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

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkCompareHistogramImageToImageMetric.h,v $
  Language:  C++
  Date:      $Date: 2004/12/21 22:47:26 $
  Version:   $Revision: 1.6 $

  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 __itkCompareHistogramImageToImageMetric_h
#define __itkCompareHistogramImageToImageMetric_h

#include "itkHistogramImageToImageMetric.h"

namespace itk
{
  /** \class CompareHistogramImageToImageMetric
    *  \brief Compares Histograms between two images to be registered to
    *   a Training Histogram.
    *
    *  This class is templated over the type of the fixed and moving
    *  images to be compared. 
    *
    *  This metric computes the similarity between the histogram produced
    *  by two images overlapping and a training histogram.
    *
    *  It is to be sub-classed by the method of comparing the
    *  histograms.
    *
    *  Generally, the histogram from the training data is to be
    *  computed in exactly the same way as the histogram from the
    *  images to be compared are computed. Thus, the user can set the
    *  interpolator, region, two training images and the transfrom and
    *  the training histogram will be formed. OR, the user can simply
    *  calculate the training histogram seperately and set it.
    *
    * \warning The Initialize function does nothing if the training
    * histogram already exists. Thus repeated calls to the Initialize
    * function do nothing after the first call. If you wish the
    * training histogram to be re-calculated, you should set it to 0.
    *
    *  \author Samson Timoner.
    *
    *  \ingroup RegistrationMetrics */
template <class TFixedImage, class TMovingImage>
class ITK_EXPORT CompareHistogramImageToImageMetric :
public HistogramImageToImageMetric<TFixedImage, TMovingImage>
{
 public:
  /** Standard class typedefs. */
  typedef CompareHistogramImageToImageMetric Self;
  typedef HistogramImageToImageMetric<TFixedImage, TMovingImage> Superclass;
  typedef SmartPointer<Self>                                     Pointer;
  typedef SmartPointer<const Self>                               ConstPointer;

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

  /** Types transferred from the base class */
  typedef typename Superclass::RealType                 RealType;
  typedef typename Superclass::TransformType            TransformType;
  typedef typename Superclass::TransformPointer         TransformPointer;
  typedef typename TransformType::ConstPointer          TransformConstPointer;

  typedef typename Superclass::TransformParametersType
    TransformParametersType;
  typedef typename Superclass::TransformJacobianType    TransformJacobianType;
  typedef typename Superclass::GradientPixelType        GradientPixelType;

  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 Superclass::HistogramType            HistogramType;
  typedef typename Superclass::HistogramSizeType        HistogramSizeType;
  typedef typename HistogramType::MeasurementVectorType
    HistogramMeasurementVectorType;
  typedef typename HistogramType::FrequencyType         HistogramFrequencyType;
  typedef typename HistogramType::Iterator              HistogramIteratorType;
  typedef typename HistogramType::Pointer               HistogramPointerType;

  typedef typename Superclass::InterpolatorType InterpolatorType;
  typedef typename Superclass::InterpolatorPointer 
    InterpolatorPointer;

  typedef typename Superclass::FixedImageRegionType 
    FixedImageRegionType;

  /** Set the histogram to be used in the metric calculation */
  itkSetMacro( TrainingHistogram, HistogramPointerType );

  /** Get the histogram to be used in the metric calculation */
  itkGetConstReferenceMacro( TrainingHistogram, HistogramPointerType );

  /** Set the Training Fixed Image.  */
  itkSetConstObjectMacro( TrainingFixedImage, FixedImageType );

  /** Get the Training Fixed Image. */
  itkGetConstObjectMacro( TrainingFixedImage, FixedImageType );

  /** Set the Training Moving Image.  */
  itkSetConstObjectMacro( TrainingMovingImage, MovingImageType );

  /** Get the Training Moving Image. */
  itkGetConstObjectMacro( TrainingMovingImage, MovingImageType );

  /** Set the Training Transform. */
  itkSetObjectMacro( TrainingTransform, TransformType );

  /** Get a pointer to the Transform.  */
  itkGetObjectMacro( TrainingTransform, TransformType );

  /** Set the Interpolator. */
  itkSetObjectMacro( TrainingInterpolator, InterpolatorType );

  /** Get a pointer to the Interpolator.  */
  itkGetObjectMacro( TrainingInterpolator, InterpolatorType );

  /** Set the region over which the training histogram will be computed */
  itkSetMacro( TrainingFixedImageRegion, FixedImageRegionType );

  /** Get the region over which the training histogram will be computed */
  itkGetConstReferenceMacro( TrainingFixedImageRegion, FixedImageRegionType );

  /** Return the number of parameters required by the Transform */
  unsigned int GetNumberOfParameters(void) const 
  { return this->GetTransform()->GetNumberOfParameters(); }
 
  /** Forms the histogram of the training images to prepare to evaluate the */
  /** metric. Must set all parameters first. */
  void Initialize() throw (ExceptionObject);

protected:
  /** Constructor is protected to ensure that \c New() function is used to
      create instances. */
  CompareHistogramImageToImageMetric();
  virtual ~CompareHistogramImageToImageMetric(){}
  void PrintSelf(std::ostream& os, Indent indent) const;

  /** Form the Histogram for the Training data */
  void FormTrainingHistogram() throw (ExceptionObject);

  /** Evaluates the comparison histogram metric. All sub-classes must 
      re-implement method. */
  virtual MeasureType EvaluateMeasure(HistogramType& histogram) const = 0;

private:
  // Purposely not implemented.
  CompareHistogramImageToImageMetric(Self const&);
  void operator=(Self const&); // Purposely not implemented.

  FixedImageConstPointer  m_TrainingFixedImage;
  MovingImageConstPointer m_TrainingMovingImage;
  TransformPointer        m_TrainingTransform;
  InterpolatorPointer     m_TrainingInterpolator;
  FixedImageRegionType    m_TrainingFixedImageRegion;
  HistogramPointerType    m_TrainingHistogram;

};

} // End namespace itk.

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

#endif // __itkCompareHistogramImageToImageMetric_h
