pro cnt, overl, WINDOW_SCALE = window_scale, ASPECT = aspect, $
	INTERP = interp,nlevels=nlevels,title=title,subtitle=subtitle,$
	delta=delta

sz = size(overl)			;Size of image

	;set window used by contour
contour,[[0,0],[1,1]],/nodata, xstyle=4, ystyle = 4

px = !x.window * !d.x_vsize	;Get size of window in device units
py = !y.window * !d.y_vsize
swx = px(1)-px(0)		;Size in x in device units
swy = py(1)-py(0)		;Size in Y
six = float(sz(1))		;Image sizes
siy = float(sz(2))
aspi = six / siy		;Image aspect ratio
aspw = swx / swy		;Window aspect ratio
f = aspi / aspw			;Ratio of aspect ratios

if sz(0) eq 2 then begin

  if (!d.flags and 1) ne 0 then begin	;Scalable pixels? -> adjust window size
    if f ge 1.0 then swy = swy / f else swx = swx * f	;retain aspect
  endif else begin	;Not scalable pixels	
    if keyword_set(window_scale) then begin ;Scale window to image?
      swx = six		;Set window size from image
      swy = siy
    endif else begin		;Scale window
      if f ge 1.0 then swy = swy / f else swx = swx * f	;retain aspect
    endelse			;window_scale
  endelse			;scalable pixels

endif


dim=size(overl) & getrange,overl,mn,mx,threshold=.001
center=[dim(1)/2,dim(2)/2]
centerval=overl(center(0),center(1))
if keyword_set(nlevels) then nlev=nlevels else nlev=10
if keyword_set(delta) then delta=delta else delta=(mx-mn)/nlev
if keyword_set(title) then title=title else title=' '
if keyword_set(subtitle) then subtitle=subtitle else subtitle=' ' 

lev=(findgen(nlev)*delta)-nlev/2*delta +(centerval/delta)*delta
;lev=(findgen(nlev)*delta)+mn

contour,overl,/noerase,ystyle=1,xstyle=1,title=title,$ 
subtitle=subtitle,c_labels=lev,levels=lev,$
pos = [px(0),py(0), px(0)+swx,py(0)+swy],/dev

return 
end