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

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkMultiResolutionPyramidImageFilter.h,v $
  Language:  C++
  Date:      $Date: 2006/04/05 13:59:36 $
  Version:   $Revision: 1.18 $

  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 __itkMultiResolutionPyramidImageFilter_h
#define __itkMultiResolutionPyramidImageFilter_h

#include "itkImageToImageFilter.h"
#include "itkArray2D.h"

namespace itk
{

/** \class MultiResolutionPyramidImageFilter
 * \brief Framework for creating images in a multi-resolution
 * pyramid.
 *
 * MultiResolutionPyramidImageFilter provides a generic framework to
 * to create a image pryamid according to a user defined 
 * multi-resolution schedule.
 * 
 * The multi-resolution schedule is specified in terms for
 * shrink factors at each multi-resolution level for each dimension.
 * 
 * A user can either use the default schedules or specify 
 * each factor in the schedules directly.
 *
 * The schedule is stored as an unsigned int matrix.
 * An element of the table can be access via the double bracket
 * notation: table[resLevel][dimension]
 *
 * For example:
 *   8 4 4
 *   4 4 2
 *
 * is a schedule for two computation level. In the first (coarest)
 * level the image is reduce by a factor of 8 in the column dimension,
 * factor of 4 in the row dimension and factor of 4 in the slice dimension.
 * In the second level, the image is reduce by a factor of 4 in the column
 * dimension, 4 is the row dimension and 2 in the slice dimension.
 * 
 * The method SetNumberOfLevels() set the number of
 * computation levels in the pyramid. This method will
 * allocate memory for the multi-resolution schedule table.
 * This method generates defaults tables with the starting
 * shrink factor for all dimension set to  2^(NumberOfLevel - 1). 
 * All factors are halved for all subsequent levels. 
 * For example if the number of levels was set to 4, the default table is:
 *
 * 8 8 8
 * 4 4 4
 * 2 2 2
 * 1 1 1
 *
 * The user can get a copy of the schedule via GetSchedule()
 * They may make alteration and reset it using SetSchedule().
 *
 * A user can create a default table by specifying the starting
 * shrink factors via methods SetStartingShrinkFactors()
 * The factors for subsequent level is generated by 
 * halving the factor or setting to one, depending on which is larger.
 *
 * For example, for 4 levels and starting factors of 8,8,4
 * the default table would be:
 *
 * 8 8 4
 * 4 4 2
 * 2 2 1
 * 1 1 1
 *
 * When this filter is updated, NumberOfLevels outputs are produced.
 * The N'th output correspond to the N'th level of the pyramid.
 * 
 * To generate each output image, Gaussian smoothing is first performed 
 * using a DiscreteGaussianImageFilter with variance (shrink factor / 2)^2. 
 * The smoothed image is then downsampled using a ShrinkImageFiter.
 *
 * This class is templated over the input image type and the output image 
 * type.
 *
 * This filter uses multithreaded filters to perform the smoothing and
 * downsampling.
 *
 * This filter supports streaming.
 *
 * \sa DiscreteGaussianImageFilter
 * \sa ShrinkImageFilter
 *
 * \ingroup PyramidImageFilter Multithreaded Streamed
 */
template <
  class TInputImage, 
  class TOutputImage
  >
class ITK_EXPORT MultiResolutionPyramidImageFilter : 
    public ImageToImageFilter< TInputImage, TOutputImage >
{
public:
  /** Standard class typedefs. */
  typedef MultiResolutionPyramidImageFilter  Self;
  typedef ImageToImageFilter<TInputImage,TOutputImage>  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(MultiResolutionPyramidImageFilter, ImageToImageFilter);

  /** ScheduleType typedef support. */
  typedef Array2D<unsigned int>  ScheduleType;

  /** ImageDimension enumeration. */
  itkStaticConstMacro(ImageDimension, unsigned int,
                      TInputImage::ImageDimension);
  itkStaticConstMacro(OutputImageDimension, unsigned int,
                      TOutputImage::ImageDimension);

