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//
// CVFMotionTemplates.m
// CVFunhouse
//
// Created by John Brewer on 7/25/12.
// Copyright (c) 2012 Jera Design LLC. All rights reserved.
//
// Based on the OpenCV example: <opencv>/samples/c/motempl.c
#import "CVFMotionTemplates.h"
#include "opencv2/video/tracking.hpp"
#include "opencv2/imgproc/imgproc_c.h"
// 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)
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
static 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
// 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];
cvAbsDiff( buf[idx1], buf[idx2], silh ); // get difference between frames
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 );
cvMerge( mask, 0, 0, 0, dst );
// calculate motion gradient orientation and valid orientation mask
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
// 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++ ) {
comp_rect = ((CvConnectedComp*)cvGetSeqElem( seq, i ))->rect;
if( comp_rect.width + comp_rect.height < 200 ) // 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
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
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 );
}
}
@interface CVFMotionTemplates () {
IplImage* motion;
}
@end
@implementation CVFMotionTemplates
/*
* processIplImage
*
* Inputs:
* iplImage: an IplImage in BGRA format, 8 bits per pixel.
* YOU ARE RESPONSIBLE FOR CALLING cvReleaseImage on this image.
*
* Outputs:
* When you are done, call imageReady: with an RGB, RGBA, or grayscale
* IplImage with 8-bits per pixel.
*
* You can call imageReady: from any thread and it will do the right thing.
* You can fork as many threads to process the image as you like; just call
* imageReady when you are done.
*
* imageReady: will dispose of the IplImage you pass it once the system is
* done with it.
*/
-(void)processIplImage:(IplImage*)image
{
if( !motion )
{
motion = cvCreateImage( cvSize(image->width,image->height), 8, 3 );
cvZero( motion );
motion->origin = image->origin;
}
update_mhi( image, motion, 30 );
cvReleaseImage(&image);
// Call imageReady with your new image.
IplImage *outImage = cvCloneImage(motion);
[self imageReady:outImage];
}
@end