com.twelvemonkeys.image
Class DiffusionDither

java.lang.Object
  com.twelvemonkeys.image.DiffusionDither

All Implemented Interfaces:

BufferedImageOp, RasterOp

public class DiffusionDither
extends Object
implements BufferedImageOp, RasterOp

This BufferedImageOp/RasterOp implements basic Floyd-Steinberg error-diffusion algorithm for dithering.

The weights used are 7/16, 3/16, 5/16 and 1/16, distributed like this:

	X	7/16
3/16	5/16	1/16

See Computer Graphics (Foley et al.) for more information.

Version:

$Id: DiffusionDither.java#1 $

Author:

Harald Kuhr, last modified by $Author: haku $

Field Summary

protected IndexColorModel

indexColorModel

Constructor Summary

DiffusionDither()
Creates a DiffusionDither, with no fixed IndexColorModel.

DiffusionDither(IndexColorModel pICM)
Creates a DiffusionDither, using the given IndexColorModel for dithering into.

Method Summary

BufferedImage	createCompatibleDestImage(BufferedImage pSource, ColorModel pDestCM) Creates a compatible BufferedImage to dither into.
WritableRaster	createCompatibleDestRaster(Raster pSrc) Creates a compatible Raster to dither into.
WritableRaster	createCompatibleDestRaster(Raster pSrc, IndexColorModel pIndexColorModel) Creates a compatible Raster to dither into.
BufferedImage	filter(BufferedImage pSource, BufferedImage pDest) Performs a single-input/single-output dither operation, applying basic Floyd-Steinberg error-diffusion to the image.
WritableRaster	filter(Raster pSource, WritableRaster pDest) Performs a single-input/single-output dither operation, applying basic Floyd-Steinberg error-diffusion to the image.
WritableRaster	filter(Raster pSource, WritableRaster pDest, IndexColorModel pColorModel) Performs a single-input/single-output dither operation, applying basic Floyd-Steinberg error-diffusion to the image.
Rectangle2D	getBounds2D(BufferedImage pSrc) Returns the bounding box of the filtered destination image.
Rectangle2D	getBounds2D(Raster pSrc) Returns the bounding box of the filtered destination Raster.
Point2D	getPoint2D(Point2D pSrcPt, Point2D pDstPt) Returns the location of the destination point given a point in the source.
RenderingHints	getRenderingHints() Returns the rendering mHints for this op.
void	setAlternateScans(boolean pUse) Sets the scan mode.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

indexColorModel

protected final IndexColorModel indexColorModel

Constructor Detail

DiffusionDither

public DiffusionDither(IndexColorModel pICM)

Creates a DiffusionDither, using the given IndexColorModel for dithering into.

Parameters:

pICM - an IndexColorModel.

DiffusionDither

public DiffusionDither()

Creates a DiffusionDither, with no fixed IndexColorModel. The color model will be generated for each filtering, unless the destination image already has an IndexColorModel.

Method Detail

setAlternateScans

public void setAlternateScans(boolean pUse)

Sets the scan mode. If the parameter is true, error distribution for every even line will be left-to-right, while odd lines will be right-to-left. The default is true.

Parameters:

pUse - true if scan mode should be alternating left/right

createCompatibleDestImage

public final BufferedImage createCompatibleDestImage(BufferedImage pSource,
                                                     ColorModel pDestCM)

Creates a compatible BufferedImage to dither into. Only IndexColorModel allowed.

Specified by:

createCompatibleDestImage in interface BufferedImageOp

Returns:

a compatible BufferedImage

Throws:

ImageFilterException - if pDestCM is not null or an instance of IndexColorModel.

createCompatibleDestRaster

public final WritableRaster createCompatibleDestRaster(Raster pSrc)

Creates a compatible Raster to dither into. Only IndexColorModel allowed.

Specified by:

createCompatibleDestRaster in interface RasterOp

Parameters:

pSrc - the source raster

Returns:

a WritableRaster

createCompatibleDestRaster

public final WritableRaster createCompatibleDestRaster(Raster pSrc,
                                                       IndexColorModel pIndexColorModel)

Creates a compatible Raster to dither into.

Parameters:

pSrc - the source raster.

pIndexColorModel - the index color model used to create a Raster.

Returns:

a WritableRaster

getBounds2D

public final Rectangle2D getBounds2D(BufferedImage pSrc)

Returns the bounding box of the filtered destination image. Since this is not a geometric operation, the bounding box does not change.

Specified by:

getBounds2D in interface BufferedImageOp

Parameters:

pSrc - the BufferedImage to be filtered

Returns:

the bounds of the filtered definition image.

getBounds2D

public final Rectangle2D getBounds2D(Raster pSrc)

Returns the bounding box of the filtered destination Raster. Since this is not a geometric operation, the bounding box does not change.

Specified by:

getBounds2D in interface RasterOp

Parameters:

pSrc - the Raster to be filtered

Returns:

the bounds of the filtered definition Raster.

getPoint2D

public final Point2D getPoint2D(Point2D pSrcPt,
                                Point2D pDstPt)

Returns the location of the destination point given a point in the source. If dstPt is not null, it will be used to hold the return value. Since this is not a geometric operation, the srcPt will equal the dstPt.

Specified by:

getPoint2D in interface BufferedImageOp

Specified by:

getPoint2D in interface RasterOp

Parameters:

pSrcPt - a Point2D that represents a point in the source image

pDstPt - a Point2Dthat represents the location in the destination

Returns:

the Point2D in the destination that corresponds to the specified point in the source.

getRenderingHints

public final RenderingHints getRenderingHints()

Returns the rendering mHints for this op.

Specified by:

getRenderingHints in interface BufferedImageOp

Specified by:

getRenderingHints in interface RasterOp

Returns:

the RenderingHints object associated with this op.

filter

public final BufferedImage filter(BufferedImage pSource,
                                  BufferedImage pDest)

Performs a single-input/single-output dither operation, applying basic Floyd-Steinberg error-diffusion to the image.

Specified by:

filter in interface BufferedImageOp

Parameters:

pSource - the source image

pDest - the destination image

Returns:

the destination image, or a new image, if pDest was null.

filter

public final WritableRaster filter(Raster pSource,
                                   WritableRaster pDest)

Performs a single-input/single-output dither operation, applying basic Floyd-Steinberg error-diffusion to the image.

Specified by:

filter in interface RasterOp

Parameters:

pSource - the source raster, assumed to be in sRGB

pDest - the destination raster, may be null

Returns:

the destination raster, or a new raster, if pDest was null.

filter

public final WritableRaster filter(Raster pSource,
                                   WritableRaster pDest,
                                   IndexColorModel pColorModel)

Performs a single-input/single-output dither operation, applying basic Floyd-Steinberg error-diffusion to the image.

Parameters:

pSource - the source raster, assumed to be in sRGB

pDest - the destination raster, may be null

pColorModel - the indexed color model to use

Returns:

the destination raster, or a new raster, if pDest was null.