PW - Power spectrum - Amplitudes of Fourier transform ||

(2/12/18)

PURPOSE

Generates full, unscrambled Fourier moduli from complex Fourier transform for images or volumes. Reads either a real image/volume or its Fourier transform. The resulting data are real and can be displayed as a normal image. Use 'PW L' for better contrast stretching. Parallelized for OMP Jan 2018.   Example.

SEE ALSO

PW L [Power spectrum - Log10 ||]
PW PH [Phase spectrum ||]
FT [Fourier Transform ||]
RO SD [Rotational average - single line output, doc file]

USAGE

.OPERATION: PW

.INPUT FILE: IMG001
[Enter name of the image/volume. Can be a real image/volume or its Fourier transform.]

.OUTPUT FILE: POW001
[Enter the name of the file where the Fourier transform amplitudes will be placed.]

NOTES

  1. Center (DC) of a 2-D power spectrum is placed at (NX/2+1, NY/2+1). Center (DC) of a 3-D power spectrum is placed at (NX/2+1, NY/2+1, NZ/2+1).

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

SUBROUTINES

PW2SR, PW3SR

CALLER

FOUR1 , FOUR1B

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