next_flag;
  while (findNextPoint(neighbor_points, _inputimg, this_point, this_flag, next_point, next_flag))
  {
   line.push_back(next_point);
   this_point = next_point;
   this_flag = next_flag;
  }
  //找另一边
  this_point = first_point;
  this_flag = 0;
  //cout << "flag:" << this_flag << endl;
  while (findNextPoint(neighbor_points, _inputimg, this_point, this_flag, next_point, next_flag))
  {
   line.push_front(next_point);
   this_point = next_point;
   this_flag = next_flag;
  }
  if (line.size() > 10)
  {
   _outputlines.push_back(line);
  }
 }
}
//随机取色 用于画线的时候
Scalar random_color(RNG& _rng)
{
 int icolor = (unsigned)_rng;
 return Scalar(icolor & 0xFF, (icolor >> 8) & 0xFF, (icolor >> 16) & 0xFF);
}
int main()
{
 Mat image = imread("images\\2.bmp");
 Mat gray;
 cvtColor(image, gray, CV_BGR2GRAY);
 vector<deque<Point>> lines;
 findLines(gray, lines);
 cout << lines.size() << endl;
 //draw lines
 Mat draw_img = image.clone();
 RNG rng(123);
 Scalar color;
 for (int i = 0; i < lines.size(); i++)
 {
  color = random_color(rng);
  for (int j = 0; j < lines[i].size(); j++)
  {
   draw_img.at<Vec3b>(lines[i][j]) = Vec3b(color[0], color[1], color[2]);
  }
 }
 imshow("draw_img", draw_img);
 imwrite("images\\draw_img.bmp", draw_img);
 waitKey(0);
 system("pause");
 return 0;
}