  /** Inherit types from Superclass. */
  typedef typename Superclass::InputImageType InputImageType;
  typedef typename Superclass::OutputImageType OutputImageType;
  typedef typename Superclass::InputImagePointer InputImagePointer;
  typedef typename Superclass::OutputImagePointer OutputImagePointer;
  typedef typename Superclass::InputImageConstPointer InputImageConstPointer;

  /** Set the number of multi-resolution levels. The matrix containing the
   * schedule will be resized accordingly.  The schedule is populated with
   * default values.  At the coarset (0) level, the shrink factors are set
   * 2^(nlevel - 1) for all dimension. These shrink factors are halved for
   * subsequent levels.  The number of levels is clamped to a minimum value
   * of 1.  All shrink factors are also clamped to a minimum value of 1. */
  void SetNumberOfLevels(unsigned int num);

  /** Get the number of multi-resolution levels. */
  itkGetMacro(NumberOfLevels, unsigned int);

  /** Set a multi-resolution schedule.  The input schedule must have only
   * ImageDimension number of columns and NumberOfLevels number of rows.  For
   * each dimension, the shrink factor must be non-increasing with respect to
   * subsequent levels. This function will clamp shrink factors to satisify
   * this condition.  All shrink factors less than one will also be clamped
   * to the value of 1. */
  void SetSchedule( const ScheduleType& schedule );

  /** Get the multi-resolution schedule. */
  itkGetConstReferenceMacro(Schedule, ScheduleType);

  /** Set the starting shrink factor for the coarset (0) resolution
   * level. The schedule is then populated with defaults values obtained by
   * halving the factors at the previous level.  All shrink factors are
   * clamped to a minimum value of 1. */
  void SetStartingShrinkFactors( unsigned int factor );
  void SetStartingShrinkFactors( unsigned int* factors );

  /** Get the starting shrink factors */
  const unsigned int * GetStartingShrinkFactors() const;

  /** Test if the schedule is downward divisible. This method returns true if
   * at every level, the shrink factors are divisble by the shrink factors at
   * the next level. */
  static bool IsScheduleDownwardDivisible( const ScheduleType& schedule );

  /** MultiResolutionPyramidImageFilter produces images which are of
   * different resolution and different pixel spacing than its input image.
   * As such, MultiResolutionPyramidImageFilter needs to provide an
   * implementation for GenerateOutputInformation() in order to inform the
   * pipeline execution model.  The original documentation of this method is
   * below.  \sa ProcessObject::GenerateOutputInformaton() */
  virtual void GenerateOutputInformation();

  /** Given one output whose requested region has been set, this method sets
   * the requested region for the remaining output images.  The original
   * documentation of this method is below.  \sa
   * ProcessObject::GenerateOutputRequestedRegion(); */
  virtual void GenerateOutputRequestedRegion(DataObject *output);

  /** MultiResolutionPyramidImageFilter requires a larger input requested
   * region than the output requested regions to accomdate the shrinkage and
   * smoothing operations. As such, MultiResolutionPyramidImageFilter needs
   * to provide an implementation for GenerateInputRequestedRegion().  The
   * original documentation of this method is below.  \sa
   * ProcessObject::GenerateInputRequestedRegion() */
  virtual void GenerateInputRequestedRegion();

  itkSetMacro(MaximumError,double);
  itkGetConstReferenceMacro(MaximumError,double);

#ifdef ITK_USE_CONCEPT_CHECKING
  /** Begin concept checking */
  itkConceptMacro(SameDimensionCheck,
    (Concept::SameDimension<ImageDimension, OutputImageDimension>));
  itkConceptMacro(OutputHasNumericTraitsCheck,
    (Concept::HasNumericTraits<typename TOutputImage::PixelType>));
  /** End concept checking */
#endif
protected:
  MultiResolutionPyramidImageFilter();
  ~MultiResolutionPyramidImageFilter() {};
  void PrintSelf(std::ostream&os, Indent indent) const;

  /** Generate the output data. */
  void GenerateData();

  double          m_MaximumError; 
  unsigned int    m_NumberOfLevels;
  ScheduleType    m_Schedule;

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


} // namespace itk

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

#endif


