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

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkGradientDifferenceImageToImageMetric.h,v $
  Language:  C++
  Date:      $Date: 2005/12/01 18:42:20 $
  Version:   $Revision: 1.7 $

  Copyright (c) 2002 Insight 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 __itkGradientDifferenceImageToImageMetric_h
#define __itkGradientDifferenceImageToImageMetric_h

#include "itkImageToImageMetric.h"

#include "itkSobelOperator.h"
#include "itkNeighborhoodOperatorImageFilter.h"
#include "itkPoint.h"
#include "itkCastImageFilter.h"
#include "itkResampleImageFilter.h"

namespace itk
{
/** \class GradientDifferenceImageToImageMetric
 * \brief Computes similarity between two objects to be registered
 *
 * This Class is templated over the type of the Images to be compared and
 * over the type of transformation and Iterpolator to be used.
 *
 * This metric computes the sum of squared differences between pixels in
 * the derivatives of the moving and fixed images after passing the squared
 * difference through a function of type \f$ \frac{1}{1+x} \f$.

 * Spatial correspondance between both images is established through a 
 * Transform. Pixel values are taken from the Moving image. Their positions 
 * are mapped to the Fixed image and result in general in non-grid position 
 * on it. Values at these non-grid position of the Fixed image are
 * interpolated using a user-selected Interpolator.
 *
 * Implementation of this class is based on:
 * Hipwell, J. H., et. al. (2003), "Intensity-Based 2-D-3D Registration of
 * Cerebral Angiograms,", IEEE Transactions on Medical Imaging,
 * 22(11):1417-1426.
 * 
 * \ingroup RegistrationMetrics
 */
template < class TFixedImage, class TMovingImage > 
class ITK_EXPORT GradientDifferenceImageToImageMetric : 
public ImageToImageMetric< TFixedImage, TMovingImage>
{
public:

  /** Standard class typedefs. */
  typedef GradientDifferenceImageToImageMetric    Self;
  typedef ImageToImageMetric<TFixedImage, TMovingImage >  Superclass;

  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(GradientDifferenceImageToImageMetric, ImageToImageMetric);

 
  /** Types transferred from the base class */
// Work around a Visual Studio .NET bug
#if defined(_MSC_VER) && (_MSC_VER == 1300)
  typedef double RealType;
#else
  typedef typename Superclass::RealType                 RealType;
#endif
  typedef typename Superclass::TransformType            TransformType;
  typedef typename Superclass::TransformPointer         TransformPointer;
  typedef typename Superclass::TransformParametersType  TransformParametersType;
  typedef typename Superclass::TransformJacobianType    TransformJacobianType;

  typedef typename Superclass::MeasureType              MeasureType;
  typedef typename Superclass::DerivativeType           DerivativeType;
  typedef typename Superclass::FixedImageType           FixedImageType;
  typedef typename Superclass::MovingImageType          MovingImageType;
  typedef typename Superclass::FixedImageConstPointer   FixedImageConstPointer;
  typedef typename Superclass::MovingImageConstPointer  MovingImageConstPointer;

  typedef typename TFixedImage::PixelType               FixedImagePixelType;
  typedef typename TMovingImage::PixelType              MovedImagePixelType;

  itkStaticConstMacro(FixedImageDimension, unsigned int, TFixedImage::ImageDimension);
  /** Types for transforming the moving image */
  typedef itk::Image< FixedImagePixelType, 
                      itkGetStaticConstMacro( FixedImageDimension ) >      
                    TransformedMovingImageType;

  typedef itk::ResampleImageFilter< MovingImageType, TransformedMovingImageType >  
                                                        TransformMovingImageFilterType;

  /** Sobel filters to compute the gradients of the Fixed Image */

  typedef itk::Image< RealType, 
                      itkGetStaticConstMacro( FixedImageDimension ) >
                    FixedGradientImageType;

  typedef itk::CastImageFilter< FixedImageType, FixedGradientImageType > 
                                                      CastFixedImageFilterType;
  typedef typename CastFixedImageFilterType::Pointer CastFixedImageFilterPointer;

  typedef typename FixedGradientImageType::PixelType FixedGradientPixelType;


