opencv 频率域滤波实例

先上参考链接：http://blog.csdn.net/qq_19764963/article/details/51209970

http://www.cnblogs.com/TonyHome/p/4010116.html

这里给出高斯滤波器的实例，关于傅立叶变换的详细步骤，可以看上一篇博客，这里不做过多介绍了

#include<opencv2/opencv.hpp>
#include<iostream>
using namespace std;
using namespace cv;
int main(int a,char**p)
{
	Mat input=imread(p[1],CV_LOAD_IMAGE_GRAYSCALE);
        //这是在ubuntu上运行的，p[1]为控制台给出的参数，即图片路径
       //如果不知道怎么传入参数，可以直接改为
        //Mat input=imread("image.jpg",CV_LOAD_IMAGE_GRAYSCALE);
        //image.jpg必须放在当前目录下，image.jpg即为输入图片
        imshow("input",input);
	int w=getOptimalDFTSize(input.cols);
	int h=getOptimalDFTSize(input.rows);
	Mat padded;
	copyMakeBorder(input,padded,0,h-input.rows,0,w-input.cols,BORDER_CONSTANT,Scalar::all(0));
	padded.convertTo(padded,CV_32FC1);
	imshow("padded",padded);
	for(int i=0;i<padded.rows;i++)//中心化操作，其余操作和上一篇博客的介绍一样
	{
		float *ptr=padded.ptr<float>(i);
		for(int j=0;j<padded.cols;j++)	ptr[j]*=pow(-1,i+j);
	}
	Mat plane[]={padded,Mat::zeros(padded.size(),CV_32F)};
	Mat complexImg;
	merge(plane,2,complexImg);
	dft(complexImg,complexImg);
//************************gaussian****************************
	Mat gaussianBlur(padded.size(),CV_32FC2);
	Mat gaussianSharpen(padded.size(),CV_32FC2);
	float D0=2*10*10;
	for(int i=0;i<padded.rows;i++)
	{
		float*p=gaussianBlur.ptr<float>(i);
		float*q=gaussianSharpen.ptr<float>(i);
		for(int j=0;j<padded.cols;j++)
		{
			float d=pow(i-padded.rows/2,2)+pow(j-padded.cols/2,2);
			p[2*j]=expf(-d/D0);
			p[2*j+1]=expf(-d/D0);
			
			q[2*j]=1-expf(-d/D0);
			q[2*j+1]=1-expf(-d/D0);
		}
	}
	multiply(complexImg,gaussianBlur,gaussianBlur);//矩阵元素对应相乘法，注意，和矩阵相乘区分
	multiply(complexImg,gaussianSharpen,gaussianSharpen);
//*****************************************************************	
	split(complexImg,plane);
	magnitude(plane[0],plane[1],plane[0]);
	plane[0]+=Scalar::all(1);
	log(plane[0],plane[0]);
	normalize(plane[0],plane[0],1,0,CV_MINMAX);
	imshow("dft",plane[0]);
//******************************************************************
	split(gaussianBlur,plane);
	magnitude(plane[0],plane[1],plane[0]);
	plane[0]+=Scalar::all(1);
	log(plane[0],plane[0]);
	normalize(plane[0],plane[0],1,0,CV_MINMAX);
	imshow("gaussianBlur",plane[0]);
	
	split(gaussianSharpen,plane);
	magnitude(plane[0],plane[1],plane[0]);
	plane[0]+=Scalar::all(1);
	log(plane[0],plane[0]);
	normalize(plane[0],plane[0],1,0,CV_MINMAX);
	imshow("gaussianSharpen",plane[0]);
//******************************************************************
//*************************idft*************************************
	idft(gaussianBlur,gaussianBlur);
	idft(gaussianSharpen,gaussianSharpen);
	split(gaussianBlur,plane);
	magnitude(plane[0],plane[1],plane[0]);
	normalize(plane[0],plane[0],1,0,CV_MINMAX);
	imshow("idft-gaussianBlur",plane[0]);

	split(gaussianSharpen,plane);
	magnitude(plane[0],plane[1],plane[0]);
	normalize(plane[0],plane[0],1,0,CV_MINMAX);
	imshow("idft-gaussianSharpen",plane[0]);
	
	waitKey();
	return 0;
}
		

运行结果如图所示