#define EXTRA_NAME "@fouriertransform."
#include "loadbmp.h"
#define Point(x,y) lpPoints[(x)+(y)*nWidth]
void FFT(COMPLEX * TD, COMPLEX * FD, int power)
{
int count;
int i,j,k,bfsize,p;
double angle;
COMPLEX *W,*X1,*X2,*X;
count=1<<power;
W=(COMPLEX *)malloc(sizeof(COMPLEX)*count/2);
X1=(COMPLEX *)malloc(sizeof(COMPLEX)*count);
X2=(COMPLEX *)malloc(sizeof(COMPLEX)*count);
for(i=0;i<count/2;i++)
{
angle=-i*pi*2/count;
W[i].re=cos(angle);
W[i].im=sin(angle);
}
memcpy(X1,TD,sizeof(COMPLEX)*count);
for(k=0;k<power;k++)
{
for(j=0;j<1<<k;j++)
{
bfsize=1<<(power-k);
for(i=0;i<bfsize/2;i++)
{
p=j*bfsize;
X2[i+p]=Add(X1[i+p],X1[i+p+bfsize/2]);
X2[i+p+bfsize/2]=Mul(Sub(X1[i+p],X1[i+p+bfsize/2]),W[i*(1<<k)]);
}
}
X=X1;
X1=X2;
X2=X;
}
for(j=0;j<count;j++)
{
p=0;
for(i=0;i<power;i++)
{
if (j&(1<<i)) p+=1<<(power-i-1);
}
FD[j]=X1[p];
}
free(W);
free(X1);
free(X2);
}
void Fourier()
{
int w=1,h=1,wp=0,hp=0;
while(w*2<=nWidth)
{
w*=2;
wp++;
}
while(h*2<=nHeight)
{
h*=2;
hp++;
}
int x,y;
BYTE *lpPoints=new BYTE[nWidth*nHeight];
GetPoints(lpPoints);
COMPLEX *TD=new COMPLEX[w*h];
COMPLEX *FD=new COMPLEX[w*h];
for(y=0;y<h;y++)
{
for(x=0;x<w;x++)
{
TD[x+w*y].re=Point(x,y);
TD[x+w*y].im=0;
}
}
for(y=0;y<h;y++)
{
FFT(&TD[w*y],&FD[w*y],wp);
}
for(y=0;y<h;y++)
{
for(x=0;x<w;x++)
{
TD[y+h*x]=FD[x+w*y];
}
}
for(x=0;x<w;x++)
{
FFT(&TD[x*h],&FD[x*h],hp);
}
memset(lpPoints,0,nWidth*nHeight);
double m;
for(y=0;y<h;y++)
{
for(x=0;x<w;x++)
{
m=sqrt(FD[x*h+y].re*FD[x*h+y].re+FD[x*h+y].im*FD[x*h+y].im)/100;
if (m>255) m=255;
Point((x<w/2?x+w/2:x-w/2),nHeight-1-(y<h/2?y+h/2:y-h/2))=(BYTE)(m);
}
}
delete TD;
delete FD;
PutPoints(lpPoints);
delete lpPoints;
}
void main(int argc, char *argv[])
{
if(argc==2)
FileName=argv[1];
else
return;
OpenFile();
Fourier();
SaveAs();
}