Calculate Radial Average Spectrum

Use the FFT2RSPC GX to calculate the radially averaged power spectrum of an FFT2 Transform image.

This step (GX) is already integrated into the MAGMAP Filtering option.

FFT2RSPC dialog options

Name of input transform (grid) file

Select the name of the input transform file.

Script Parameter: FFT2.TRN

Name of output spectrum file

Specify the name of the output radially averaged power spectrum file.

Script Parameter: FFT2.SPC

Application Notes

FFT2 data storage in the .TRN file:

NX= original X dimension

NY= original Y dimension

DX= X element separation

DY= Y element separation

WX= 1/(NX*DX), wavenumber increment in X

WY= 1/(NY*DY), wavenumber increment in Y

QX= 1/(2*DX) , Nyquist in X

QY= 1/(2*DY) , Nyquist in Y

0 +WX +QX

r i r i r i

v NY-1 . . . . . . . . . . -WY

e . . . . . . . . . . -WY*2

c . . . . . . . . . .

t . . . . . . . . . .

o . . . . . . . . . .

r . . . . . . . . . .

. . . . . . . . . . -(QY-WY)

^ . . . . . . . . . . QY

| . . . . . . . . . . QY-WY

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

2 . . . . . . . . . . WY*2

1 . . . . . . . . . . WY

0 . . . . . . . . . . 0

0 1 2 (NX+1) -> element

(The X(-)Y(+) portion will be complex conjugate of the X(+)Y(-) portion)

(The X(-)Y(-) portion will be complex conjugate of the X(+)Y(+) portion)