Emgu 3.0+中图像的离散傅立叶变换

using Emgu.CV;
using Emgu.CV.CvEnum;
using Emgu.CV.Dnn;
using Emgu.CV.Structure;

Mat image = CvInvoke.Imread("path_to_your_image.jpg", ImreadModes.Color);

Mat grayImage = new Mat();
CvInvoke.CvtColor(image, grayImage, ColorConversion.Bgr2Gray);

Mat padded = new Mat();
int m = CvInvoke.GetOptimalDFTSize(grayImage.Rows);
int n = CvInvoke.GetOptimalDFTSize(grayImage.Cols);
CvInvoke.CopyMakeBorder(grayImage, padded, 0, m - grayImage.Rows, 0, n - grayImage.Cols, BorderType.Constant, new MCvScalar(0));

Mat planes[] = { padded, Mat.Zeros(padded.Size, DepthType.Cv32F, 1) };
Mat complexImage = new Mat();
CvInvoke.Merge(planes, complexImage);

CvInvoke.Dft(complexImage, complexImage, DftType.Forward, 0);

// 将结果拆分为实部和虚部
Mat[] planesDFT = new Mat[2];
CvInvoke.Split(complexImage, planesDFT);

// 计算幅度谱
Mat mag = new Mat();
CvInvoke.Magnitude(planesDFT[0], planesDFT[1], mag);

// 归一化以便显示
mag += 1;
CvInvoke.Log(mag, mag);
mag /= mag.Rows;

CvInvoke.NamedWindow("Original Image", NamedWindowType.AutoSize);
CvInvoke.NamedWindow("DFT Result", NamedWindowType.AutoSize);
CvInvoke.Imshow("Original Image", image);
CvInvoke.Imshow("DFT Result", mag);
CvInvoke.WaitKey(0);