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

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkESMDemonsRegistrationFunction.h,v $
  Language:  C++
  Date:      $Date: 2008-07-04 22:54:43 $
  Version:   $Revision: 1.2 $

  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 __itkVectorESMDemonsRegistrationFunction_h
#define __itkVectorESMDemonsRegistrationFunction_h

#include "itkPDEDeformableRegistrationFunction.h"
#include "itkPoint.h"
#include "itkCovariantVector.h"
#include "itkInterpolateImageFunction.h"
#include "itkLinearInterpolateImageFunction.h"
#include "itkCentralDifferenceImageFunction.h"
#include "itkWarpImageFilter.h"
#include "itkVectorImageToImageAdaptor.h"

namespace itk
{
/**
 * \class ESMDemonsRegistrationFunction
 *
 * \brief Fast implementation of the symmetric demons registration force
 *
 * This class provides a substantially faster implementation of the
 * symmetric demons registration force. Speed is improved by keeping
 * a deformed copy of the moving image for gradient evaluation.
 *
 * Symmetric forces simply means using the mean of the gradient
 * of the fixed image and the gradient of the warped moving
 * image.
 *
 * Note that this class also enables the use of fixed, mapped moving
 * and warped moving images forces by using a call to SetUseGradientType
 *
 * The moving image should not be saturated. We indeed use
 * NumericTraits<MovingPixelType>::Max() as a special value.
 *
 * \author Tom Vercauteren, INRIA & Mauna Kea Technologies
 *
 * This implementation was taken from the Insight Journal paper:
 * http://hdl.handle.net/1926/510
 *
 * \sa SymmetricForcesDemonsRegistrationFunction
 * \sa SymmetricForcesDemonsRegistrationFilter
 * \sa DemonsRegistrationFilter
 * \sa DemonsRegistrationFunction
 * \ingroup FiniteDifferenceFunctions
 *
 */
template <class TFixedImage, class TMovingImage, class TDeformationField>
class ITK_EXPORT VectorESMDemonsRegistrationFunction :
  public PDEDeformableRegistrationFunction<TFixedImage,
    TMovingImage, TDeformationField>
  {
public:
  /** Standard class typedefs. */
  typedef VectorESMDemonsRegistrationFunction Self;
  typedef PDEDeformableRegistrationFunction<
    TFixedImage, TMovingImage, TDeformationField>    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( VectorESMDemonsRegistrationFunction,
    PDEDeformableRegistrationFunction );

  /** MovingImage image type. */
  typedef TMovingImage                                 VectorMovingImageType;
  typedef typename VectorMovingImageType::ConstPointer VectorMovingImagePointer;

  /** FixedImage image type. */
  typedef TFixedImage                                 VectorFixedImageType;
  typedef typename VectorFixedImageType::ConstPointer VectorFixedImagePointer;

  /** Inherit some enums from the superclass. */
  itkStaticConstMacro(ImageDimension, unsigned int, Superclass::ImageDimension);

  /** MovingImage image type. */
  //  typedef typename Superclass::MovingImageType      MovingImageType;
  typedef  itk::Image<float,itkGetStaticConstMacro(ImageDimension) >               MovingImageType;
  //  typedef typename Superclass::MovingImagePointer   MovingImagePointer;
  typedef  typename MovingImageType::Pointer           MovingImagePointer;
  typedef typename MovingImageType::PixelType MovingPixelType;

  /** FixedImage image type. */
  //  typedef typename Superclass::FixedImageType       FixedImageType;
  typedef itk::Image<float, itkGetStaticConstMacro(ImageDimension)>                   FixedImageType;
  typedef typename  FixedImageType::Pointer               FixedImagePointer;
  //  typedef typename Superclass::FixedImagePointer    FixedImagePointer;
  typedef typename FixedImageType::IndexType     IndexType;
  typedef typename FixedImageType::SizeType      SizeType;
  typedef typename FixedImageType::SpacingType   SpacingType;
  typedef typename FixedImageType::DirectionType DirectionType;

  /** Deformation field type. */
  typedef typename Superclass::DeformationFieldType DeformationFieldType;
  typedef typename Superclass::DeformationFieldTypePointer
  DeformationFieldTypePointer;

