Package gov.nih.mipav.model.algorithms.levelset

Class LseEvolve2

java.lang.Object

gov.nih.mipav.model.algorithms.levelset.LsePdeFilter

gov.nih.mipav.model.algorithms.levelset.LsePdeFilter2

gov.nih.mipav.model.algorithms.levelset.LseEvolve2

Direct Known Subclasses:

LseGeodesicActiveContour2, LseShapeDetection2, LseThreshold2

public abstract class LseEvolve2
extends LsePdeFilter2

The abstract base class for level-set evolution of 2D images. It is based on PDEs that are solved numerically using finite-difference approximations.

Version:

0.1 November 7, 2006

Author:

David Eberly

Field Summary

Fields

Modifier and Type	Field	Description
protected float[][]	m_aafD2	The second-order derivatives of the current pixel.
protected float[]	m_afAdvection	The advection for the current pixel.
protected float[]	m_afD1	The first-order derivatives of the current pixel.
protected float[]	m_afD1Bwd	Backward finite-difference approximations to the first-order derivatives of the current pixel.
protected float[]	m_afD1Fwd	Forward finite-difference approximations to the first-order derivatives of the current pixel.
protected float	m_fD0	The image value of the current pixel.
protected float	m_fGradMagSqr	The squared magnitude of the gradient vector for the current pixel.
protected LseParameters	m_kParameters	The parameters associated with level-set evolution.

Fields inherited from class gov.nih.mipav.model.algorithms.levelset.LsePdeFilter2

m_aabMask, m_aafDst, m_aafSrc, m_fFourthInvDxDy, m_fHalfInvDx, m_fHalfInvDy, m_fInvDx, m_fInvDxDx, m_fInvDy, m_fInvDyDy, m_fUmm, m_fUmp, m_fUmz, m_fUpm, m_fUpp, m_fUpz, m_fUzm, m_fUzp, m_fUzz, m_fXSpacing, m_fYSpacing, m_iXBound, m_iYBound

Fields inherited from class gov.nih.mipav.model.algorithms.levelset.LsePdeFilter

m_eScaleType, m_fBorderValue, m_fMin, m_fOffset, m_fScale, m_fTimeStep, m_iQuantity, NONE, PRESERVE_ZERO, SYMMETRIC, UNIT

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	LseEvolve2(int iXBound, int iYBound, float fXSpacing, float fYSpacing, float[] afData, boolean[] abMask, float fBorderValue, int eScaleType)	Create a new level-set evolver for 2D images.

Method Summary

Modifier and Type	Method	Description
protected float[]	computeAdvection(int iX, int iY)	Override this function to implement the desired advection for your level-set evolver.
protected float	computeCurvature(int iX, int iY)	Compute the product of length and curvature at the pixel (x,y).
protected float	computeCurvatureSpeed(int iX, int iY)	Override this function to implement the desired curvature speed for your level-set evolver.
protected float	computeFunction(int iX, int iY)	Evolution support.
protected float	computeLaplacianSpeed(int iX, int iY)	Override this function to implement the desired Laplacian speed for your level-set evolver.
protected float	computePropagationSpeed(int iX, int iY)	Override this function to implement the desired propagation speed for your level-set evolver.
LseParameters	getParameters()	Get the current level-set evolution parameters.
protected void	onPreUpdate()	The override of LsePdeFilter2.onPreUpdate.
protected void	onUpdate(int iX, int iY)	The override of LsePdeFilter2.onUpdate.

Methods inherited from class gov.nih.mipav.model.algorithms.levelset.LsePdeFilter2

assignDirichletImageBorder, assignDirichletMaskBorder, assignNeumannImageBorder, assignNeumannMaskBorder, getMask, getU, getUx, getUxx, getUxy, getUy, getUyy, getXBound, getXSpacing, getYBound, getYSpacing, lookUp5, lookUp9, onPostUpdate, onUpdate

Methods inherited from class gov.nih.mipav.model.algorithms.levelset.LsePdeFilter

getBorderValue, getQuantity, getScaleType, getTimeStep, setTimeStep, update

Methods inherited from class java.lang.Object

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

Field Detail

m_kParameters

protected LseParameters m_kParameters

The parameters associated with level-set evolution.

m_fD0

protected float m_fD0

The image value of the current pixel.

m_afD1

protected float[] m_afD1

The first-order derivatives of the current pixel.

m_aafD2

protected float[][] m_aafD2

The second-order derivatives of the current pixel.

m_afD1Fwd

protected float[] m_afD1Fwd

Forward finite-difference approximations to the first-order derivatives of the current pixel.

m_afD1Bwd

protected float[] m_afD1Bwd

Backward finite-difference approximations to the first-order derivatives of the current pixel.

m_fGradMagSqr

protected float m_fGradMagSqr

The squared magnitude of the gradient vector for the current pixel.

m_afAdvection

protected float[] m_afAdvection

The advection for the current pixel.

