samples/cpp/segment_objects.cpp

一個使用 drawContours 清理背景分割結果的示例

#include "opencv2/imgproc.hpp"
#include "opencv2/videoio.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/video/background_segm.hpp"
#include <stdio.h>
#include <string>
 
using namespace std;
using namespace cv;
 
static void help(char** argv)
{
printf("\n"
            "此程式演示了一種使用連通元件清理背景減除的簡單方法\n"
            "程式啟動時，它開始學習背景。\n"
            "您可以透過按空格鍵來切換背景學習的開啟和關閉。\n"
            "呼叫\n"
            "%s [影片檔案，否則讀取攝像頭 0]\n\n", argv[0]);
}
 
static void refineSegments(const Mat& img, Mat& mask, Mat& dst)
{
    int niters = 3;
 
vector<vector<Point> > contours;
vector<Vec4i> hierarchy;
 
    Mat temp;
 
dilate(mask, temp, Mat(), Point(-1,-1), niters);
erode(temp, temp, Mat(), Point(-1,-1), niters*2);
dilate(temp, temp, Mat(), Point(-1,-1), niters);
 
findContours( temp, contours, hierarchy, RETR_CCOMP, CHAIN_APPROX_SIMPLE );
 
dst = Mat::zeros(img.size(), CV_8UC3);
 
    if( contours.size() == 0 )
        return;
 
    // 迭代所有頂層輪廓，
    // 用其自己的隨機顏色繪製每個連線的元件
    int idx = 0, largestComp = 0;
    double maxArea = 0;
 
    for( ; idx >= 0; idx = hierarchy[idx][0] )
    {
        const vector<Point>& c = contours[idx];
        double area = fabs(contourArea(Mat(c)));
        if( area > maxArea )
        {
maxArea = area;
largestComp = idx;
        }
    }
    Scalar color( 0, 0, 255 );
    drawContours( dst, contours, largestComp, color, FILLED, LINE_8, hierarchy );
}
 
 
int main(int argc, char** argv)
{
    VideoCapture cap;
    bool update_bg_model = true;
 
    CommandLineParser parser(argc, argv, "{help h||}{@input||}");
    if (parser.has("help"))
    {
help(argv);
        return 0;
    }
    string input = parser.get<std::string>("@input");
    if (input.empty())
cap.open(0);
    else
cap.open(samples::findFileOrKeep(input));
 
    if( !cap.isOpened() )
    {
printf("\n無法開啟攝像頭或影片檔案\n");
        return -1;
    }
 
    Mat tmp_frame, bgmask, out_frame;
 
cap >> tmp_frame;
    if(tmp_frame.empty())
    {
printf("無法從影片源讀取資料\n");
        return -1;
    }
 
    namedWindow("video", 1);
    namedWindow("segmented", 1);
 
    Ptr<BackgroundSubtractorMOG2> bgsubtractor=createBackgroundSubtractorMOG2();
bgsubtractor->setVarThreshold(10);
 
    for(;;)
    {
cap >> tmp_frame;
        if( tmp_frame.empty() )
            break;
bgsubtractor->apply(tmp_frame, bgmask, update_bg_model ? -1 : 0);
refineSegments(tmp_frame, bgmask, out_frame);
        imshow("video", tmp_frame);
        imshow("segmented", out_frame);
        char keycode = (char)waitKey(30);
        if( keycode == 27 )
            break;
        if( keycode == ' ' )
        {
update_bg_model = !update_bg_model;
printf("學習背景狀態 = %d\n",update_bg_model);
        }
    }
 
    return 0;
}