    /** Inherit some enums from the superclass. */
  typedef typename Superclass::PixelType                     PixelType;
  typedef typename Superclass::RadiusType                    RadiusType;
  typedef typename Superclass::NeighborhoodType              NeighborhoodType;
  typedef typename Superclass::FloatOffsetType               FloatOffsetType;
  typedef typename Superclass::TimeStepType                  TimeStepType;

  typedef itk::VectorImageToImageAdaptor<MovingPixelType, itkGetStaticConstMacro(ImageDimension)> AdaptorType;

  /** Interpolator type. */
  typedef double CoordRepType;
  typedef InterpolateImageFunction<
    AdaptorType, CoordRepType>                   InterpolatorType;
  typedef typename InterpolatorType::Pointer   InterpolatorPointer;
  typedef typename InterpolatorType::PointType PointType;
  typedef LinearInterpolateImageFunction<
    AdaptorType, CoordRepType>                   DefaultInterpolatorType;

  /** Warper type */
  typedef WarpImageFilter<
    AdaptorType,
    MovingImageType, DeformationFieldType>           WarperType;
  typedef typename WarperType::Pointer WarperPointer;

  /** Covariant vector type. */
  typedef CovariantVector<double,
    itkGetStaticConstMacro(ImageDimension)>
  CovariantVectorType;

  /** Fixed image gradient calculator type. */
  typedef CentralDifferenceImageFunction<AdaptorType> GradientCalculatorType;
  typedef typename GradientCalculatorType::Pointer    GradientCalculatorPointer;

  /** Moving image gradient (unwarped) calculator type. */
  typedef CentralDifferenceImageFunction<AdaptorType, CoordRepType>
  MovingImageGradientCalculatorType;
  typedef typename MovingImageGradientCalculatorType::Pointer
  MovingImageGradientCalculatorPointer;

  /** Set the moving image interpolator. */
  void SetMovingImageInterpolator( InterpolatorType *ptr )
  {
    m_MovingImageInterpolator = ptr; m_MovingImageWarper->SetInterpolator( ptr );
  }

  /** Get the moving image interpolator. */
  InterpolatorType * GetMovingImageInterpolator(void)
  {
    return m_MovingImageInterpolator;
  }

  /** This class uses a constant timestep of 1. */
  virtual TimeStepType ComputeGlobalTimeStep( void *itkNotUsed(GlobalData) )
  const
  {
    return m_TimeStep;
  }

  /** Return a pointer to a global data structure that is passed to
   * this object from the solver at each calculation.  */
  virtual void * GetGlobalDataPointer() const
  {
    GlobalDataStruct *global = new GlobalDataStruct();

    global->m_SumOfSquaredDifference  = 0.0;
    global->m_NumberOfPixelsProcessed = 0L;
    global->m_SumOfSquaredChange      = 0;
    return global;
  }

  /** Release memory for global data structure. */
  virtual void ReleaseGlobalDataPointer( void *GlobalData ) const;

  /** Set the object's state before each iteration. */
  virtual void InitializeIteration();

  /** This method is called by a finite difference solver image filter at
   * each pixel that does not lie on a data set boundary */
  virtual PixelType  ComputeUpdate(
    const NeighborhoodType & neighborhood,
    void *globalData,
    const FloatOffsetType & offset
      = FloatOffsetType(0.0) );

  /** Get the metric value. The metric value is the mean square difference
   * in intensity between the fixed image and transforming moving image
   * computed over the the overlapping region between the two images. */
  virtual double GetMetric() const
  {
    return m_Metric;
  }

  /** Get the rms change in deformation field. */
  virtual const double & GetRMSChange() const
  {
    return m_RMSChange;
  }

  /** Set/Get the threshold below which the absolute difference of
   * intensity yields a match. When the intensities match between a
   * moving and fixed image pixel, the update vector (for that
   * iteration) will be the zero vector. Default is 0.001. */
  virtual void SetIntensityDifferenceThreshold(double);

  virtual double GetIntensityDifferenceThreshold() const;

