static void cvTsMHIGradient( const CvMat* mhi, CvMat* mask, CvMat* orientation,
double delta1, double delta2, int aperture_size )
{
CvPoint anchor = { aperture_size/2, aperture_size/2 };
CvMat* src = cvCreateMat( mhi->rows + aperture_size - 1, mhi->cols + aperture_size - 1, CV_32FC1 );
CvMat* kernel = cvCreateMat( aperture_size, aperture_size, CV_32FC1 );
CvMat* dx = cvCreateMat( mhi->rows, mhi->cols, CV_32FC1 );
CvMat* dy = cvCreateMat( mhi->rows, mhi->cols, CV_32FC1 );
CvMat* min_mhi = cvCreateMat( mhi->rows, mhi->cols, CV_32FC1 );
CvMat* max_mhi = cvCreateMat( mhi->rows, mhi->cols, CV_32FC1 );
IplConvKernel* element = cvCreateStructuringElementEx( aperture_size, aperture_size,
aperture_size/2, aperture_size/2, CV_SHAPE_RECT );
int i, j;
double limit = 1e-4*aperture_size*aperture_size;
cvTsPrepareToFilter( mhi, src, anchor );
cvTsCalcSobelKernel2D( 1, 0, aperture_size, 0, kernel );
cvTsConvolve2D( src, dx, kernel, anchor );
cvTsCalcSobelKernel2D( 0, 1, aperture_size, 0, kernel );
cvTsConvolve2D( src, dy, kernel, anchor );
cvReleaseMat( &kernel );
cvTsMinMaxFilter( src, min_mhi, element, CV_TS_MIN );
cvTsMinMaxFilter( src, max_mhi, element, CV_TS_MAX );
cvReleaseStructuringElement( &element );
if( delta1 > delta2 )
{
double t;
CV_SWAP( delta1, delta2, t );
}
for( i = 0; i < mhi->rows; i++ )
{
uchar* mask_row = mask->data.ptr + i*mask->step;
float* orient_row = (float*)(orientation->data.ptr + i*orientation->step);
const float* dx_row = (float*)(dx->data.ptr + i*dx->step);
const float* dy_row = (float*)(dy->data.ptr + i*dy->step);
const float* min_row = (float*)(min_mhi->data.ptr + i*min_mhi->step);
const float* max_row = (float*)(max_mhi->data.ptr + i*max_mhi->step);
for( j = 0; j < mhi->cols; j++ )
{
double delta = max_row[j] - min_row[j];
double _dx = dx_row[j], _dy = dy_row[j];
if( delta1 <= delta && delta <= delta2 &&
(fabs(_dx) > limit || fabs(_dy) > limit) )
{
mask_row[j] = 1;
double angle = atan2( _dy, _dx ) * (180/CV_PI);
if( angle < 0 )
angle += 360.;
orient_row[j] = (float)angle;
}
else
{
mask_row[j] = 0;
orient_row[j] = 0.f;
}
}
}
cvReleaseMat( &dx );
cvReleaseMat( &dy );
cvReleaseMat( &min_mhi );
cvReleaseMat( &max_mhi );
}
static void
icvTsCanny( const CvMat* src, CvMat* dst,
double threshold1, double threshold2,
int aperture_size, int use_true_gradient )
{
int m = aperture_size;
CvMat* _src = cvCreateMat( src->rows + m - 1, src->cols + m - 1, CV_16S );
CvMat* dx = cvCreateMat( src->rows, src->cols, CV_16S );
CvMat* dy = cvCreateMat( src->rows, src->cols, CV_16S );
CvMat* kernel = cvCreateMat( m, m, CV_32F );
CvPoint anchor = {m/2, m/2};
CvMat* mag = cvCreateMat( src->rows, src->cols, CV_32F );
const double tan_pi_8 = tan(CV_PI/8.);
const double tan_3pi_8 = tan(CV_PI*3/8);
float lowThreshold = (float)MIN(threshold1, threshold2);
float highThreshold = (float)MAX(threshold1, threshold2);
int x, y, width = src->cols, height = src->rows;
cvTsConvert( src, dx );
cvTsPrepareToFilter( dx, _src, anchor, CV_TS_BORDER_REPLICATE );
cvTsCalcSobelKernel2D( 1, 0, m, 0, kernel );
cvTsConvolve2D( _src, dx, kernel, anchor );
cvTsCalcSobelKernel2D( 0, 1, m, 0, kernel );
cvTsConvolve2D( _src, dy, kernel, anchor );
/* estimate magnitude and angle */
for( y = 0; y < height; y++ )
{
const short* _dx = (short*)(dx->data.ptr + dx->step*y);
const short* _dy = (short*)(dy->data.ptr + dy->step*y);
float* _mag = (float*)(mag->data.ptr + mag->step*y);
for( x = 0; x < width; x++ )
{
float mval = use_true_gradient ?
(float)sqrt((double)(_dx[x]*_dx[x] + _dy[x]*_dy[x])) :
(float)(abs(_dx[x]) + abs(_dy[x]));
_mag[x] = mval;
}
}
/* nonmaxima suppression */
for( y = 0; y < height; y++ )
{
const short* _dx = (short*)(dx->data.ptr + dx->step*y);
const short* _dy = (short*)(dy->data.ptr + dy->step*y);
float* _mag = (float*)(mag->data.ptr + mag->step*y);
for( x = 0; x < width; x++ )
{
int y1 = 0, y2 = 0, x1 = 0, x2 = 0;
double tg;
float a = _mag[x], b = 0, c = 0;
if( a <= lowThreshold )
continue;
if( _dx[x] )
tg = (double)_dy[x]/_dx[x];
else
tg = DBL_MAX*CV_SIGN(_dy[x]);
if( fabs(tg) < tan_pi_8 )
{
y1 = y2 = y; x1 = x + 1; x2 = x - 1;
}
else if( tan_pi_8 <= tg && tg <= tan_3pi_8 )
{
y1 = y + 1; y2 = y - 1; x1 = x + 1; x2 = x - 1;
}
else if( -tan_3pi_8 <= tg && tg <= -tan_pi_8 )
{
y1 = y - 1; y2 = y + 1; x1 = x + 1; x2 = x - 1;
}
else
{
assert( fabs(tg) > tan_3pi_8 );
x1 = x2 = x; y1 = y + 1; y2 = y - 1;
}
if( (unsigned)y1 < (unsigned)height && (unsigned)x1 < (unsigned)width )
b = (float)fabs((double)mag->data.fl[y1*width+x1]);
if( (unsigned)y2 < (unsigned)height && (unsigned)x2 < (unsigned)width )
c = (float)fabs((double)mag->data.fl[y2*width+x2]);
if( (a > b || (a == b && ((x1 == x+1 && y1 == y) || (x1 == x && y1 == y+1)))) && a > c )
;
else
_mag[x] = -a;
}
}
cvTsZero( dst );
/* hysteresis threshold */
for( y = 0; y < height; y++ )
{
const float* _mag = (float*)(mag->data.ptr + mag->step*y);
uchar* _dst = dst->data.ptr + dst->step*y;
for( x = 0; x < width; x++ )
if( _mag[x] > highThreshold && !_dst[x] )
icvTsCannyFollow( x, y, lowThreshold, mag, dst );
}
cvReleaseMat( &_src );
cvReleaseMat( &dx );
cvReleaseMat( &dy );
cvReleaseMat( &kernel );
cvReleaseMat( &mag );
}
