javax.media.jai
Class KernelJAI

java.lang.Object
  |
  +--javax.media.jai.KernelJAI

All Implemented Interfaces:

Serializable

public class KernelJAI

extends Object

implements Serializable

A kernel representing a matrix with a key position, used by operators such as Convolve .

A KernelJAI is characterized by its width, height, and origin, or key element. The key element is the element which is placed over the current source pixel to perform convolution or error diffusion.

A kernel K is separable it the outer product of two one-dimensional vectors. It can speed up computation. One can construct a kernel from two one-dimensional vectors. <>The symmetry can be useful (such as computation speedup). Currently the protected instance variables isHorizonallySymmetric and isVerticallySymmetric are set to false.

See Also:

ConvolveDescriptor, OrderedDitherDescriptor, ErrorDiffusionDescriptor, Serialized Form

Field Summary

protected float[]	data The kernel data in row-major format.
protected float[]	dataH The horizontal data for a separable kernel
protected float[]	dataV The vertical data for a separable kernel
static KernelJAI[]	DITHER_MASK_441 4x4x1 mask useful for dithering 8-bit grayscale images to 1-bit images.
static KernelJAI[]	DITHER_MASK_443 4x4x3 mask useful for dithering 24-bit color images to 8-bit pseudocolor images.
static KernelJAI	ERROR_FILTER_FLOYD_STEINBERG Floyd and Steinberg error filter (1975).
static KernelJAI	ERROR_FILTER_JARVIS Jarvis, Judice, and Ninke error filter (1976).
static KernelJAI	ERROR_FILTER_STUCKI Stucki error filter (1981).
static KernelJAI	GRADIENT_MASK_SOBEL_HORIZONTAL Gradient Mask for SOBEL_HORIZONTAL
static KernelJAI	GRADIENT_MASK_SOBEL_VERTICAL Gradient Mask for SOBEL_VERTICAL
protected int	height The height of the kernel.
protected boolean	isHorizontallySymmetric True if the kernel has horizontal (Y axis) symmetry.
protected boolean	isSeparable True if the kernel is separable.
protected boolean	isVerticallySymmetric True if the kernel has vertical (X axis) symmetry.
protected KernelJAI	rotatedKernel Variable to cache a copy of the rotated kernel
protected int	width The width of the kernel.
protected int	xOrigin The X coordinate of the key element.
protected int	yOrigin The Y coordinate of the key element.

Constructor Summary

KernelJAI(int width, int height, float[] data)
Constructs a kernel with the given parameters.

KernelJAI(int width, int height, int xOrigin, int yOrigin, float[] data)
Constructs a KernelJAI with the given parameters.

KernelJAI(int width, int height, int xOrigin, int yOrigin, float[] dataH, float[] dataV)
Constructs a separable KernelJAI from two float arrays.

KernelJAI(Kernel k)
Constructs a KernelJAI from a java.awt.image.Kernel object.

Method Summary

int	getBottomPadding() Returns the number of pixels required below the key element.
float	getElement(int xIndex, int yIndex) Returns a given element of the kernel.
int	getHeight() Returns the height of the kernel.
float[]	getHorizontalKernelData() Returns the horizontal portion of the kernel if the kernel is separable, or null otherwise.
float[]	getKernelData() Returns a copy of the kernel data in row-major format.
int	getLeftPadding() Returns the number of pixels required to the left of the key element.
int	getRightPadding() Returns the number of pixels required to the right of the key element.
KernelJAI	getRotatedKernel() Returns a 180 degree rotated version of the kernel.
int	getTopPadding() Returns the number of pixels required above the key element.
float[]	getVerticalKernelData() Returns the vertical portion of the kernel if the kernel is separable, or null otherwise.
int	getWidth() Returns the width of the kernel.
int	getXOrigin() Returns the X coordinate of the key kernel element.
int	getYOrigin() Returns the Y coordinate of the key kernel element.
boolean	isHorizontallySymmetric() Returns true if the kernel has horizontal (Y axis) symmetry.
boolean	isSeparable() Returns true if the kernel is separable.
boolean	isVerticallySymmetric() Returns true if the kernel has vertical (X axis) symmetry.

Methods inherited from class java.lang.Object

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

Field Detail

ERROR_FILTER_FLOYD_STEINBERG

public static final KernelJAI ERROR_FILTER_FLOYD_STEINBERG

Floyd and Steinberg error filter (1975).

 (1/16 x)  [   * 7 ]
           [ 3 5 1 ]
 

ERROR_FILTER_JARVIS

public static final KernelJAI ERROR_FILTER_JARVIS

Jarvis, Judice, and Ninke error filter (1976).

           [     * 7 5 ]
 (1/48 x)  [ 3 5 7 5 3 ]
           [ 1 3 5 3 1 ]
 

ERROR_FILTER_STUCKI

public static final KernelJAI ERROR_FILTER_STUCKI

Stucki error filter (1981).

           [     * 7 5 ]
 (1/42 x)  [ 2 4 8 4 2 ]
           [ 1 2 4 2 1 ]
 

DITHER_MASK_441

public static final KernelJAI[] DITHER_MASK_441

4x4x1 mask useful for dithering 8-bit grayscale images to 1-bit images.

DITHER_MASK_443

public static final KernelJAI[] DITHER_MASK_443

4x4x3 mask useful for dithering 24-bit color images to 8-bit pseudocolor images.

