itkGaussianBlurImageFunction.h

/*=========================================================================

  Program:   Insight Segmentation & Registration Toolkit
  Module:    itkGaussianBlurImageFunction.h
  Language:  C++
  Date:      $Date$
  Version:   $Revision$

  Copyright (c) Insight Software Consortium. All rights reserved.
  See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notices for more information.

=========================================================================*/
#ifndef __itkGaussianBlurImageFunction_h
#define __itkGaussianBlurImageFunction_h

#include "itkNeighborhoodOperatorImageFunction.h"
#include "itkGaussianOperator.h"
#include "itkGaussianSpatialFunction.h"
#include "itkImageFunction.h"
#include "itkCastImageFilter.h"

namespace itk
{

/**
 * \class GaussianBlurImageFunction
 * \brief Compute the convolution of a neighborhood operator with the image
 *        at a specific location in space, i.e. point, index or continuous
 *        index.
 * This class is templated over the input image type.
 * \sa NeighborhoodOperator
 * \sa ImageFunction
 */
template <class TInputImage,class TOutput=double>
class ITK_EXPORT GaussianBlurImageFunction :
  public ImageFunction< TInputImage, TOutput >
{
public:

  /**Standard "Self" typedef */
  typedef GaussianBlurImageFunction Self;

  /** Standard "Superclass" typedef */
  typedef ImageFunction<TInputImage, TOutput> Superclass;

  /** Smart pointer typedef support. */
  typedef SmartPointer<Self>          Pointer;
  typedef SmartPointer<const Self>    ConstPointer;

  /** Method for creation through the object factory. */
  itkNewMacro(Self);

  /** Run-time type information (and related methods). */
  itkTypeMacro( GaussianBlurImageFunction, ImageFunction );

  /** InputImageType typedef support. */
  typedef TInputImage                                 InputImageType;
  typedef typename InputImageType::PixelType          InputPixelType;
  typedef typename Superclass::IndexType              IndexType;
  typedef typename Superclass::ContinuousIndexType    ContinuousIndexType;


  /** Dimension of the underlying image. */
  itkStaticConstMacro(ImageDimension, unsigned int, InputImageType::ImageDimension);

  typedef GaussianOperator<
    TOutput, itkGetStaticConstMacro(ImageDimension)>                            GaussianOperatorType;
  typedef Neighborhood<TOutput, itkGetStaticConstMacro(ImageDimension)>         NeighborhoodType;
  typedef FixedArray<NeighborhoodType,itkGetStaticConstMacro(ImageDimension)>   OperatorArrayType;

  typedef GaussianSpatialFunction<TOutput,1>                                    GaussianFunctionType;
  typedef typename GaussianFunctionType::Pointer                                GaussianFunctionPointer;
  typedef itk::Image<double,itkGetStaticConstMacro(ImageDimension)>             InternalImageType;
  typedef typename InternalImageType::Pointer                                   InternalImagePointer;

  typedef NeighborhoodOperatorImageFunction< InternalImageType, TOutput>        OperatorImageFunctionType;
  typedef typename OperatorImageFunctionType::Pointer                           OperatorImageFunctionPointer;

  typedef itk::CastImageFilter<InputImageType,InternalImageType>                CastImageFilterType;
  typedef typename CastImageFilterType::Pointer                                 CastImageFilterPointer;

  typedef itk::FixedArray< double, itkGetStaticConstMacro(ImageDimension) >     ErrorArrayType;
  typedef itk::FixedArray< double, itkGetStaticConstMacro(ImageDimension) >     ExtentArrayType;
  typedef itk::FixedArray< double, itkGetStaticConstMacro(ImageDimension) >     SigmaArrayType;

  /** Point typedef support. */
  typedef typename Superclass::PointType PointType;

  /** Evalutate the  in the given dimension at specified point */
   virtual TOutput Evaluate(const PointType& point) const;


  /** Evaluate the function at specified Index position */
  virtual TOutput EvaluateAtIndex( const IndexType & index ) const;

  /** Evaluate the function at specified ContinousIndex position. */
  virtual TOutput EvaluateAtContinuousIndex(
    const ContinuousIndexType & index ) const;

