opencv/modules/imgproc/src/gabor.cpp

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2012-02-06 09:09:54 +08:00
/*M///////////////////////////////////////////////////////////////////////////////////////
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#include "precomp.hpp"
/*
Gabor filters and such. To be greatly extended to have full texture analysis.
For the formulas and the explanation of the parameters see:
http://en.wikipedia.org/wiki/Gabor_filter
*/
cv::Mat cv::getGaborKernel( Size ksize, double sigma, double theta,
double lambd, double gamma, double psi, int ktype )
{
double sigma_x = sigma;
double sigma_y = sigma/gamma;
int nstds = 3;
int xmin, xmax, ymin, ymax;
double c = cos(theta), s = sin(theta);
if( ksize.width > 0 )
xmax = ksize.width/2;
else
xmax = (int)std::max(fabs(nstds*sigma_x*c), fabs(nstds*sigma_y*s));
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if( ksize.height > 0 )
ymax = ksize.height/2;
else
ymax = (int)std::max(fabs(nstds*sigma_x*s), fabs(nstds*sigma_y*c));
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xmin = -xmax;
ymin = -ymax;
CV_Assert( ktype == CV_32F || ktype == CV_64F );
Mat kernel(ymax - ymin + 1, xmax - xmin + 1, ktype);
double scale = 1/(2*CV_PI*sigma_x*sigma_y);
double ex = -0.5/(sigma_x*sigma_x);
double ey = -0.5/(sigma_y*sigma_y);
double cscale = CV_PI*2/lambd;
for( int y = ymin; y <= ymax; y++ )
for( int x = xmin; x <= xmax; x++ )
{
double xr = x*c + y*s;
double yr = -x*s + y*c;
double v = scale*exp(ex*xr*xr + ey*yr*yr)*cos(cscale*xr + psi);
if( ktype == CV_32F )
kernel.at<float>(ymax - y, xmax - x) = (float)v;
else
kernel.at<double>(ymax - y, xmax - x) = v;
}
return kernel;
}
/* End of file. */