  /** Sobel filters to compute the gradients of the Moved Image */

  itkStaticConstMacro( MovedImageDimension, unsigned int,
                       MovingImageType::ImageDimension );

  typedef itk::Image< RealType,
                      itkGetStaticConstMacro( MovedImageDimension ) >
                    MovedGradientImageType;

  typedef itk::CastImageFilter< TransformedMovingImageType, MovedGradientImageType > 
                                                     CastMovedImageFilterType;
  typedef typename CastMovedImageFilterType::Pointer CastMovedImageFilterPointer;

  typedef typename MovedGradientImageType::PixelType MovedGradientPixelType;


  /** Get the derivatives of the match measure. */
  void GetDerivative( const TransformParametersType & parameters,
                            DerivativeType  & derivative ) const;

  /**  Get the value for single valued optimizers. */
  MeasureType GetValue( const TransformParametersType & parameters ) const;

  /**  Get value and derivatives for multiple valued optimizers. */
  void GetValueAndDerivative( const TransformParametersType & parameters,
                              MeasureType& Value, DerivativeType& derivative ) const;

  /** Initialize the Metric by making sure that all the components
   *  are present and plugged together correctly     */
  virtual void Initialize(void) throw ( ExceptionObject );

  /** Write gradient images to a files for debugging purposes. */
  void WriteGradientImagesToFiles(void) const;

protected:
  GradientDifferenceImageToImageMetric();
  virtual ~GradientDifferenceImageToImageMetric() {};
  void PrintSelf(std::ostream& os, Indent indent) const;

  /** Compute the range of the moved image gradients. */
  void ComputeMovedGradientRange( void ) const;

   /** Compute the variance and range of the moving image gradients. */
  void ComputeVariance( void ) const;

  /** Compute the similarity measure using a specified subtraction factor. */
  MeasureType ComputeMeasure( const TransformParametersType &parameters,
                              const double *subtractionFactor ) const;

  typedef NeighborhoodOperatorImageFilter<
    FixedGradientImageType, FixedGradientImageType > FixedSobelFilter;

  typedef NeighborhoodOperatorImageFilter<
    MovedGradientImageType, MovedGradientImageType > MovedSobelFilter;

private:
  GradientDifferenceImageToImageMetric(const Self&); //purposely not implemented
  void operator=(const Self&); //purposely not implemented

  /** The variance of the moving image gradients. */
  mutable MovedGradientPixelType m_Variance[FixedImageDimension];

  /** The range of the moving image gradients. */
  mutable MovedGradientPixelType m_MinMovedGradient[MovedImageDimension];
  mutable MovedGradientPixelType m_MaxMovedGradient[MovedImageDimension];
  /** The range of the fixed image gradients. */
  mutable FixedGradientPixelType m_MinFixedGradient[FixedImageDimension];
  mutable FixedGradientPixelType m_MaxFixedGradient[FixedImageDimension];

  /** The filter for transforming the moving image. */
  typename TransformMovingImageFilterType::Pointer m_TransformMovingImageFilter;

  /** The Sobel gradients of the fixed image */
  CastFixedImageFilterPointer m_CastFixedImageFilter;

  SobelOperator< FixedGradientPixelType, 
                 itkGetStaticConstMacro(FixedImageDimension) >
               m_FixedSobelOperators[FixedImageDimension];

  typename FixedSobelFilter::Pointer m_FixedSobelFilters[itkGetStaticConstMacro( FixedImageDimension )];

  ZeroFluxNeumannBoundaryCondition< MovedGradientImageType > m_MovedBoundCond;
  ZeroFluxNeumannBoundaryCondition< FixedGradientImageType > m_FixedBoundCond;

  /** The Sobel gradients of the moving image */
  CastMovedImageFilterPointer m_CastMovedImageFilter;

  SobelOperator< MovedGradientPixelType, 
                 itkGetStaticConstMacro(MovedImageDimension) >
               m_MovedSobelOperators[MovedImageDimension];

  typename MovedSobelFilter::Pointer m_MovedSobelFilters[itkGetStaticConstMacro( MovedImageDimension )];

};

} // end namespace itk

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

#endif



