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 Details

    • 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 Details

    • 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 Details

    • 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.