一个去除视频前景,保留背景的 opencv 小程序 (附注释)

/*
*  这是从网络上的一个获取背景的小程序.
*  程序运行后,从视频或者摄像头不断的获取图片,
*  并从动态图片中去除动态部分, 只保留背景(静态部分).
*  原程序只处理单色灰度图. 本人改为处理RGB彩色图.
*/

#include 

#include 
#include 
#include 

int main( int argc, char** argv )
{
	//声明IplImage图像指针
	IplImage* pFrame = NULL; 
	IplImage* pFrameBK = NULL; 
	IplImage* pFrameFG = NULL; 
	IplImage* pFrImgR = NULL;
	IplImage* pFrImgG = NULL;
	IplImage* pFrImgB = NULL;
	IplImage* pBkImgR = NULL;
	IplImage* pBkImgG = NULL;
	IplImage* pBkImgB = NULL;

	//声明CvMat矩阵指针。用于处理RGB三个通道数据.
	CvMat* pFrameMatR = NULL;
	CvMat* pFrameMatG = NULL;
	CvMat* pFrameMatB = NULL;
	CvMat* pFrMatR = NULL;
	CvMat* pFrMatG = NULL;
	CvMat* pFrMatB = NULL;
	CvMat* pBkMatR = NULL;
	CvMat* pBkMatG = NULL;
	CvMat* pBkMatB = NULL;

	//"black box" capture structure 
	CvCapture* pCapture = NULL;

	// 帧序号
	int nFrmNum = 0;

	cvNamedWindow("video", 1);
	cvNamedWindow("background",1);
	cvNamedWindow("foreground",1);
	//使窗口有序排列
	cvMoveWindow("video", 30, 0);
	cvMoveWindow("background", 360, 0);
	cvMoveWindow("foreground", 690, 0);



	if( argc > 2 )
	{
		fprintf(stderr, "Usage: bkgrd [video_file_name]\n");
		fprintf(stderr, "Usage: bkgrd\n");
		return -1;
	}

	//打开摄像头，原型：IplImage* cvQueryFrame( CvCapture* capture )\
	函数cvQueryFrame从摄像头或者文件中抓取一帧，\
	然后解压并返回这一帧。\
	这个函数仅仅是函数cvGrabFrame和函数cvRetrieveFrame在一起调用的组合。\
	返回的图像不可以被用户释放或者修改。

	if (argc ==1)
		if( !(pCapture = cvCaptureFromCAM(-1)))
		{
			fprintf(stderr, "Can not open camera.\n");
			return -2;
		}

		//打开视频文件
	if(argc == 2)
		if( !(pCapture = cvCaptureFromFile(argv[1])))
		{
			fprintf(stderr, "Can not open video file %s\n", argv[1]);
			return -2;
		}

		try
		{			
			//逐帧读取视频
			while(pFrame = cvQueryFrame( pCapture ))
			{
				nFrmNum++;

				//如果是第一帧，需要申请内存，并初始化，初始化需要的是（cvSize(宽高)，颜色深度，通道数）
				if(nFrmNum == 1)
				{
					pFrameBK = cvCreateImage(cvSize(pFrame->width, pFrame->height), IPL_DEPTH_8U,pFrame->nChannels);
					pFrameFG = cvCreateImage(cvSize(pFrame->width, pFrame->height), IPL_DEPTH_8U,pFrame->nChannels);
					pBkImgR = cvCreateImage(cvSize(pFrame->width, pFrame->height), IPL_DEPTH_8U,1);
					pBkImgG = cvCreateImage(cvSize(pFrame->width, pFrame->height), IPL_DEPTH_8U,1);
					pBkImgB = cvCreateImage(cvSize(pFrame->width, pFrame->height), IPL_DEPTH_8U,1);
					pFrImgR = cvCreateImage(cvSize(pFrame->width, pFrame->height), IPL_DEPTH_8U,1);
					pFrImgG = cvCreateImage(cvSize(pFrame->width, pFrame->height), IPL_DEPTH_8U,1);
					pFrImgB = cvCreateImage(cvSize(pFrame->width, pFrame->height), IPL_DEPTH_8U,1);
        