GRADIENT_MASK_SOBEL_HORIZONTAL

public static final KernelJAI GRADIENT_MASK_SOBEL_HORIZONTAL

Gradient Mask for SOBEL_HORIZONTAL

GRADIENT_MASK_SOBEL_VERTICAL

public static final KernelJAI GRADIENT_MASK_SOBEL_VERTICAL

Gradient Mask for SOBEL_VERTICAL

width

protected int width

The width of the kernel.

height

protected int height

The height of the kernel.

xOrigin

protected int xOrigin

The X coordinate of the key element.

yOrigin

protected int yOrigin

The Y coordinate of the key element.

data

protected float[] data

The kernel data in row-major format.

dataH

protected float[] dataH

The horizontal data for a separable kernel

dataV

protected float[] dataV

The vertical data for a separable kernel

isSeparable

protected boolean isSeparable

True if the kernel is separable.

isHorizontallySymmetric

protected boolean isHorizontallySymmetric

True if the kernel has horizontal (Y axis) symmetry.

isVerticallySymmetric

protected boolean isVerticallySymmetric

True if the kernel has vertical (X axis) symmetry.

rotatedKernel

protected KernelJAI rotatedKernel

Variable to cache a copy of the rotated kernel

Constructor Detail

KernelJAI

public KernelJAI(int width,
                 int height,
                 int xOrigin,
                 int yOrigin,
                 float[] data)

Constructs a KernelJAI with the given parameters. The data array is copied.

Parameters:

width - the width of the kernel.

height - the height of the kernel.

xOrigin - the X coordinate of the key kernel element.

yOrigin - the Y coordinate of the key kernel element.

data - the float data in row-major format.

Throws:

IllegalArgumentException - if data is null.

IllegalArgumentException - if width is not a positive number.

IllegalArgumentException - if height is not a positive number.

IllegalArgumentException - if kernel data array does not have width * height number of elements.

KernelJAI

public KernelJAI(int width,
                 int height,
                 int xOrigin,
                 int yOrigin,
                 float[] dataH,
                 float[] dataV)

Constructs a separable KernelJAI from two float arrays. The data arrays are copied. A Separable kernel K = dataH * dataV^T, the outer product of two one dimensional vectors dataH and dataV. It can often speed up compution.

Parameters:

width - the width of the kernel.

height - the height of the kernel.

xOrigin - the X coordinate of the key kernel element.

yOrigin - the Y coordinate of the key kernel element.

dataH - the float data for the horizontal direction.

dataV - the float data for the vertical direction.

Throws:

IllegalArgumentException - if dataH is null.

IllegalArgumentException - if dataV is null.

IllegalArgumentException - if width is not a positive number.

IllegalArgumentException - if height is not a positive number.

IllegalArgumentException - if dataH does not have width elements.

IllegalArgumentException - if dataV does not have height elements.

KernelJAI

public KernelJAI(int width,
                 int height,
                 float[] data)

Constructs a kernel with the given parameters. The data array is copied. The key element is set to (trunc(width/2), trunc(height/2)).

Parameters:

width - the width of the kernel.

height - the height of the kernel.

data - the float data in row-major format.

Throws:

IllegalArgumentException - if data is null.

IllegalArgumentException - if width is not a positive number.

IllegalArgumentException - if height is not a positive number.

IllegalArgumentException - if data does not have width * height number of elements.

KernelJAI

public KernelJAI(Kernel k)

Constructs a KernelJAI from a java.awt.image.Kernel object.

Throws:

NullPointerException - if k is null.

Method Detail

getWidth

public int getWidth()

Returns the width of the kernel.

getHeight

public int getHeight()

Returns the height of the kernel.

getXOrigin

public int getXOrigin()

Returns the X coordinate of the key kernel element.

getYOrigin

public int getYOrigin()

Returns the Y coordinate of the key kernel element.

getKernelData

public float[] getKernelData()

Returns a copy of the kernel data in row-major format.

getHorizontalKernelData

public float[] getHorizontalKernelData()

Returns the horizontal portion of the kernel if the kernel is separable, or null otherwise. The kernel may be tested for separability by calling isSeparable().

getVerticalKernelData

public float[] getVerticalKernelData()

Returns the vertical portion of the kernel if the kernel is separable, or null otherwise. The kernel may be tested for separability by calling isSeparable().

getElement

public float getElement(int xIndex,
                        int yIndex)

Returns a given element of the kernel.

Throws:

ArrayIndexOutOfBoundsException - if either xIndex or yIndex is an invalid index.

isSeparable

public boolean isSeparable()

Returns true if the kernel is separable.

isHorizontallySymmetric

public boolean isHorizontallySymmetric()

Returns true if the kernel has horizontal (Y axis) symmetry.

isVerticallySymmetric

public boolean isVerticallySymmetric()

Returns true if the kernel has vertical (X axis) symmetry.

getLeftPadding

public int getLeftPadding()

Returns the number of pixels required to the left of the key element.

getRightPadding

public int getRightPadding()

Returns the number of pixels required to the right of the key element.

getTopPadding

public int getTopPadding()

Returns the number of pixels required above the key element.

getBottomPadding

public int getBottomPadding()

Returns the number of pixels required below the key element.

getRotatedKernel

public KernelJAI getRotatedKernel()

Returns a 180 degree rotated version of the kernel. This is needed by most convolve operations to get the correct results.

Returns:

the rotated kernel.