opencv的频域滤波

#include <iostream>
#include<opencv2/opencv.hpp>
using namespace cv;
using namespace std;

void myMagnitude(Mat & complexImg,Mat & mI)
{
    Mat planes[2];
    split(complexImg,planes);
    magnitude(planes[0],planes[1],mI);
}
void dftshift(Mat& ds)
{
    int cx=ds.cols/2;//图像的中心点x 坐标
    int cy=ds.rows/2;//图像的中心点y 坐标
    Mat q0=ds(Rect(0,0,cx,cy));//左上
    Mat q1=ds(Rect(cx,0,cx,cy));//右上
    Mat q2=ds(Rect(0,cy,cx,cy));//左下
    Mat q3=ds(Rect(cx,cy,cx,cy));//右下
    Mat tmp;
    q0.copyTo(tmp);
    q3.copyTo(q0);
    tmp.copyTo(q3);
    q1.copyTo(tmp);
    q2.copyTo(q1);
    tmp.copyTo(q2);
}
void displayDftSpectrum(Mat&dftDst,String winName,bool inverseSpectrum)
{
    Mat magI;
    myMagnitude(dftDst,magI);
    if(!inverseSpectrum)//如果是正向傅里叶变换谱
    {
        magI+=Scalar::all(1);
        log(magI,magI);
    }
    normalize(magI,magI,0,1,NORM_MINMAX);
    imshow(winName,magI);
}
void makeFilter(Mat&filter,int R,bool isLowPassFilter)
{
    int cx=filter.cols/2,cy=filter.rows/2;
    int R2=R*R;

    for(int i=0;i<filter.rows;i++)
    {
        Vec2d* pf=filter.ptr<Vec2d>(i);
        for(int j=0;j<filter.cols;j++)
        {
            int r2=(j-cx)*(j-cx)+(i-cy)*(i-cy);
            if(r2<R2)
            {
                pf[j][0]=1;
                pf[j][1]=pf[j][0];
            }
        }
    }
    if(!isLowPassFilter)
    {
     filter =Scalar::all(1)-filter;
    }
    Mat displayFilter;
    extractChannel(filter,displayFilter,0);
    imshow("filter image",displayFilter);
}

int main()
{
    ///读入灰度图像
    Mat src=imread("D:\\Qt\\MyImage\\baboon.jpg",0);
    int ny=src.rows,nx=src.cols;
    cv::copyMakeBorder(src,src,0,ny,0,nx,BORDER_CONSTANT);
    imshow("original image",src);
    /***************傅里叶变换*************/
    src.convertTo(src,CV_64FC1);//转成浮点数据类型
    Mat dftDst(src.size(),CV_64FC2);//预设dft的输出结果矩阵
    dft(src,dftDst,DFT_COMPLEX_OUTPUT,0);//离散傅立叶变换
    dftshift(dftDst);//将傅里叶变换的结果，四象限对角互换
    displayDftSpectrum(dftDst,"dftSpectrum display",false);//显示傅里叶频谱图

    /***************频域滤波*************/
    Mat filter(src.size(),CV_64FC2,Scalar::all(0));
    makeFilter(filter,80,false);
    Mat fftTemp=dftDst.mul(filter);//复数频谱图与滤波器相乘，实现频域滤波
    Mat srcFiltered;
    dft(fftTemp,srcFiltered,DFT_INVERSE);//逆傅里叶变换
    //显示经过滤波后的图像
    displayDftSpectrum(srcFiltered,"filtered image",true);//显示逆傅里叶频谱图
    waitKey();
    return 0;
}