取出视频中有移动物体的帧

实用小程序：

//opencv2.0风格

//本程序有几个可调值
//1.背景更新 学习率 learningRate
//2.去掉小面积阈值 area_threshold

#include "cv.h"
#include "highgui.h"
#include <stdlib.h>

#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/core/core.hpp>

#include <iostream>
#include <string>
#include <cstdio>

using namespace std;
using namespace cv;

char input_name[50];
char outFolder[50];
char countChar[10000];
char tmp[50];


int main()
{
	//可调参数
	//char* input_name = "007.avi";
	double fScale = 0.5;      //缩放倍数
	double learningRate=0.5;    // 控制背景累积学习的速率
	double area_threshold = 30;  //区域面积大小阈值
	int nThreshold=30; //二值化阈值


	Mat frame_ori;		//每一帧原图像，绝不处理
	Mat frame;		//每一帧图像处理
	Mat gray;		//frame转成的灰度图
	Mat frame_copy_8U;	//copy过来的8U图像
	Mat frame_copy;
	Mat img1;		//差分输出
	Mat outBinary; //二值图输出

	//输入
	cout<<"please input the src video :"<<endl;
	cin>>input_name;
	cout<<"please input the output folder :"<<endl;
	cin>>outFolder;

	//从视频读入
	VideoCapture capture(input_name);

	int count=0;
	if(capture.isOpened()/*capture*/)	//读取文件开关
	{
		//对每一帧做处理

		for(;;)
		{

			//单帧处理

			capture >> frame_ori;
			if(!frame_ori.empty())//如果捕捉到了
			{
				cout<<"\n\n***************New Start********************"<<endl;


				//将原图像缩放
				//resize(frame_ori,frame,Size(frame_ori.cols * fScale,frame_ori.rows * fScale),0,0,CV_INTER_LINEAR);
				frame=frame_ori;

				//frame->gray 单通道灰度图
				cvtColor(frame, gray, CV_BGR2GRAY);

				//进行处理
				if (frame_copy.empty())
				{
					//记录第一帧 gray->frame_copy
					gray.convertTo(frame_copy, CV_32F);
				}

				frame_copy.convertTo(frame_copy_8U, CV_8U);
				//差分
				absdiff(frame_copy_8U, gray, img1);


				//二值化
				threshold(img1, outBinary, nThreshold, 255, THRESH_BINARY);

				accumulateWeighted(gray, frame_copy,learningRate,outBinary);


				//加一个中值滤波，会减少不少误差
				cv::medianBlur(outBinary, outBinary,3);


				//轮廓检测
				vector<vector<Point>> _contours;//储存所有轮廓
				vector<Vec4i>hierarchy;

				Mat imageROI;;
				cv::findContours( outBinary, _contours, hierarchy, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE);

				int contoursSize=0;
				for(size_t i = 0; i< _contours.size(); ++i)
				{
					//遍历所有轮廓

					//计算轮廓面积
					double contArea =  fabs(contourArea(_contours[i]));

					//去除较小面积的轮廓
					if( contArea < area_threshold)
						continue;

					//获得外接矩形
					Rect r0 = boundingRect(Mat(_contours[i]));

					//实时画出每个矩形
					rectangle(outBinary,r0,cvScalar(255,255,255),1,8,0);

					contoursSize++;
				}

				cout<<"轮廓数 == "<<contoursSize<<endl;
				if(contoursSize!=0)
				{
					strcpy(countChar,outFolder);
					strcat(countChar,"\\");
					//cout<<countChar<<endl;
					//cout<<"有了有了！！！！！！！！"<<endl;
					count++;
					itoa(count,tmp,10);
					strcat(tmp,".jpg");
					strcat(countChar,tmp);
					//cout<<countChar<<endl;
					imwrite(countChar,frame_ori);
				}
				

				imshow("src", frame);
				imshow("outBinary", outBinary);
			}

			else
			{ 
				printf(" --(!) No captured frame -- Break!");
				break;
			}

			//10ms中按任意键进入此if块
			if( cvWaitKey( 10 ) >= 0 )
				break;
		}
	}

	return 0;
}