【opencv 450 Image Processing】查找轮廓Finding contours in your image

最新推荐文章于 2024-06-20 15:11:47 发布

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Goal

在本教程中，您将学习如何：

使用 OpenCV 函数 cv::findContours

使用 OpenCV 函数 cv::drawContours

Theory

Code

本教程代码如下所示。你也可以从这里下载opencv/findContours_demo.cpp at 4.x · opencv/opencv (github.com)

/**
 * @function findContours_Demo.cpp
 * @brief 在图像中查找轮廓的演示代码
 * @author OpenCV team
 */

#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/imgproc.hpp"
#include <iostream>

using namespace cv;
using namespace std;

Mat src_gray;//灰度图
int thresh = 100;//滑动条绑定的数值
RNG rng(12345);//随机数发生器

///函数头
void thresh_callback(int, void* );

/**
 * @function main
 */
int main( int argc, char** argv )
{
    /// 加载源图像
    CommandLineParser parser( argc, argv, "{@input | HappyFish.jpg | input image}" );
    Mat src = imread( samples::findFile( parser.get<String>( "@input" ) ) );
    if( src.empty() )
    {
      cout << "Could not open or find the image!\n" << endl;
      cout << "Usage: " << argv[0] << " <Input image>" << endl;
      return -1;
    }

    ///将图像转换为灰色并模糊它 Convert image to gray and blur it
    cvtColor( src, src_gray, COLOR_BGR2GRAY );
    blur( src_gray, src_gray, Size(3,3) );//均值滤波

    /// 创建窗口
    const char* source_window = "Source";
    namedWindow( source_window );
    imshow( source_window, src );//显示源图像

    const int max_thresh = 255;
    createTrackbar( "Canny thresh:", source_window, &thresh, max_thresh, thresh_callback );//滑动条 
    thresh_callback( 0, 0 );//回调函数

    waitKey();
    return 0;
}

/**
 * @function thresh_callback
 */
void thresh_callback(int, void* )
{
    ///使用 Canny 检测边缘 Detect edges using Canny
    Mat canny_output;
    Canny( src_gray, canny_output, thresh, thresh*2 );

    ///寻找轮廓
    vector<vector<Point> > contours;//轮廓点 向量
    vector<Vec4i> hierarchy;
    findContours( canny_output, contours, hierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE );

    /// 绘制轮廓
    Mat drawing = Mat::zeros( canny_output.size(), CV_8UC3 );//黑色背景图像
    for( size_t i = 0; i< contours.size(); i++ )
    {
        Scalar color = Scalar( rng.uniform(0, 256), rng.uniform(0,256), rng.uniform(0,256) );//随机颜色
        drawContours( drawing, contours, (int)i, color, 2, LINE_8, hierarchy, 0 );//黑色背景上绘制所有轮廓
    }

    ///在窗口显示 Show in a window
    imshow( "Contours", drawing );
}