#include <cxcore.h>
#include <cv.h>
#include <highgui.h>
// 以图像中心为原点，调整傅立叶变换图像的四个象限区，即第一和第三象限交换
// 第二和第四象限交换
void cvShiftDFT(CvArr * src_arr, CvArr * dst_arr )
{
CvMat * tmp;
CvMat q1stub, q2stub;
CvMat q3stub, q4stub;
CvMat d1stub, d2stub;
CvMat d3stub, d4stub;
CvMat * q1, * q2, * q3, * q4;
CvMat * d1, * d2, * d3, * d4;
CvSize size = cvGetSize(src_arr);
CvSize dst_size = cvGetSize(dst_arr);
int cx, cy;
if(dst_size.width != size.width ||
dst_size.height != size.height){
cvError( CV_StsUnmatchedSizes, "cvShiftDFT", "Source and Destination arrays must have equal sizes", __FILE__, __LINE__ );
}
if(src_arr==dst_arr){
tmp = cvCreateMat(size.height/2, size.width/2, cvGetElemType(src_arr));
}
cx = size.width/2;
cy = size.height/2; // image center
q1 = cvGetSubRect( src_arr, &q1stub, cvRect(0,0,cx, cy) );
q2 = cvGetSubRect( src_arr, &q2stub, cvRect(cx,0,cx,cy) );
q3 = cvGetSubRect( src_arr, &q3stub, cvRect(cx,cy,cx,cy) );
q4 = cvGetSubRect( src_arr, &q4stub, cvRect(0,cy,cx,cy) );
d1 = cvGetSubRect( src_arr, &d1stub, cvRect(0,0,cx,cy) );
d2 = cvGetSubRect( src_arr, &d2stub, cvRect(cx,0,cx,cy) );
d3 = cvGetSubRect( src_arr, &d3stub, cvRect(cx,cy,cx,cy) );
d4 = cvGetSubRect( src_arr, &d4stub, cvRect(0,cy,cx,cy) );
if(src_arr!=dst_arr){
if( !CV_ARE_TYPES_EQ( q1, d1 )){
cvError( CV_StsUnmatchedFormats, "cvShiftDFT", "Source and Destination arrays must have the same format", __FILE__, __LINE__ );
}
cvCopy(q3, d1, 0);
cvCopy(q4, d2, 0);
cvCopy(q1, d3, 0);
cvCopy(q2, d4, 0);
}
else{
cvCopy(q3, tmp, 0);
cvCopy(q1, q3, 0);
cvCopy(tmp, q1, 0);
cvCopy(q4, tmp, 0);
cvCopy(q2, q4, 0);
cvCopy(tmp, q2, 0);
}
}
int main(int argc, char ** argv)
{
const char* filename = argc >=2 ? argv[1] : "lena.jpg";
IplImage * im;
IplImage * realInput;
IplImage * imaginaryInput;
IplImage * complexInput;
int dft_M, dft_N;
CvMat* dft_A, tmp;
IplImage * image_Re;
IplImage * image_Im;
double m, M;
im = cvLoadImage( filename, CV_LOAD_IMAGE_GRAYSCALE );
if( !im )
return -1;
realInput = cvCreateImage( cvGetSize(im), IPL_DEPTH_64F, 1);
imaginaryInput = cvCreateImage( cvGetSize(im), IPL_DEPTH_64F, 1);
complexInput = cvCreateImage( cvGetSize(im), IPL_DEPTH_64F, 2);
cvScale(im, realInput, 1.0, 0.0);
cvZero(imaginaryInput);
cvMerge(realInput, imaginaryInput, NULL, NULL, complexInput);
dft_M = cvGetOptimalDFTSize( im->height - 1 );
dft_N = cvGetOptimalDFTSize( im->width - 1 );
dft_A = cvCreateMat( dft_M, dft_N, CV_64FC2 );
image_Re = cvCreateImage( cvSize(dft_N, dft_M), IPL_DEPTH_64F, 1);
image_Im = cvCreateImage( cvSize(dft_N, dft_M), IPL_DEPTH_64F, 1);
// copy A to dft_A and pad dft_A with zeros
cvGetSubRect( dft_A, &tmp, cvRect(0,0, im->width, im->height));
cvCopy( complexInput, &tmp, NULL );
cvGetSubRect( dft_A, &tmp, cvRect(im->width,0, dft_A->cols - im->width,
im->height));
//cvZero( &tmp );
// no need to pad bottom part of dft_A with zeros because of
// use nonzero_rows parameter in cvDFT() call below
cvDFT( dft_A, dft_A, CV_DXT_FORWARD, complexInput->height );
cvNamedWindow("win", 0);
cvNamedWindow("magnitude", 0);
cvShowImage("win", im);
// Split Fourier in real and imaginary parts
cvSplit( dft_A, image_Re, image_Im, 0, 0 );
// 计算功率谱 Mag = sqrt(Re^2 + Im^2)
cvPow( image_Re, image_Re, 2.0);
cvPow( image_Im, image_Im, 2.0);
cvAdd( image_Re, image_Im, image_Re, NULL);
cvPow( image_Re, image_Re, 0.5 );
// 计算 log(1 + Mag)
cvAddS( image_Re, cvScalarAll(1.0), image_Re, NULL ); // 1 + Mag
cvLog( image_Re, image_Re ); // log(1 + Mag)
// 重新安排四个象限，使得原点在图像中心
cvShiftDFT( image_Re, image_Re );
// 调整显示象素的区间，保证最大值为白色，最小值为黑色
cvMinMaxLoc(image_Re, &m, &M, NULL, NULL, NULL);
cvScale(image_Re, image_Re, 1.0/(M-m), 1.0*(-m)/(M-m));
cvShowImage("magnitude", image_Re);
cvWaitKey(-1);
return 0;
}
