(* Last edited on 1999-03-11 00:42:05 by stolfi *)

INTERFACE Interval3x3Window;

IMPORT PGMImageFilter;

TYPE
  T = ARRAY [-1..+1] OF ARRAY [-1..+1] OF Interval;
  Interval = PGMImageFilter.Interval;
  LineBuffer = PGMImageFilter.IntervalBuffer;
  INT = INTEGER;
  LONG = LONGREAL;
  NAT = CARDINAL;
  
PROCEDURE Get(
    x, y: INT; 
    READONLY imBuf: LineBuffer;
    NX, NY: NAT; 
    VAR p: T;
    noPixel: Interval := Interval{0.0d0, 1.0d0};
  );
  (* 
    Extracts from "imBuf" the 3x3 sub-array centered on pixel "[x,y]".
    Fills non-existing elements with "noPixel".
  *)

PROCEDURE Normalize(VAR b: T; r: Interval := Interval{0.0d0, 1.0d0});
  (*
    Applies a shift and scale to all pixels in "b" so that
    they span the given range "r".
  *)

END Interval3x3Window.