fft2rm.c

用c语言实现了图像二维快速傅里叶变换

/* fft2rm.c: fast Fourier transform of 2 dimensional complex array,
 direct and inverse,
 thise program is comtributed by Jiang Youg, 2003. 6 */
#define N1 256
#define N2 256
#include "rowco2r.c"
/*void functf( double A[2][N1][N2] );*/
void main( void )
{
unsigned int i,j;
 double A[2][N1][N2];
double t=0,f=0,d=0;

for(i=0;i<N1;i++)
{ 
	for(j=0;j<N2;j++)
{A[0][i][j]=(i+1)*(j+1);
/*printf("%f\n",A[0][i][j]);*/
}
}

printf("The original data, Ak:\n");

for(i=0;i<N1;i++)
{ 
	for(j=0;j<N2;j++)
    f=f+A[0][i][j];
}
f=f/N1/N2+10;
printf("%f\n",f);
for(i=0;i<N1;i++)
{ 
	for(j=0;j<N2;j++)
    if (A[0][i][j]<f) A[0][i][j]=0;
}
 rowcolumnr( A, 1 );
printf("FFT, direct transform ( A -> x ), x:\n");

for(i=0;i<N1;i++)
{ 
	for(j=0;j<N2;j++)
{
	
    
    t=t+A[0][i][j]*A[0][i][j]+A[1][i][j]*A[1][i][j];
	/*printf("%f,%f\n",A[0][i][j],A[1][i][j]);*/
}
}
t=t/N1/N2;
for(i=0;i<N1;i++)
{ 
	for(j=0;j<N2;j++)
    if ((A[0][i][j]*A[0][i][j]+A[1][i][j]*A[1][i][j])>t)
		d=d+(A[0][i][j]*A[0][i][j]+A[1][i][j]*A[1][i][j])/(f*f*N1*N2);
 
}
printf("%f\n",d);


/*******************************************************************/

}