subroutine smei_orb_diff(nx, ny, i_min, i_orbit, i_diff, orb_pattern, dev_cut, icount)

	    integer	nx
	    integer	ny
	    integer	i_min
	    integer	i_orbit
	    integer	i_diff
	    real	orb_pattern(nx,ny,3)
	    integer	icount

	real		z(-1:1,-1:1)

	locFRM(i,j) = i+(j-1)*nx		! Translates 2D array indices (i,j) into linear index

	bad = BadR4()

	! Zero the difference pattern everywhere

	call ArrR4Zero(nx*ny, orb_pattern(1,1,i_diff))

	icount = 0

	! Here use the plane program to find deviations of a pixel from its
	! immediate neighbors, call that the "pattern"

	do j=2,ny-1				! Stay away from edges
	    do i=2,nx-1

		! Pick up difference between current orbital pattern and the first one.

		do jj=-1,1
		    do ii=-1,1

			ip = locFRM(i+ii,j+jj)

			z0 = orb_pattern(i+ii,j+jj,i_orbit)	! Minimum for this orbit
			z1 = orb_pattern(i+ii,j+jj,i_min  )	! Minimum for mimimum orbit

			if (z0 .ne. bad .and. z1. ne. bad) then
			    z(ii,jj) = z0-z1
			else
			    z(ii,jj) = bad
			end if

		    end do
		end do

		call ArrR4GetMinMax(9,z,zmin,zmax)
		z0 = z(0,0)

		! Continue only if none of the 9 pixels are bad, and the center pixels is the
		! smallest or largest value (with no other pixel equal to the center value).

		if (iArrR4ValuePresent(9,z,bad) .eq. 0 .and.
     &			iArrR4ValuePresent(9,z,z0 ) .eq. 1 .and. (z0 .eq. zmin .or. z0 .eq. zmax)) then

		    call smei_FitPlane(z,z,z0,a,b,sumzq)

		    ! Try to improve a pattern value when just one screwy neighbor is present

		    z0 = z(0,0)	
		    z1 = max(dev_cut,0.1*abs(z0))

		    ibad = 0
		    zbad = 0
		    do ii=-1,1
			do jj=-1,1
			    val = z(ii,jj)
			    if (abs(val) .gt. z1) then	! Shouldn't we exclude the center pixel here???
				ibad = ibad+1
				zbad = val
			    end if
			end do
		    end do

		   if (ibad .le. 1) then
			z0 = z0-zbad/8.0
			orb_pattern(i,j,i_diff) = z0
			if (abs(z0) .gt. 10.0) icount = icount+1
		   end if

		end if

	    end do
	end do

	return
	end