  /** The standard deviation for the discrete Gaussian kernel.  Sets the
   * standard deviation independently for each dimension.
   * The default is 1.0 in each dimension.
   * If UseImageSpacing is true (default), the units are the physical units
   * of your image.  If UseImageSpacing is false then the units are pixels.
   */
  void SetSigma( const double* sigma);
  void SetSigma( const float* sigma);
  void SetSigma( const double sigma);
  itkSetMacro( Sigma, SigmaArrayType );
  itkGetConstReferenceMacro( Sigma, SigmaArrayType );

  /** Set the input image.
   * \warning this method caches BufferedRegion information.
   * If the BufferedRegion has changed, user must call
   * SetInputImage again to update cached values. */
  virtual void SetInputImage( const InputImageType * ptr );

  /** Set/Get the Extent of the array holding the coefficients
   *  of the Gaussian kernel computed by the GaussianOperator.
   */
  itkSetMacro( Extent, ExtentArrayType );
  itkGetConstReferenceMacro( Extent, ExtentArrayType );
  void SetExtent( const double* extent);
  void SetExtent( const double extent);

  /** Set/Get the maximum error acceptable for the approximation
   *  of the Gaussian kernel with the GaussianOperator.
   */
  itkSetMacro( MaximumError, ErrorArrayType );
  itkGetConstReferenceMacro( MaximumError, ErrorArrayType );

  /** Set/GetMaximumKernelWidth() This value is used by the underling
   *  GaussianOperator for computing the number of coefficients to be
   *  used in the Gaussian kernel
   */
  itkSetMacro( MaximumKernelWidth, int );
  itkGetConstMacro( MaximumKernelWidth, int );

  /** Set/GetUseImageSpacing() This flag is used by the underling
   *  GaussianOperator to decide if the image spacing should be used
   *  to scale the value of sigma or not. The methods UseImageSpacingOn()
   *  and UseImageSpacingOff() provide a similar functionality.
   */
  itkSetMacro( UseImageSpacing, bool );
  itkGetConstMacro( UseImageSpacing, bool );
  itkBooleanMacro( UseImageSpacing );


protected:
  GaussianBlurImageFunction();
  GaussianBlurImageFunction( const Self& ){};

  ~GaussianBlurImageFunction(){};

  void operator=( const Self& ){};
  void PrintSelf(std::ostream& os, Indent indent) const;

  void RecomputeGaussianKernel();
  void RecomputeContinuousGaussianKernel(const double* offset) const;

private:

  virtual TOutput EvaluateAtIndex( 
    const IndexType & index, const OperatorArrayType & operatorArray ) const;

  SigmaArrayType                m_Sigma;
  OperatorImageFunctionPointer  m_OperatorImageFunction;
  mutable OperatorArrayType     m_OperatorArray;
  mutable OperatorArrayType     m_ContinuousOperatorArray;
  InternalImagePointer          m_InternalImage;
  CastImageFilterPointer        m_Caster;

  /** The maximum error of the gaussian blurring kernel in each dimensional
   * direction. For definition of maximum error, see GaussianOperator.
   * \sa GaussianOperator */
  ErrorArrayType                m_MaximumError;
  ExtentArrayType               m_Extent;

  /** Maximum allowed kernel width for any dimension of the discrete Gaussian
      approximation */
  int m_MaximumKernelWidth;

  /** Number of dimensions to process. Default is all dimensions */
  unsigned int m_FilterDimensionality;

  /** Flag to indicate whether to use image spacing */
  bool m_UseImageSpacing;

  /** Neighborhood Image Function */
  GaussianFunctionPointer m_GaussianFunction;
};

} // end namespace itk

// Define instantiation macro for this template.
#define ITK_TEMPLATE_GaussianBlurImageFunction(_, EXPORT, x, y) namespace itk { \
  _(2(class EXPORT GaussianBlurImageFunction< ITK_TEMPLATE_2 x >)) \
  namespace Templates { typedef GaussianBlurImageFunction< ITK_TEMPLATE_2 x > \
                                                  GaussianBlurImageFunction##y; } \
  }

#if ITK_TEMPLATE_EXPLICIT
# include "Templates/itkGaussianBlurImageFunction+-.h"
#endif

#if ITK_TEMPLATE_TXX
# include "itkGaussianBlurImageFunction.txx"
#endif

#endif