  /** Set/Get the maximum update step length. In Thirion this is 0.5.
   *  Setting it to 0 implies no restriction (beware of numerical
   *  instability in this case. */
  virtual void SetMaximumUpdateStepLength(double sm)
  {
    this->m_MaximumUpdateStepLength = sm;
  }

  virtual double GetMaximumUpdateStepLength() const
  {
    return this->m_MaximumUpdateStepLength;
  }

  /** Type of available image forces */
  enum GradientType {
    Symmetric = 0,
    Fixed,
    WarpedMoving,
    MappedMoving
    };

  /** Set/Get the type of used image forces */
  virtual void SetUseGradientType( GradientType gtype )
  {
    m_UseGradientType = gtype;
  }

  virtual GradientType GetUseGradientType() const
  {
    return m_UseGradientType;
  }

  /** Set the moving image.  */
  void SetMovingImage( const VectorMovingImageType *ptr )
  {
    m_MovingImage = ptr;
  }

  /** Get the moving image. */
  const VectorMovingImageType * GetMovingImage(void) const
  {
    return m_MovingImage;
  }

  /** Set the fixed image. */
  void SetFixedImage( const VectorFixedImageType *ptr )
  {
    m_FixedImage = ptr;
  }

  /** Get the fixed image. */
  const VectorFixedImageType * GetFixedImage(void) const
  {
    return m_FixedImage;
  }

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

  /** FixedImage image neighborhood iterator type. */
  typedef ConstNeighborhoodIterator<FixedImageType>
  FixedImageNeighborhoodIteratorType;

  /** A global data type for this class of equation. Used to store
   * iterators for the fixed image. */
  struct GlobalDataStruct {
    double m_SumOfSquaredDifference;
    unsigned long m_NumberOfPixelsProcessed;
    double m_SumOfSquaredChange;
    };
private:
  VectorESMDemonsRegistrationFunction(const Self &); // purposely not
                                                     // implemented
  void operator=(const Self &);                      // purposely not

  // implemented

  VectorFixedImagePointer  m_FixedImage;
  VectorMovingImagePointer m_MovingImage;

  /** Cache fixed image information. */
  SpacingType   m_FixedImageSpacing;
  PointType     m_FixedImageOrigin;
  DirectionType m_FixedImageDirection;
  double        m_Normalizer;

  /** Function to compute derivatives of the fixed image. */
  GradientCalculatorPointer m_FixedImageGradientCalculator;

  /** Function to compute derivatives of the moving image (unwarped). */
  MovingImageGradientCalculatorPointer m_MappedMovingImageGradientCalculator;

  GradientType m_UseGradientType;

  /** Function to interpolate the moving image. */
  InterpolatorPointer m_MovingImageInterpolator;

  /** Filter to warp moving image for fast gradient computation. */
  WarperPointer m_MovingImageWarper;

  /** The global timestep. */
  TimeStepType m_TimeStep;

  /** Threshold below which the denominator term is considered zero. */
  double m_DenominatorThreshold;

  /** Threshold below which two intensity value are assumed to match. */
  double m_IntensityDifferenceThreshold;

  /** Maximum update step length in pixels (default is 0.5 as in Thirion). */
  double m_MaximumUpdateStepLength;

  /** The metric value is the mean square difference in intensity between
   * the fixed image and transforming moving image computed over the
   * the overlapping region between the two images. */
  mutable double m_Metric;
  mutable double m_SumOfSquaredDifference;
  mutable unsigned long m_NumberOfPixelsProcessed;
  mutable double m_RMSChange;
  mutable double m_SumOfSquaredChange;

  /** Mutex lock to protect modification to metric. */
  mutable SimpleFastMutexLock m_MetricCalculationLock;

  std::vector<WarperPointer>       m_MovingImageWarperVector;
  std::vector<InterpolatorPointer> m_MovingImageInterpolatorVector;
  std::vector<GradientCalculatorPointer>                    m_FixedImageGradientCalculatorVector;
  std::vector<MovingImageGradientCalculatorPointer>         m_MappedMovingImageGradientCalculatorVector;
  };
} // end namespace itk

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

#endif
