Hi, i try to apply the inverse of fourier Trasform to a Image Sperctrum but it does not work, i end up with a black image.
Mat Lena;
images[0].copyTo(Lena);
Mat padded; //expand input image to optimal size
int m = getOptimalDFTSize( Lena.rows );
int n = getOptimalDFTSize( Lena.cols ); // on the border add zero values
copyMakeBorder(Lena, padded, 0, m - Lena.rows, 0, n - Lena.cols, BORDER_CONSTANT, Scalar::all(0));
Mat planes[] = {Mat_<float>(padded), Mat::zeros(padded.size(), CV_32F)};
Mat complexI;
merge(planes, 2, complexI); // Add to the expanded another plane with zeros
dft(complexI, complexI); // this way the result may fit in the source matrix
Mat_<float> magI;
split(complexI, planes); // planes[0] = Re(DFT(I), planes[1] = Im(DFT(I))
magnitude(planes[0], planes[1], planes[0]);// planes[0] = magnitude
magI=planes[0];
//shifting
dftshift(magI);
magI(cv::Rect(magI.cols/2 - 25, magI.rows/2 -25, 50, 50)) = 250.0f;
dftshift(magI);
Mat_<float> filtered;
//from polar to car
//phase(planes[1], planes[0], planes[1], false);
polarToCart(magI,planes[1],planes[0],planes[1],false);
//merge
Mat_<Vec2f> complexI_2;
merge(planes, 2, complexI_2);
dft(complexI_2, filtered, DFT_INVERSE + DFT_SCALE + DFT_REAL_OUTPUT, 0);
normalize(filtered, filtered, 0, 1, CV_MINMAX);
namedWindow("Filtered Im", CV_WINDOW_AUTOSIZE );
imshow("Filtered Im", filtered );
namedWindow("ImageHisto", CV_WINDOW_AUTOSIZE );
imshow("ImageHisto", histo(Lena) );
namedWindow("FilteredImage Histo", CV_WINDOW_AUTOSIZE );
imshow("FilteredImage Histo", histo(filtered) );
}
Everything is working until i modify the magnitude. I get the modified spectrum (magI) end then i am suppose to compute the inverse Trasform. I think the problem could be in PolarToCar because it takes as parameter the magnitude and the phase, but i am not sure i actually have the phase, i think i have the imaginary part of the spectrum stored in planes[1]. thanks
