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-- File: Image_Convertor.cdl
-- Created: Wed Jul 28 16:08:03 1993
-- Author: Jean Louis FRENKEL
-- <jlf@sparc3>
---Copyright: Matra Datavision 1993
class Convertor from Image
---Purpose: This class is used to convert :
-- a PseudoColorImage to a ColorImage
-- a ColorImage to a PseudoColorImage
-- a PseudoColorImage to a PseudoColorImage with a
-- different ColorMap.
--
-- To convert a PseudoColoImage to a ColorImage we use
-- the PseudoColoImage ColorMap to compute the Color of each
-- Image Pixel ( Lookup operation ) , the resulting image
-- look similar as the original image.
--
-- To convert a ColorImage to a PseudoColorImage or
-- a PseudoColorImage to another PseudoColorImage we use
-- Dithering.
--
-- A dither operation is an inverse lookup operation.For
-- example if we want to dither a ColorImage to a
-- PseudoColorImage, for each Pixel in the ColorImage we search
-- in the PseudoColorImage ColorMap the Entry with the nearest
-- Color, then we write the ColorMap Entry Index in to the
-- PseudoColorImage. The result is a PseudoColorImage that when
-- it is displayed using its own ColorMap it will look as much
-- like the original ColorImage as possible.
--
-- This class provides 2 Dithering method.
--
-- DM_NearestColor : this dithering method is the simplest
-- one ,it just finds the nearest entry in the ColorMap.
-- This algorithm provide no provision for eliminating unwanted
-- contours in the dithered image.This algorithm is much
-- faster on ColorRamp and ColorCube than on Generic
-- ColorMap.Indeed on ColorRamp and ColorCube ColorMap the
-- ColorMap Entry Index can be computed by using the ColorMap
-- BasePixel and ColorDimension.
--
-- DM_ErrorDiffusion: In this method the difference ( error )
-- between the original and the dithered image is distribued
-- to the oginal image pixels immediatly to the right of and
-- below the last pixel processed. The ErrorDiffusion method
-- uses a "floyd-steinberg" error-distribution kernel.This
-- algorithm is fairly time-consuming, but can greatly reduce
-- contouring in the dithered image.
--
uses
ColorMap from Aspect,
GenericColorMap from Aspect,
ColorCubeColorMap from Aspect,
ColorRampColorMap from Aspect,
PseudoColorImage from Image,
ColorImage from Image,
DitheringMethod from Image
is
Create returns Convertor from Image;
---Level: Public
---Purpose: Create a Convertor object with the default DitheringMethod
-- ( DM_NearestColor ).
SetDitheringMethod( me : in out ;
aMethod : in DitheringMethod from Image );
---Level: Public
---Purpose: Set DitheringMethod.
Convert (me : in ;aColorImage: ColorImage from Image;
aColorMap : ColorMap from Aspect)
returns mutable PseudoColorImage from Image;
---Level: Public
---Purpose: Dither a ColorImage into a PseudoColorImage using the
-- ColorMap parameter.
Convert (me : in ; aPseudoColorImage: PseudoColorImage from Image;
aColorMap : ColorMap from Aspect)
returns mutable PseudoColorImage from Image;
---Level: Public
---Purpose: Dither a PseudoColorImage into a PseudoColorImage using the
-- ColorMap parameter.
Convert (me : in; aPseudoColorImage: PseudoColorImage from Image)
returns mutable ColorImage from Image;
---Level: Public
---Purpose: Lookup a PseudoColorImage into a ColorImage using the
-- PseudoColorImage ColorMap.
-- ******************* Private Method *******************
NearestDithering(me : in;
aColorImage: ColorImage from Image ;
aColorMap : ColorMap from Aspect)
returns mutable PseudoColorImage from Image is private ;
NearestDithering(me : in;
aPseudoColorImage : PseudoColorImage from Image ;
aColorMap : ColorMap from Aspect)
returns mutable PseudoColorImage from Image is private ;
ErrorDiffusionDithering(me : in;
aColorImage : ColorImage from Image ;
aColorMap : ColorMap from Aspect)
returns mutable PseudoColorImage from Image is private ;
ErrorDiffusionDithering(me : in;
aPseudoColorImage : PseudoColorImage from Image ;
aColorMap : ColorMap from Aspect)
returns mutable PseudoColorImage from Image is private ;
fields
myDitheringMethod : DitheringMethod from Image ;
end Convertor;
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