; ----------------------------------------------------------------------
;  Create a sigma image for a subsection of an image.
;  Set siglim high (99999.) for first pass, then low (5.) for second pass.
;
;>  valimg gets set with | image - median | (aka residual)
;>  sigimg get set with residual / error (aka scaled deviation)

pro nsxng_sigma_subsection, nc, nr, image, sigimg, valimg, c1, c2, r1, r2, iipix, jjpix, siglim

  mp = (1+c2-c1) * (1+r2-r1)
  arr = fltarr(mp)

; Median and RMS from median.
;> Not sure why this calls ((ii ne iipix)&&(jj ne jjpix)) --
;> this cuts out the center row and center column
;> rather than just the center pixel
  narr=0
  for ii=c1,c2 do begin
     for jj=r1,r2 do begin
        if ((ii ne iipix)&&(jj ne jjpix)) then begin
           pixno = ii + (jj * long(nc))
           if ( (*sigimg)[pixno] lt siglim) then begin
              arr[narr] = (*image)[pixno]
              ++narr
           endif
        endif
     endfor
  endfor
  median = cfind_median(narr,arr)  ;
  rms=0.                          
  for kk=0L,narr-1 do begin
     rms = rms + ((arr[kk] - median) * (arr[kk] - median))
  endfor
  rms = sqrt(( rms / double(narr) )) ;

; Load sigmas image. */
  pixno = iipix + (jjpix * long(nc))

  (*valimg)[pixno] = (*image)[pixno] - median
  (*sigimg)[pixno] = ABS(( (*valimg)[pixno])) / rms

end