Constructor Detail

LseEvolve2

protected LseEvolve2(int iXBound,
                     int iYBound,
                     float fXSpacing,
                     float fYSpacing,
                     float[] afData,
                     boolean[] abMask,
                     float fBorderValue,
                     int eScaleType)

Create a new level-set evolver for 2D images.

Parameters:

iXBound - The x-bound of the image.

iYBound - The y-bound of the image.

fXSpacing - The x-spacing of the image.

fYSpacing - The y-spacing of the image.

afData - The image elements, stored in lexicographical order.

abMask - The image mask, stored in lexicographical order. A pixel value is processed by the PDE solver only when the mask value is false.

fBorderValue - Specifies how to handle the image value. When set to Float.MAX_VALUE, Neumann conditions are in use, in which case zero-valued derivatives are assumed on the image border. Otherwise, Dirichlet conditions are used, in which case the image is assumed to be constant on the border with value specified by fBorderValue.

eScaleType - The type of scaling to apply to the input image. The choices are NONE, UNIT, SYMMETRIC, or PRESERVE_ZERO.

Method Detail

getParameters

public final LseParameters getParameters()

Get the current level-set evolution parameters.

Returns:

The current level-set evolution parameters.

computeFunction

protected final float computeFunction(int iX,
                                      int iY)

Evolution support. ComputeTimeStep() is called each time before ComputeFunction() is called. The function ComputeCurvature() actually computes k*L, where k is the curvature and L is the length of the gradient vector. The resulting quantity is

k*L = (Uxx*Uy*Uy - 2*Uxy*Ux*Uy + Uyy*Ux*Ux)/(Ux*Ux + Uy*Uy)

where Ux and Uy are first-order partial derivatives and Uxx, Uxy, and Uyy are second-order partial derivatives.

Parameters:

iX - The x-coordinate of the pixel.

iY - The y-coordinate of the pixel.

Returns:

The value of the right-hand side of the PDE that governs the level-set evolution.

computeCurvature

protected final float computeCurvature(int iX,
                                       int iY)

Compute the product of length and curvature at the pixel (x,y).

Parameters:

iX - The x-coordinate of the pixel.

iY - The y-coordinate of the pixel.

Returns:

The product of length and curvature at the pixel.

computeAdvection

protected float[] computeAdvection(int iX,
                                   int iY)

Override this function to implement the desired advection for your level-set evolver.

Parameters:

iX - The x-coordinate of the pixel.

iY - The y-coordinate of the pixel.

Returns:

The advection at the pixel.

computePropagationSpeed

protected float computePropagationSpeed(int iX,
                                        int iY)

Override this function to implement the desired propagation speed for your level-set evolver.

Parameters:

iX - The x-coordinate of the pixel.

iY - The y-coordinate of the pixel.

Returns:

The propagation speed at the pixel.

computeCurvatureSpeed

protected float computeCurvatureSpeed(int iX,
                                      int iY)

Override this function to implement the desired curvature speed for your level-set evolver.

Parameters:

iX - The x-coordinate of the pixel.

iY - The y-coordinate of the pixel.

Returns:

The curvature speed at the pixel.

computeLaplacianSpeed

protected float computeLaplacianSpeed(int iX,
                                      int iY)

Override this function to implement the desired Laplacian speed for your level-set evolver.

Parameters:

iX - The x-coordinate of the pixel.

iY - The y-coordinate of the pixel.

Returns:

The Laplacian speed at the pixel.

onPreUpdate

protected void onPreUpdate()

The override of LsePdeFilter2.onPreUpdate. This is where ComputeTimeStep is called.

Overrides:

onPreUpdate in class LsePdeFilter2

onUpdate

protected void onUpdate(int iX,
                        int iY)

The override of LsePdeFilter2.onUpdate. This is where ComputeFunction is called.

Specified by:

onUpdate in class LsePdeFilter2

Parameters:

iX - The x-coordinate of the pixel.

iY - The y-coordinate of the pixel.