MHI ,运动历史图像的的获取[下载自CSDN]

#include "cv.h"
#include "highgui.h"
#include "stdlib.h"
#include "malloc.h"
#include "cxcore.h"
#include "assert.h"
#include <time.h>
#include <math.h>
#include <ctype.h>
#include <stdio.h>
#include <iostream>

using namespace std;

// various tracking parameters (in seconds)
const double MHI_DURATION = 1;
const double MAX_TIME_DELTA = 0.5;
const double MIN_TIME_DELTA = 0.05;
// number of cyclic frame buffer used for motion detection
// (should, probably, depend on FPS)
//用于运动检测的循环帧数
const int N = 4;

// ring image buffer
IplImage **buf = 0;
int last = 0;

// temporary images
IplImage *mhi = 0; // MHI
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 = (double)clock() / CLOCKS_PER_SEC; // 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  为图像分配初始空间
    // reallocate them if the frame size is changed  当帧的大小改变时，重新分配内存空间
    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]));//把申请到的内存空间用0初始化
        }

        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 转换为灰度图

    idx2 = (last + 1) % N; // index of (last - (N-1))th frame
    last = idx2;
    silh = buf[idx2];
    cvAbsDiff(buf[idx1], buf[idx2], silh); // get difference between frames相邻两帧之差

    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(mhi, mask, 255. / MHI_DURATION,
        (MHI_DURATION - timestamp)*255. / MHI_DURATION);
    cvZero(dst);
    cvCvtPlaneToPix(mask, 0, 0, 0, dst);

    // calculate motion gradient orientation and valid orientation mask计算运动的梯度方向以及正确的方向掩码
    cvCalcMotionGradient(mhi, mask, orient, MAX_TIME_DELTA, MIN_TIME_DELTA, 3);

    if (!storage)
        storage = cvCreateMemStorage(0);
    else
        cvClearMemStorage(storage);

    // segment motion: get sequence of motion components运动分割:获取运动组成成分的序列
    // 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,迭代运动的组成成分
    // One more iteration (i == -1) corresponds to the whole image (global motion)
    for (i = -1; i < seq->total; i++)
    {

        if (i < 0)
        { // case of the whole image
            comp_rect = cvRect(0, 0, size.width, size.height);
            color = CV_RGB(255, 255, 255);
            magnitude = 100;
        }
        else
        { // i-th motion component
            comp_rect = ((CvConnectedComp*)cvGetSeqElem(seq, i))->rect;
            if (comp_rect.width + comp_rect.height < 100) // reject very small components
                continue;
            color = CV_RGB(255, 0, 0);
            magnitude = 30;
        }

        // select component ROI
        cvSetImageROI(silh, comp_rect);
        cvSetImageROI(mhi, comp_rect);
        cvSetImageROI(orient, comp_rect);
        cvSetImageROI(mask, comp_rect);

        // calculate orientation在选择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

        count = cvNorm(silh, 0, CV_L1, 0); // calculate number of points within silhouette 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)
            continue;

        //// draw a clock with arrow indicating the direction画一个“钟表”指向运动的方向
        //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;

    capture = cvCaptureFromFile("E:\Videos\\daria_walk.avi");

    if (capture)
    {
        cvNamedWindow("Motion", 1);

        for (;;)
        {
            IplImage* image;
            if (!cvGrabFrame(capture))
                break;
            //Decodes and returns the grabbed video frame.
            //C++: bool VideoCapture::retrieve(Mat& image, int channel=0)
            // IplImage* cvRetrieveFrame(CvCapture* capture, int streamIdx=0 )
            image = cvRetrieveFrame(capture);

            if (image)
            {
                if (!motion)
                {
                    //Creates an image header and allocates the image data.
                    //C: IplImage* cvCreateImage(CvSize size, int depth, int channels)
                    motion = cvCreateImage(cvSize(image->width, image->height), 8, 3);
                    //Clears the array.
                    //C: void cvSetZero(CvArr* arr)
                    cvZero(motion);
                    motion->origin = image->origin;
                }
            }

            update_mhi(image, motion, 30);
            cvShowImage("Motion", motion);

            if (cvWaitKey(10) >= 0)
                break;
        }
        cvReleaseCapture(&capture);
        cvDestroyWindow("Motion");
    }

    return 0;
    
}