;
;  CALLING SEQUENCE:  image=it_add(img1,img2)
;
;  PARAMETERS:		img1, img2 are the two image arrays that are to
;			be combined.  The arrays do not have to be the same 
;			size, however, they must already be centered and 
;			scaled.
;
;  NOTES:		This function will operate on any size INTARR, given
;			to it in any order.  Users should 'zero out' any 
;			unwanted portions of the images because it_add uses
;			'where' logic when combining images.  It looks to 
;			see where image one equals zero and places image two
;			there.  If image one doesn't have very many areas 
;			equal to zero, then there isn't much room for image
;			two.  Use it_disk.pro to get rid of any unwanted
;			stuff outside of a given radius.  Use it_center.pro
;			to center an image in an array of any size.
;
;  RETURN TYPE:		INTARR
;
;  CALLS:		NONE
;
;  HISTORY:		Drafted by Tony Darnell, 20-MAR-97
;			4-APR-94:  Added new addition method when composing an
;				   h-alpha limb image with a coronal image.
;
;


FUNCTION it_add,img1,img2,dpm=dpm,subt=subt



  sz1=SIZE(img1)
  sz2=SIZE(img2)
  x1=sz1(1)
  x2=sz2(1)
  y1=sz1(2)
  y2=sz2(2)

  IF (sz1(1) LT sz2(1)) THEN BEGIN
    print,'IT_ADD:  Image 1 is smaller than Image2'
    print,MIN(img1),MAX(img1)
    print,MIN(img2),MAX(img2)
    temp=INTARR(x2,y2)
    mn=MAX(img1(10:40,10:40))
    print,mn

    cx1=(x2/2.0)-(x1/2.0)
    cy1=(y2/2.0)-(y1/2.0)
    cx2=(x2/2.0)+(x1/2.0)
    cy2=(y2/2.0)+(y1/2.0)

    temp(cx1:cx2-1,cy1:cy2-1)=img1
    IF (KEYWORD_SET(dpm) AND NOT KEYWORD_SET(subt)) THEN BEGIN 
       print,'dpm keyword set.'
       ;temp(where(img2 GT 139))=img2(where(img2 GT 139))  
       temp(where(temp LT 10))=img2(where(temp LT 10))  
       ENDIF $
       ELSE  $
    IF (KEYWORD_SET(subt) AND NOT KEYWORD_SET(dpm)) THEN BEGIN
       print,'subt keyword is set'
       temp(where(temp LE mn))=img2(where(temp LE mn))
       ENDIF  $
       ELSE  $
    IF (KEYWORD_SET(dpm) AND KEYWORD_SET(subt)) THEN BEGIN
       print,'both subt and dpm keywords are set.'
       temp(where(temp LE mn))=img2(where(temp LE mn))
       ENDIF  $
       ELSE $
       temp(where(temp LE mn))=img2(where(temp LE mn))
    image=temp
  END

  IF (sz1(1) GT sz2(1)) THEN BEGIN
    print,'IT_ADD:  Image1 is bigger than Image2'
    print,MIN(img1),MAX(img1)
    print,MIN(img2),MAX(img2)
    temp=INTARR(sz1(1),sz1(2))
    mn=img2(10,10)

    cx1=(x1/2.0)-(x2/2.0)
    cy1=(y1/2.0)-(y2/2.0)
    cx2=(x1/2.0)+(x2/2.0)
    cy2=(y1/2.0)+(y2/2.0)

    temp(cx1:cx2-1,cy1:cy2-1)=img2
    IF (KEYWORD_SET(dpm) AND KEYWORD_SET(subt)) THEN BEGIN
       print,'Both subt and dpm keywords are set.'
       temp(where(temp LE mn))=img1(where(temp LE mn)) 
       ENDIF $
       ELSE $
    IF (KEYWORD_SET(dpm) AND NOT KEYWORD_SET(subt)) THEN BEGIN
       print,'dpm keyword set.'
       temp(where(img1 GT 10))=img1(where(img1 GT 10)) 
       ENDIF $
       ELSE $
    IF (KEYWORD_SET(subt) AND NOT KEYWORD_SET(dpm)) THEN BEGIN
       print,'subt keyword is set.'
       temp(where(temp LE mn))=img1(where(temp LE mn)) 
       ENDIF $
       ELSE $
       temp(where(temp LE 128))=img1(where(temp LE 128))
    image=temp
  END

  IF (sz1(1) EQ sz2(1)) THEN BEGIN
    print,'IT_ADD:  Images are same size'
    temp=INTARR(sz1(1),sz1(2))
    temp=img1
    IF (KEYWORD_SET(dpm)) THEN $
       temp(where(img2 GT 129))=img2(where(img2 GT 129))  $
       ELSE  $
       temp(where(img2 LE 128))=img2(where(img2 LE 128))
    image=temp
  END
RETURN,image
END