(* Last edited on 1999-03-11 01:10:21 by stolfi *)

INTERFACE Pixel3x3Window;

IMPORT PGMImageFilter;

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

END Pixel3x3Window.