OpenCV实现运动目标检测的函数

// 参数：

// img – 输入视频帧

// dst – 检测结果

void update_mhi( IplImage* img, IplImage* dst, int diff_threshold )

{

double timestamp = clock()/100.; // get current time in seconds

CvSize size = cvSize(img->width,img->height); // get current frame size

int i, j, idx1, idx2;

IplImage* silh;

uchar val;

float temp;

IplImage* pyr = cvCreateImage( cvSize((size.width & -2)/2, (size.height & -2)/2), 8, 1 );

CvMemStorage *stor;

CvSeq *cont, *result, *squares;

CvSeqReader reader;

if( !mhi || mhi->width != size.width || mhi->height != size.height )

{

if( buf == 0 )

{

buf = (IplImage**)malloc(N*sizeof(buf[0]));

memset( buf, 0, N*sizeof(buf[0]));

}

for( i = 0; i < N; i++ )

{

cvReleaseImage( &buf[i] );

buf[i] = cvCreateImage( size, IPL_DEPTH_8U, 1 );

cvZero( buf[i] );

}

cvReleaseImage( &mhi );

mhi = cvCreateImage( size, IPL_DEPTH_32F, 1 );

cvZero( mhi ); // clear MHI at the beginning

} // end of if(mhi)

cvCvtColor( img, buf[last], CV_BGR2GRAY ); // convert frame to grayscale

idx1 = last;

idx2 = (last + 1) % N; // index of (last - (N-1))th frame

last = idx2;

// 做帧差

silh = buf[idx2];

cvAbsDiff( buf[idx1], buf[idx2], silh ); // get difference between frames

// 对差图像做二值化

cvThreshold( silh, silh, 30, 255, CV_THRESH_BINARY ); // and threshold it

cvUpdateMotionHistory( silh, mhi, timestamp, MHI_DURATION ); // update MHI

cvCvtScale( mhi, dst, 255./MHI_DURATION,

(MHI_DURATION - timestamp)*255./MHI_DURATION );

cvCvtScale( mhi, dst, 255./MHI_DURATION, 0 );

// 中值滤波，消除小的噪声

cvSmooth( dst, dst, CV_MEDIAN, 3, 0, 0, 0 );

// 向下采样，去掉噪声

cvPyrDown( dst, pyr, 7 );

cvDilate( pyr, pyr, 0, 1 ); // 做膨胀操作，消除目标的不连续空洞

cvPyrUp( pyr, dst, 7 );

//

// 下面的程序段用来找到轮廓

//

// Create dynamic structure and sequence.

stor = cvCreateMemStorage(0);

cont = cvCreateSeq(CV_SEQ_ELTYPE_POINT, sizeof(CvSeq), sizeof(CvPoint) , stor);

// 找到所有轮廓

cvFindContours( dst, stor, &cont, sizeof(CvContour),

CV_RETR_LIST, CV_CHAIN_APPROX_SIMPLE, cvPoint(0,0));

/*

for(;cont;cont = cont->h_next)

{

// Number point must be more than or equal to 6 (for cvFitEllipse_32f).

if( cont->total < 6 )

continue;

// Draw current contour.

cvDrawContours(img,cont,CV_RGB(255,0,0),CV_RGB(255,0,0),0,1, 8, cvPoint(0,0));

} // end of for-loop: "cont"

*/

// 直接使用CONTOUR中的矩形来画轮廓

for(;cont;cont = cont->h_next)

{

CvRect r = ((CvContour*)cont)->rect;

if(r.height * r.width > CONTOUR_MAX_AERA) // 面积小的方形抛弃掉

{

cvRectangle( img, cvPoint(r.x,r.y),

cvPoint(r.x + r.width, r.y + r.height),

CV_RGB(255,0,0), 1, CV_AA,0);

}

}

// free memory

cvReleaseMemStorage(&stor);

cvReleaseImage( &pyr );

}