spot, so the choice of this depends on
                   the origional image.  If the original image is RGB, chances
                   are that 'neg' needs to be selected.
      sqrsize:     This is half the length of the sides of the square 
                   around the brightest spot to be used in the CM calculation
                   and the orientation  calculation.
      alpha:       This is the weighting parameter for the running
                   background.  It must be close to 1 for best result