我正在尝试学习傅立叶和逆傅立叶。我得到了正确的傅立叶结果(我想)。然后问题从逆傅立叶开始,结果是黑色,并且充满了白点。 我正在使用Lenna作为照片。
到目前为止,这是我的代码(主要来自opencvjs,我添加了最后一部分(反部分)):
function fourier(src){
// get optimal size of DFT
let optimalRows = cv.getOptimalDFTSize(src.rows);
let optimalCols = cv.getOptimalDFTSize(src.cols);
let s0 = cv.Scalar.all(0);
let padded = new cv.Mat();
cv.copyMakeBorder(src, padded, 0, optimalRows - src.rows, 0,
optimalCols - src.cols, cv.BORDER_CONSTANT, s0);
// use cv.MatVector to distribute space for real part and imaginary part
let plane0 = new cv.Mat();
padded.convertTo(plane0, cv.CV_32F);
let planes = new cv.MatVector();
let complexI = new cv.Mat();
let plane1 = new cv.Mat.zeros(padded.rows, padded.cols, cv.CV_32F);
planes.push_back(plane0);
planes.push_back(plane1);
cv.merge(planes, complexI);
// in-place dft transform
cv.dft(complexI, complexI);
// compute log(1 + sqrt(Re(DFT(img))**2 + Im(DFT(img))**2))
cv.split(complexI, planes);
cv.magnitude(planes.get(0), planes.get(1), planes.get(0));
let mag = planes.get(0);
let m1 = new cv.Mat.ones(mag.rows, mag.cols, mag.type());
cv.add(mag, m1, mag);
cv.log(mag, mag);
// crop the spectrum, if it has an odd number of rows or columns
let rect = new cv.Rect(0, 0, mag.cols & -2, mag.rows & -2);
mag = mag.roi(rect);
// rearrange the quadrants of Fourier image
// so that the origin is at the image center
let cx = mag.cols / 2;
let cy = mag.rows / 2;
let tmp = new cv.Mat();
let rect0 = new cv.Rect(0, 0, cx, cy);
let rect1 = new cv.Rect(cx, 0, cx, cy);
let rect2 = new cv.Rect(0, cy, cx, cy);
let rect3 = new cv.Rect(cx, cy, cx, cy);
let q0 = mag.roi(rect0);
let q1 = mag.roi(rect1);
let q2 = mag.roi(rect2);
let q3 = mag.roi(rect3);
// exchange 1 and 4 quadrants
q0.copyTo(tmp);
q3.copyTo(q0);
tmp.copyTo(q3);
// exchange 2 and 3 quadrants
q1.copyTo(tmp);
q2.copyTo(q1);
tmp.copyTo(q2);
// The pixel value of cv.CV_32S type image ranges from 0 to 1.
cv.normalize(mag, mag, 0, 1, cv.NORM_MINMAX);
cv.imshow('fourierTransform', mag);
//the inverse part
let inverseTransform = new cv.Mat();
cv.dft(mag,inverseTransform,cv.DFT_INVERSE);
let finalImage = new cv.Mat();
inverseTransform.convertTo(finalImage,cv.CV_8U); //converting back to final image ???
cv.imshow('fourierTransform', finalImage);
}
这里有人可以向我解释为什么会这样吗?任何帮助,我们将不胜感激!