					//初始化矩阵
					pBkMatR = cvCreateMat(pFrame->height, pFrame->width, CV_32FC1);
					pBkMatG = cvCreateMat(pFrame->height, pFrame->width, CV_32FC1);
					pBkMatB = cvCreateMat(pFrame->height, pFrame->width, CV_32FC1);
					pFrMatR = cvCreateMat(pFrame->height, pFrame->width, CV_32FC1);
					pFrMatG = cvCreateMat(pFrame->height, pFrame->width, CV_32FC1);
					pFrMatB = cvCreateMat(pFrame->height, pFrame->width, CV_32FC1);
					pFrameMatR = cvCreateMat(pFrame->height, pFrame->width, CV_32FC1);
					pFrameMatG = cvCreateMat(pFrame->height, pFrame->width, CV_32FC1);
					pFrameMatB = cvCreateMat(pFrame->height, pFrame->width, CV_32FC1);

					//RGB图像分离成单通道图像再处理
					cvSplit(pFrame, pBkImgR, pBkImgG, pBkImgB, 0);
					cvSplit(pFrame, pFrImgR, pFrImgG, pFrImgB, 0);

					cvConvert(pFrImgR, pFrameMatR);
					cvConvert(pFrImgG, pFrameMatG);
					cvConvert(pFrImgB, pFrameMatB);
					cvConvert(pFrImgR, pFrMatR);
					cvConvert(pFrImgG, pFrMatG);
					cvConvert(pFrImgB, pFrMatB);
					cvConvert(pFrImgR, pBkMatR);
					cvConvert(pFrImgG, pBkMatG);
					cvConvert(pFrImgB, pBkMatB);
				}
				else
				{
					cvSplit(pFrame, pFrImgR, pFrImgG, pFrImgB, 0);
					cvConvert(pFrImgR, pFrameMatR);
					cvConvert(pFrImgG, pFrameMatG);
					cvConvert(pFrImgB, pFrameMatB);

					//当前帧跟背景图相减
					cvAbsDiff(pFrameMatR, pBkMatR, pFrMatR);
					cvAbsDiff(pFrameMatG, pBkMatG, pFrMatG);
					cvAbsDiff(pFrameMatB, pBkMatB, pFrMatB);

					//二值化前景图
					cvThreshold(pFrMatR, pFrImgR, 60, 255.0, CV_THRESH_BINARY);
					cvThreshold(pFrMatG, pFrImgG, 60, 255.0, CV_THRESH_BINARY);
					cvThreshold(pFrMatB, pFrImgB, 60, 255.0, CV_THRESH_BINARY);

					//更新背景
					cvRunningAvg(pFrameMatR, pBkMatR, 0.003, 0);
					cvRunningAvg(pFrameMatG, pBkMatG, 0.003, 0);
					cvRunningAvg(pFrameMatB, pBkMatB, 0.003, 0);
					//将背景转化为图像格式，用以显示
					cvConvert(pBkMatR, pBkImgR);
					cvConvert(pBkMatG, pBkImgG);
					cvConvert(pBkMatB, pBkImgB);

					cvMerge(pBkImgR, pBkImgG, pBkImgB, 0, pFrameBK);
					cvMerge(pFrImgR, pFrImgG, pFrImgB, 0, pFrameFG);

					//显示图像
					cvShowImage("video", pFrame);
					cvShowImage("background", pFrameBK);
					cvShowImage("foreground", pFrameFG);

					//如果有按键事件，则跳出循环
					if( cvWaitKey(2) >= 0 )
						break;

				}

			}
		}
		catch(cv::Exception& e)
		{
			std::cout<