在图像中寻找轮廓

目标

在这个教程中你将学到如何:

• 使用OpenCV函数 findContours
• 使用OpenCV函数 drawContours

原理

例程

教程的代码在下面给出. 你也可以从 这里 下载

#include "opencv2/highgui/highgui.hpp"#include "opencv2/imgproc/imgproc.hpp"#include <iostream>#include <stdio.h>#include <stdlib.h>using namespace cv;using namespace std;Mat src; Mat src_gray;int thresh = 100;int max_thresh = 255;RNG rng(12345);/// Function headervoid thresh_callback(int, void* );/** @function main */int main( int argc, char** argv ){  /// 加载源图像  src = imread( argv[1], 1 );  /// 转成灰度并模糊化降噪  cvtColor( src, src_gray, CV_BGR2GRAY );  blur( src_gray, src_gray, Size(3,3) );  /// 创建窗体  char* source_window = "Source";  namedWindow( source_window, CV_WINDOW_AUTOSIZE );  imshow( source_window, src );  createTrackbar( " Canny thresh:", "Source", &thresh, max_thresh, thresh_callback );  thresh_callback( 0, 0 );  waitKey(0);  return(0);}/** @function thresh_callback */void thresh_callback(int, void* ){  Mat canny_output;  vector<vector<Point> > contours;  vector<Vec4i> hierarchy;  /// 用Canny算子检测边缘  Canny( src_gray, canny_output, thresh, thresh*2, 3 );  /// 寻找轮廓  findContours( canny_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );  /// 绘出轮廓  Mat drawing = Mat::zeros( canny_output.size(), CV_8UC3 );  for( int i = 0; i< contours.size(); i++ )     {       Scalar color = Scalar( rng.uniform(0, 255), rng.uniform(0,255), rng.uniform(0,255) );       drawContours( drawing, contours, i, color, 2, 8, hierarchy, 0, Point() );     }  /// 在窗体中显示结果  namedWindow( "Contours", CV_WINDOW_AUTOSIZE );  imshow( "Contours", drawing );}

例程说明

结果

1. 原图和检测到的轮廓如下: