SPECTRUM

        [GREG3\]SPECTRUM I [J [K]]
            or
        [GREG3\]SPECTRUM OutSpec InCube [Mask] [/CORNER Imin Imax Jmin Jmax]
      [/PLANE First Last]  /MEAN  or  /SUM

    SPECTRUM I [J [K]]
    Extract a spectrum from an image according to the following numbering:
        Spectrum (l) = Image (l,i,j,k)
    for a 4-dimensional image. The spectrum is loaded into the  X,Y  buffers
    of GreG. It can be processed later by the standard commands LIMITS, CON-
    NECT, CURVE and so on.

    The alternate syntax, used if any option is  present,  computes  in  the
    output variable OutSpec a mean or integrated spectrum over the specified
    region of the input Image variable InCube, using the current Greg  poly-
    gon and the specified Mask if any.