; diffmap 
; Computes difference bewteen two volumes: in this case,
; a reconstruction minus the reference volume.
;
; NB : use the raw unfiltered volumes
;
; x44 = 1 : Use the same mask for both reference and test volume
; (better for identifying a ligand)
; x44 = 2 : create masks for both volume (better for identifying
; conformational changes)

x44 = 1		; use same mask

;
;  filter parameters for volumes
x81=0.15
x82=0.25

; final filtration for the difference map
;x83=0.12
;x84=0.25

;..............................
; the reference volume
CP 
con001
_9

FQ
_9
_1
7            ; Butterworth filter
x81,x82      ; pass-band and stop-band frequencies

FS x21,x22   ; max & min 
_1

x52=(x22-x21)/2   ; The threshold is a value
x52=x52+x21       ; halfway between min & max

TH M       ; Threshold & create Mask
_1
_5         ; output mask
b          ; If (pixel > threshold) Mask = 1; else Mask = 0
x52        ; threshold

FS M,x21,x22,x23,x24  ; Find Statistics within a mask (max, min, avg, stddev)
_1         ; image
_5         ; mask

AR
_1
_7
((p1-x23)/x24)

; 2nd volume: the reference is subtracted from this volume
CP
vol006
_9

FQ
_9
_2
7
x81,x82

IF (x44.EQ.1) GOTO LB1
; this part creates a mask for the 2nd volume

FS x21,x22   ; max & min 
_2

x52=(x22-x21)/2   ; The threshold is a value
x52=x52+x21       ; halfway between min & max

TH M       ; Threshold & create Mask
_2
_5         ; output mask
b          ; If (pixel > threshold) Mask = 1; else Mask = 0
x52        ; threshold


LB1

FS M,x21,x22,x23,x24
_2         ; image
_5         ; mask (either from reference or created for 2nd vol)

AR
_2
_6
((p1-x23)/x24)

SU
_6		; 2nd volume
_7		; reference
_5		; result
*

FQ 
_5
_8
7
x81,x82

FS   ; statistics before filtering
_5

FS   ; statistics after filtering
_8

CP
_5
dif201

CP
_8
diff201

EN D