PW 2 - Power spectrum

PURPOSE

Generates full, unscrambled Fourier squared moduli from complex Fourier transform for 2-D or 3-D pictures. The input 2D image can be real if it fits into the memory. Operations supports multiple radix FFT, thus the input image does not have to have power-of-two dimensions (see 'FT'). The resulting data are real and can be displayed like a normal image.

SEE ALSO

PW	[Amplitudes of Fourier transform]
PW L	[Power spectrum - Log10]
FT	[Fourier Transform ||]

USAGE

.OPERATION: PW 2

.INPUT FILE: FOU001
[Enter the file name of the Fourier transform.]

.OUTPUT FILE: POW001
[Enter the name of the file where the power spectrum is to be kept.]

NOTES

1. The center of 2-D power spectrum is placed in (NSAM/2+1,NROW/2+1); for 3-D case in (NSAM/2+1,NROW/2+1,NSLICE/2+1).

2. The term |F(0)| is replaced by term |F(1)| to facilitate visualization.

3. Memory requirements:

    
             input image                memory in words 
                2D real                   (NSAM+2)*NROW 
                2D complex                (NSAM+2)*NROW 
                3D real                   (NSAM+2)*NROW*NSLICE 
             

SUBROUTINES

PW2SDR, PW2SR, PW3SDR, PW3SR

CALLER

FOUR1 , FOUR1B