;-------------------------------------------------------------
;+
; NAME:
;       BINBOUND
; PURPOSE:
;       For binary image return array with boundary points set to 1.
; CATEGORY:
; CALLING SEQUENCE:
;       b = binbound(bin_image)
; INPUTS:
;       bin_image = byte binary image (only 0 or 1).   in
; KEYWORD PARAMETERS:
; OUTPUTS:
;       b = array with boundary points set to 1.       out
; COMMON BLOCKS:
; NOTES:
;       Notes: The boundary of a binary image is the set of points
;         in the image that are 1 and also touch a 0.
;         A binary image may be made using logical operators.
;         For example, if an image has both positive and negative
;         values the boundary between them may be found as
;         b = binbound(img gt 0). To put this boundary into
;         another image, A, do:
;         w = where(b eq 1) & a(w) = 255.
; MODIFICATION HISTORY:
;       R. Sterner.  24 June, 1987.
;       R. Sterner, 4 Dec, 1989 --- Converted to Sun.
;	R. Sterner, 21 Nov, 1991 --- removed a multiply.
;       Johns Hopkins University Applied Physics Laboratory.
;
; Copyright (C) 1987, Johns Hopkins University/Applied Physics Laboratory
; This software may be used, copied, or redistributed as long as it is not
; sold and this copyright notice is reproduced on each copy made.  This
; routine is provided as is without any express or implied warranties
; whatsoever.  Other limitations apply as described in the file disclaimer.txt.
;-
;-------------------------------------------------------------
 
	FUNCTION BINBOUND, B, help=hlp
 
	if (n_params(0) lt 1) or keyword_set(hlp) then begin
	  print,' For binary image return array with boundary points set to 1.'
	  print,' b = binbound(bin_image)'
	  print,'   bin_image = byte binary image (only 0 or 1).   in'
	  print,'   b = array with boundary points set to 1.       out'
	  print,' Notes: The boundary of a binary image is the set of points'
	  print,'   in the image that are 1 and also touch a 0.'
	  print,'   A binary image may be made using logical operators.'
	  print,'   For example, if an image has both positive and negative'
	  print,'   values the boundary between them may be found as'
	  print,'   b = binbound(img gt 0). To put this boundary into'
	  print,'   another image, A, do:'
	  print,'   w = where(b eq 1) & a(w) = 255.'
	  return, -1
	endif
 
;	RETURN, (SMOOTH(B,3) LT 1)*B
	RETURN, SMOOTH(B,3) NE B	; Gives double thick for float.
 
	END