OpenCv学习笔记（七）：轮廓的检测

其实要说轮廓的检测，是计算机视觉当中基础的内容，进一步延伸可以用来实现基于轮廓的图像检索。现在是刚看到的一段代码，通知canny算子实现轮廓的检测，特别用到了opencv当中的findContours函数，及drawContours函数实现轮廓的绘制。学习实例源代码如下：

#include "stdafx.h"

/**

* @function findContours_Demo.cpp

* @brief Demo code to find contours in an image

* @author OpenCV team

*/

#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 header

void thresh_callback(int, void* );

/**

* @function main

*/

int main( int argc, char** argv )

{

/// Load source image and convert it to gray

src = imread( "d:/2.jpg", 1 );

/// Convert image to gray and blur it

cvtColor( src, src_gray, CV_BGR2GRAY );

blur( src_gray, src_gray, Size(3,3) );

/// Create Window

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;

/// Detect edges using canny

Canny( src_gray, canny_output, thresh, thresh*2, 3 );

/// Find contours

findContours( canny_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );

/// Draw contours

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() );

}

/// Show in a window

namedWindow( "Contours", CV_WINDOW_AUTOSIZE );

imshow( "Contours", drawing );

}