源代码：
#include "cv.h"
#include "highgui.h"
#include
#include
#include
#include
// various tracking parameters (in seconds)
const double MHI_DURATION = 0.5;
const double MAX_TIME_DELTA = 0.5;
const double MIN_TIME_DELTA = 0.05;
// 用于运动检测的循环帧数，与机器速度以及FPS设置有关
const int N = 2;
// ring image buffer
IplImage **buf = 0;
int last = 0;
// temporary images
IplImage *mhi = 0; // MHI: motion history image
IplImage *orient = 0; // orientation
IplImage *mask = 0; // valid orientation mask
IplImage *segmask = 0; // motion segmentation map
CvMemStorage* storage = 0; // temporary storage
// parameters:
// img - input video frame
// dst - resultant motion picture
// args - optional parameters
void update_mhi( IplImage* img, IplImage* dst, int diff_threshold )
{
double timestamp = clock()/1000.; // get current time in seconds
CvSize size = cvSize(img->width,img->height); // get current frame size
int i, idx1 = last, idx2;
IplImage* silh;
CvSeq* seq;
CvRect comp_rect;
double count;
double angle;
CvPoint center;
double magnitude;
CvScalar color;
// allocate images at the beginning or
// reallocate them if the frame size is changed
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 );
cvReleaseImage( &orient );
cvReleaseImage( &segmask );
cvReleaseImage( &mask );
mhi = cvCreateImage( size, IPL_DEPTH_32F, 1 );
cvZero( mhi ); // clear MHI at the beginning
orient = cvCreateImage( size, IPL_DEPTH_32F, 1 );
segmask = cvCreateImage( size, IPL_DEPTH_32F, 1 );
mask = cvCreateImage( size, IPL_DEPTH_8U, 1 );
}
cvCvtColor( img, buf[last], CV_BGR2GRAY ); // convert frame to grayscale
idx2 = (last + 1) % N; // index of (last - (N-1))th frame
last = idx2;
silh = buf[idx2];
// 相邻两帧的差
cvAbsDiff( buf[idx1], buf[idx2], silh ); // get difference between frames
// 对差图像做二值化
cvThreshold( silh, silh, diff_threshold, 1, CV_THRESH_BINARY ); // and threshold it
cvUpdateMotionHistory( silh, mhi, timestamp, MHI_DURATION ); // update MHI
// convert MHI to blue 8u image
// cvCvtScale的第四个参数 shift = (MHI_DURATION - timestamp)*255./MHI_DURATION
// 控制帧差的消失速率
cvCvtScale( mhi, mask, 255./MHI_DURATION,
(MHI_DURATION - timestamp)*255./MHI_DURATION );
cvZero( dst );
cvCvtPlaneToPix(mask, 0, 0, 0, dst ); // B,G,R,0 －> dist : convert to BLUE image
// 计算运动的梯度方向以及正确的方向掩模mask
// Filter size = 3
cvCalcMotionGradient( mhi, mask, orient,
MAX_TIME_DELTA, MIN_TIME_DELTA, 3 );
if( !storage )
storage = cvCreateMemStorage(0);
else
cvClearMemStorage(storage);
// 运动分割: 获得运动部件的连续序列
// segmask is marked motion components map. It is not used further
seq = cvSegmentMotion( mhi, segmask, storage, timestamp, MAX_TIME_DELTA );
// iterate through the motion components,
// One more iteration (i == -1) corresponds to the whole image (global motion)
for( i = 0; i < seq->total; i++ )
{
if( i < 0 ) { // case of the whole image，对整幅图像做操作
comp_rect = cvRect( 0, 0, size.width, size.height );
color = CV_RGB(255,255,255); // white color
magnitude = 100; // 画线长度以及圆半径的大小控制
}
else { // i-th motion component
comp_rect = ((CvConnectedComp*)cvGetSeqElem( seq, i ))->rect;
// 去掉小的部分
if( comp_rect.width + comp_rect.height < 100 )
continue;
color = CV_RGB(255,0,0); // red color
magnitude = 30;
//if(seq->total > 0) MessageBox(NULL,"Motion Detected",NULL,0);
}
// select component ROI
cvSetImageROI( silh, comp_rect );
cvSetImageROI( mhi, comp_rect );
cvSetImageROI( orient, comp_rect );
cvSetImageROI( mask, comp_rect );
// 在选择的区域内, 计算运动方向
angle = cvCalcGlobalOrientation( orient, mask, mhi, timestamp,
MHI_DURATION);
angle = 360.0 - angle; // adjust for images with top-left origin
// 在轮廓内计算点数
// Norm(L1) = sum of total pixel values
count = cvNorm( silh, 0, CV_L1, 0 );
// The function cvResetImageROI releases image ROI
cvResetImageROI( mhi );
cvResetImageROI( orient );
cvResetImageROI( mask );
cvResetImageROI( silh );
// check for the case of little motion
if( count < comp_rect.width*comp_rect.height * 0.05 ) // five percent of pixel
continue;
// draw a clock with arrow indicating the direction
center = cvPoint( (comp_rect.x + comp_rect.width/2),
(comp_rect.y + comp_rect.height/2) );
cvCircle( dst, center, cvRound(magnitude*1.2), color, 3, CV_AA, 0 );
cvLine( dst, center, cvPoint( cvRound( center.x +
magnitude*cos(angle*CV_PI/180)),
cvRound( center.y - magnitude*sin(angle*CV_PI/180))),
color, 3, CV_AA, 0 );
}
}
int main(int argc, char** argv)
{
IplImage* motion = 0;
CvCapture* capture = 0;
if( argc == 1 || (argc == 2 && strlen(argv[1]) == 1 && isdigit(argv[1][0])))
capture = cvCaptureFromCAM( argc == 2 ? argv[1][0] - '0' : 0 );
else if( argc == 2 )
capture = cvCaptureFromAVI( argv[1] );
if( capture )
{
cvNamedWindow( "Motion", 1 );
for(;;)
{
IplImage* image;
if( !cvGrabFrame( capture ))
break;
image = cvRetrieveFrame( capture );
if( image )
{
if( !motion )
{
motion = cvCreateImage( cvSize(image->width,image->height),
8, 3 );
cvZero( motion );
motion->origin = image->origin;
}
}
update_mhi( image, motion, 60 );
cvShowImage( "Motion", motion );
if( cvWaitKey(10) >= 0 )
break;
}
cvReleaseCapture( &capture );
cvDestroyWindow( "Motion" );
}
return 0;
}
