fft2m.c

用c语言实现了图像二维快速傅里叶变换

/* fft2m.c: fast Fourier transform of 2 dimensional complex array, 
 direct and inverse, thise program is comtributed by Jiang Youg, 2003. 6 */
#define N1 512
#define N2 512
#include "rowco2.c"
void functf( double A[2][N1][N2] );
/*extern void rowcolumn( double A[2][N1][N2], int ifft );*/
void main( void )
{
unsigned int i,j;
static double A[2][N1][N2];
FILE *fp;
fp=fopen("fft2m.d","w");
system("cls");
functf( A );
printf("The original data, Ak:\n");
fprintf(fp,"The original data, Ak:\n");
for(i=0;i<N1;i++)
{ for(j=0;j<N2;j++)
    fprintf(fp,"%4u,%4u:  %15.9f, %16.8e",i,j,A[0][i][j],A[1][i][j]);
  fprintf(fp,"\n"); }
rowcolumn( A, 1 );
printf("FFT, direct transform ( A -> x ), x:\n");
fprintf(fp,"FFT, direct transform ( A -> x ), x:\n");
for(i=0;i<N1;i++)
{ for(j=0;j<N2;j++)
    fprintf(fp,"%4u,%4u:  %15.9f, %16.8e",i,j,A[0][i][j],A[1][i][j]);
  fprintf(fp,"\n"); }
rowcolumn( A, -1 );
printf("IFFT, inverse transform ( x -> A ), A:\n");
fprintf(fp,"IFFT, inverse transform ( x -> A ), A:\n");
for(i=0;i<N1;i++)
{ for(j=0;j<N2;j++) 
	fprintf(fp,"%4u,%4u:  %15.9f, %16.8e",i,j,A[0][i][j],A[1][i][j]);
  fprintf(fp,"\n"); }
fclose(fp);
printf("OK!\n");
}
/*******************************************************************/
void functf( double A[2][N1][N2] )
{
unsigned int i,j;
double tti,ttj,dti,dtj,pi,A0i,A1i,A0j,A1j;
dti=0.1;  dtj=dti; pi=4.0*atan(1.0);
A0i=exp(-N1*dti);  A0j=exp(-N2*dtj);
for(i=0;i<N1;i++)
  { tti=(double)i*dti; A1i=exp(-tti);
    for(j=0;j<N2;j++)
      { ttj=(double)j*dtj; A1j=exp(-ttj);
        A[0][i][j]=(A1i+A0i/A1i)*dti*(A1j+A0j/A1j)*dtj;
        A[1][i][j]=0.0; } }
}