Filter the 3D reconstruction

; Filter the 3D reconstruction
;
; SOURCE:  spider/docs/techs/recon/newprogs/filt.spi 
;
; PURPOSE: Filter the 3D reconstruction to the resolution determined 
;          by the Fourier Shell Correlation test. Use a low-pass 
;          Butterworth filter, setting the upper/lower frequency 
;          limits to the cutoff value +/- 0.05.
;
;  I/O PARAMETERS AND FILES ARE SET HERE:
;
; --------------- Input files ---------------------------------------

 [res] = 'resolution'    ; Doc file containing overall resolution data

 [vol] = 'vol01'         ; Initial reconstruction vol. (from ctf.spi)

 ; --------------- Output files  -------------------------------------

 [fvol] = 'volfq01'      ; Filtered volume

 ; -------------- END BATCH HEADER ---------------------------------

 UD 1,[cutoff]           ; Get cutoff freq. value from resolution doc file
   [res]

 [lo] = [cutoff] - 0.05  ; Lower freq. limit
 [hi] = [cutoff] + 0.05  ; Upper freq. limit

 VM
   echo  ' Filtered: [vol] to create: [fvol]  with freq. limits: {%f6.2%[lo]} ... {%f6.2%[hi]}'

 FQ                      ; Filter quick
   [vol]                 ; Input volume                        (input)
   [fvol]                ; Output volume                       (output)
   7                     ; Filter type = Butterworth low-pass
   [lo],[hi]             ; Upper, lower frequency limits

 VM
   echo  ' '; echo  " Use the 'Surface' operation in WEB to view: [fvol] " ; echo  ' '

 EN
 ;