视频前景提取 (III)【Mat版本】

这是(II)中的Mat版本，特别注意一下accumulateWeighted这个函数的用法。

我将官网文档中的函数表明贴起来：

accumulateWeighted

Updates a running average.

C++:voidaccumulateWeighted(InputArraysrc, InputOutputArraydst, doublealpha, InputArraymask=noArray())

Python:cv2.accumulateWeighted(src, dst, alpha[, mask])→ None

C:voidcvRunningAvg(const CvArr*image, CvArr*acc, doublealpha, const CvArr*mask=NULL)

Python:cv.RunningAvg(image, acc, alpha, mask=None)→ None

Parameters:

The function calculates the weighted sum of the input imagesrcand the accumulatordstso thatdstbecomes a running average of a frame sequence:

That is,alpharegulates the update speed (how fast the accumulator “forgets” about earlier images). The function supports multi-channel images. Each channel is processed independently.

See also

,,

代码：

//opencv2.0风格的视频前景提取
#include "cv.h"
#include "highgui.h"
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/core/core.hpp>
#include <iostream>
#include <cstdio>
using namespace std;
using namespace cv;
int main()
{
	Mat frame, frame_copy,img1,output,gray,frame_copy_8U;
	double learningRate = 0.01;	// 控制背景累积学习的速率
	char* input_name = "001.avi";
	//从视频读入
	VideoCapture capture(input_name);
	cvNamedWindow( "result", 1 );
	if(capture.isOpened()/*capture*/)	// 读取文件开关
	{
		//对每一帧做处理
		for(;;)
		{
			//frame = cvQueryFrame( capture );	// 读取文件开关
			capture >> frame;
			if(!frame.empty())
			{ 
				cvtColor(frame, gray, CV_BGR2GRAY);
				//进行处理
				if (frame_copy.empty())
				{
					//记录第一帧
					gray.convertTo(frame_copy, CV_32F);
				}
				frame_copy.convertTo(frame_copy_8U, CV_8U);
				//做差分
				absdiff(frame_copy_8U, gray, img1);
				// 对得到的前景进行阈值选取，去掉伪前景
				threshold(img1, output, 30, 255, THRESH_BINARY_INV);
				accumulateWeighted(gray, frame_copy,0.01,output);
				imshow("src", frame);
				imshow("result", output);
			}
			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;
}

更好版本(II)：

//opencv2.0风格的视频前景提取
#include "cv.h"
#include "highgui.h"
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/core/core.hpp>
#include <iostream>
#include <cstdio>
using namespace std;
using namespace cv;
int main()
{
	Mat frame, frame_copy,img1,output,gray,frame_copy_8U;
	double learningRate;	// 控制背景累积学习的速率
	int nThreshold; //二值化阈值
	char* input_name = "001.avi";
	//从视频读入
	VideoCapture capture(input_name);
	cvNamedWindow( "result", 1 );
	if(capture.isOpened()/*capture*/)	// 读取文件开关
	{
		//对每一帧做处理
		for(;;)
		{
			//frame = cvQueryFrame( capture );	// 读取文件开关
			capture >> frame;
			if(!frame.empty())
			{ 
				cvtColor(frame, gray, CV_BGR2GRAY);
				//进行处理
				if (frame_copy.empty())
				{
					//记录第一帧
					gray.convertTo(frame_copy, CV_32F);
				}
				frame_copy.convertTo(frame_copy_8U, CV_8U);
				//做差分
				absdiff(frame_copy_8U, gray, img1);
				// 对得到的前景进行阈值选取，去掉伪前景
				nThreshold=30;
				threshold(img1, output, nThreshold, 255, THRESH_BINARY_INV);
				learningRate = 0.01;
				accumulateWeighted(gray, frame_copy,learningRate,output);
				imshow("src", frame);
				imshow("result", output);
			}
			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;
}

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