.OUTPUT FILE: FIC001
[Enter name of output file containing filtered real picture.]
1: low-pass, 2: high-pass, 3: Gauss low-pass, 4: Gauss high-pass 5: Fermi low-pass, 6: Fermi high-pass, 7: Buter low-pass, 8: Buter high-pass
.Filter type (1-8): 7
[Enter filter option code.]
Option "1" - Low-pass truncation. Filter is "top-hat" function that truncates Fourier transform at spatial frequency RAD.
Option "2" - High-pass truncation. Filter is inverse "top-hat" function that passes Fourier transform beyond spatial frequency radius RAD.
Option "3" - Gaussian low-pass. Filter is Gaussian function EXP(-f**2/(2.*RAD**2)), where F is the frequency.
Option "4" - Gaussian high-pass. Filter is complement of Gaussian function: 1.0-EXP(-F**2/(2.*RAD**2)).
Option "5" - Fermi low-pass. Filter is 1/(1+EXP[(F-RAD)/T]) which negotiates between "top-hat" and Gaussian characteristics, depending on the value of T (see below).
Option "6" - Fermi high-pass. As low-pass, but T is replaced by -T.
Option "7" - Butterworth low-pass. Filter is 1/(SQRT(1+F/RAD)**(2*ORDER)) In the actual implementation of the filter the parameters, RAD and ORDER are calculated from the pass-band frequency and cut-off frequency specified by the user. See NOTE 5 below.
Option "8" - Butterworth high-pass. Filter is 1-(1/(SQRT(1+F/RAD)**(2*ORDER)))]
NOTES