INTERFACE CsiFeatures2D;
(*
  A feature mapper tha computes the "csi" invariants, 
  computed from the pixel and its 8 neighbors:

  |    f
  |    fx^2 + fy^2
  |    fxx + fyy
  |    fxx fyy - fxy^2
  |    fx^2 fxx + 2 fx fy fxy + fy^2 fyy

  Each image layer generates 5 consecutive features. *)

IMPORT FeatureMapper2D AS Mapper;
FROM Mapper IMPORT NAT;

TYPE
  T <: Public;
  Public = Mapper.T OBJECT METHODS
      init(NL: NAT): T; (* Initializes the mapper for "NL" layers. *)
    END;

END CsiFeatures2D.