//-------------------------------------------------------------------------
void InitializeArrays()
//-------------------------------------------------------------------------
{
int i, j, pos;
double Normalize = 0.0;
Window = 2*halfWindow + 1; Window2 = Window*Window;
H = new double[3*NxNy];
kernelGxx = new double[Window2];
kernelGyy = new double[Window2];
kernelGxy = new double[Window2];
for(i = -halfWindow; i <= halfWindow; i++){
for(j = -halfWindow; j <= halfWindow; j++){
pos = i+halfWindow + (j+halfWindow)*Window;
kernelGxx[pos] = Gxx((double)i*hx,(double)j*hy);
kernelGyy[pos] = Gyy((double)i*hx,(double)j*hy);
kernelGxy[pos] = Gxy((double)i*hx,(double)j*hy);
Normalize += kernelGxx[pos];
}
}
//---------------------------------------------------------------------
if(Normalize != 0){
for(i = -halfWindow; i <= halfWindow; i++){
for(j = -halfWindow; j <= halfWindow; j++){
pos = i+halfWindow + (j+halfWindow)*Window;
kernelGxx[pos] -= (Normalize/(double)Window2);
kernelGyy[pos] -= (Normalize/(double)Window2);
}
}
}
};
/*static*/ void ImageFilter::computeDerivativesOfImage(const cv::Mat& img, const std::size_t apertureSize, const double sigma, cv::Mat& Fx, cv::Mat& Fy, cv::Mat& Fxx, cv::Mat& Fyy, cv::Mat& Fxy)
{
// Compute derivatives wrt xy-coordinate system.
cv::Mat Gx(apertureSize, apertureSize, CV_64F), Gy(apertureSize, apertureSize, CV_64F);
cv::Mat Gxx(apertureSize, apertureSize, CV_64F), Gyy(apertureSize, apertureSize, CV_64F), Gxy(apertureSize, apertureSize, CV_64F);
DerivativesOfGaussian::getFirstOrderDerivatives(apertureSize, sigma, Gx, Gy);
DerivativesOfGaussian::getSecondOrderDerivatives(apertureSize, sigma, Gxx, Gyy, Gxy);
// Make sure that the sum (or average) of all elements of the kernel has to be zero (similar to the Laplace kernel) so that the convolution result of a homogeneous regions is always zero.
// REF [site] >> http://fourier.eng.hmc.edu/e161/lectures/gradient/node8.html
const double kernelArea = (double)apertureSize * (double)apertureSize;
Gx -= cv::sum(Gx) / kernelArea;
Gy -= cv::sum(Gy) / kernelArea;
Gxx -= cv::sum(Gxx) / kernelArea;
Gyy -= cv::sum(Gyy) / kernelArea;
Gxy -= cv::sum(Gxy) / kernelArea;
// Compute Fx, Fy, Fxx, Fyy, Fxy.
cv::filter2D(img, Fx, CV_64F, Gx, cv::Point(-1, -1), 0, cv::BORDER_DEFAULT);
cv::filter2D(img, Fy, CV_64F, Gy, cv::Point(-1, -1), 0, cv::BORDER_DEFAULT);
cv::filter2D(img, Fxx, CV_64F, Gxx, cv::Point(-1, -1), 0, cv::BORDER_DEFAULT);
cv::filter2D(img, Fyy, CV_64F, Gyy, cv::Point(-1, -1), 0, cv::BORDER_DEFAULT);
cv::filter2D(img, Fxy, CV_64F, Gxy, cv::Point(-1, -1), 0, cv::BORDER_DEFAULT);
}
