-- File:	Image_BalancedPixelInterpolation.cdl
-- Created:	Tue Jul 27 18:47:06 1993
-- Author:	Jean Louis FRENKEL
--		<jlf@sparc3>
---Copyright:	 Matra Datavision 1993

class BalancedPixelInterpolation from Image inherits PixelInterpolation from Image

	---Purpose: The class BalancedPixelInterpolation is used to compute a  
	--            SubPixel value on non integer Image coordinate
	--          BalancedPixelInterpolation redefined a new method to compute
	--	      a SubPixel value .
	--	    The value is the proportional to the distance of the 
	--	      four nearest Image Pixel.
	--			A          B
	--			  SubPixel
	--			C          D
	--	    If VA, VB, VC, VD is the value of the four nearest Image 
	--	      Pixel, if ColDelta and RowDelta is the distance from non 
	--	      integer coordinate (FX,FY) to the upper left nearest Image
	--	      Pixel , then :
	--		ColDelta = FX - XA ;
	--		RowDelta = FY - YA ;
	--		CAB = ColDelta*( VB - VA ) + VA 
	--		CCD = ColDelta*( VD - VC ) + VD
	--		V =  RowDelta*( CCD - CAB ) + CAB
	--	      is the Image SubPixel value on non integer 
	--	      coordinate (FX,FY).


uses

    Image 		from Image,
    Pixel       	from Aspect,
    ColorPixel       	from Aspect,
    IndexPixel       	from Aspect,
    DColorImage 	from Image,
    DIndexedImage 	from Image

is

    	Create returns BalancedPixelInterpolation from Image ;
	---Level: Public
    	---Purpose: Create a BalancedPixelInterpolation  object.

	Interpolate( me ; aImage   : Image from Image ;
		          FX,FY      : Real  from Standard ;
			  LowerX,LowerY,UpperX,UpperY : Integer from Standard ;
		          RetPixel : in out Pixel from Aspect ) 
		returns Boolean from Standard is redefined ;
	---Level: Public
    	---Purpose: Redefined the method to compute SubPixel's value 
	--	      on non integer Image coordinate.
	--	    LowerX,LowerY,UpperX,UpperY is the Image Min Max, it's used
	--	      to check if the SubPixel coordinate FX,FY is outside of 
	--	      image.
	--          Return True  if Interpolation Succes.
	--	    Return False if the SubPixel is out from Image.

	Interpolate( me ; aImage   : DColorImage from Image ;
		          FX,FY      : Real  from Standard ;
			  LowerX,LowerY,UpperX,UpperY : Integer from Standard ;
		          RetPixel : in out ColorPixel from Aspect ) 
		returns Boolean from Standard  is redefined;
	---Level: Public
    	---Purpose: Compute SubPixel's value on non integer Image coordinate for
	--	      DColorImage and ColorPixel.
	--	    LowerX,LowerY,UpperX,UpperY is the Image Min Max, it's used
	--	      to check if the SubPixel coordinate FX,FY is outside of 
	--	      image.
	--          Return True  if Interpolation Succes.
	--	    Return False if the SubPixel is out from Image.

	Interpolate( me ; aImage   : DIndexedImage from Image ;
		          FX,FY      : Real  from Standard ;
			  LowerX,LowerY,UpperX,UpperY : Integer from Standard ;
		          RetPixel : in out IndexPixel from Aspect ) 
		returns Boolean from Standard  is redefined;
	---Level: Public
    	---Purpose: Compute SubPixel's value on non integer Image coordinate for
	--	      DIndexedImage and IndexPixel.
	--	    LowerX,LowerY,UpperX,UpperY is the Image Min Max, it's used
	--	      to check if the SubPixel coordinate X,Y is outside of 
	--	      image.
	--          Return True  if Interpolation Succes.
	--	    Return False if the SubPixel is out from Image.

end BalancedPixelInterpolation from Image;