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

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkGaussianBlurImageFunction.h,v $
  Language:  C++
  Date:      $Date: 2006/02/06 22:01:55 $
  Version:   $Revision: 1.10 $

  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 );
  itkGetMacro( 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 );
  itkGetMacro( 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:
  
  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

#ifndef ITK_MANUAL_INSTANTIATION
#include "itkGaussianBlurImageFunction.txx"
#endif

#endif

