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

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkShrinkImageFilter.h,v $
  Language:  C++
  Date:      $Date: 2006/03/22 16:26:45 $
  Version:   $Revision: 1.42 $

  Copyright (c) Insight Software Consortium. All rights reserved.
  See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.

  Portions of this code are covered under the VTK copyright.
  See VTKCopyright.txt or http://www.kitware.com/VTKCopyright.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 __itkShrinkImageFilter_h
#define __itkShrinkImageFilter_h

#include "itkImageToImageFilter.h"

namespace itk
{

/** \class ShrinkImageFilter
 * \brief Reduce the size of an image by an integer factor in each
 * dimension.
 *
 * ShrinkImageFilter reduces the size of an image by an integer factor
 * in each dimension. The algorithm implemented is a simple subsample. 
 * The output image size in each dimension is given by:
 *
 * outputSize[j] = max( vcl_floor(inputSize[j]/shrinkFactor[j]), 1 ); 
 *
 * Since this filter produces an image which is a different resolution 
 * and with different pixel spacing than its input image, 
 * it needs to override several of the methods defined
 * in ProcessObject in order to properly manage the pipeline execution model.
 * In particular, this filter overrides
 * ProcessObject::GenerateInputRequestedRegion() and
 * ProcessObject::GenerateOutputInformation().
 *
 * This filter is implemented as a multithreaded filter.  It provides a 
 * ThreadedGenerateData() method for its implementation.
 * 
 * \ingroup GeometricTransforms
 */
template <class TInputImage, class TOutputImage>
class ITK_EXPORT ShrinkImageFilter:
    public ImageToImageFilter<TInputImage,TOutputImage>
{
public:
  /** Standard class typedefs. */
  typedef ShrinkImageFilter         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(ShrinkImageFilter, ImageToImageFilter);

  /** Typedef to images */
  typedef TOutputImage                                OutputImageType;
  typedef TInputImage                                 InputImageType;
  typedef typename OutputImageType::Pointer           OutputImagePointer;
  typedef typename InputImageType::Pointer            InputImagePointer;
  typedef typename InputImageType::ConstPointer       InputImageConstPointer;

  /** Typedef to describe the output image region type. */
  typedef typename TOutputImage::RegionType OutputImageRegionType;

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

  /** Set the shrink factors. Values are clamped to 
   * a minimum value of 1. Default is 1 for all dimensions. */
  void SetShrinkFactors( unsigned int factors[] );
  void SetShrinkFactors( unsigned int factor );
  void SetShrinkFactor( unsigned int i, unsigned int factor )
  {
    m_ShrinkFactors[i] = factor;
  }
  
  /** Get the shrink factors. */
  const unsigned int * GetShrinkFactors() const
  { return m_ShrinkFactors; }
                 
  /** ShrinkImageFilter produces an image which is a different
   * resolution and with a different pixel spacing than its input
   * image.  As such, ShrinkImageFilter 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();

  /** ShrinkImageFilter needs a larger input requested region than the output
   * requested region.  As such, ShrinkImageFilter needs to provide an
   * implementation for GenerateInputRequestedRegion() in order to inform the
   * pipeline execution model.
   * \sa ProcessObject::GenerateInputRequestedRegion() */
  virtual void GenerateInputRequestedRegion();
  virtual void EnlargeOutputRequestedRegion(DataObject *output); 

#ifdef ITK_USE_CONCEPT_CHECKING
  /** Begin concept checking */
  itkConceptMacro(InputConvertibleToOutputCheck,
    (Concept::Convertible<typename TInputImage::PixelType, typename TOutputImage::PixelType>));
  itkConceptMacro(SameDimensionCheck,
    (Concept::SameDimension<ImageDimension, OutputImageDimension>));
  /** End concept checking */
#endif

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

  /** ShrinkImageFilter can be implemented as a multithreaded filter.
   * Therefore, this implementation provides a ThreadedGenerateData() routine
   * which is called for each processing thread. The output image data is
   * allocated automatically by the superclass prior to calling
   * ThreadedGenerateData().  ThreadedGenerateData can only write to the
   * portion of the output image specified by the parameter
   * "outputRegionForThread"
   *
   * \sa ImageToImageFilter::ThreadedGenerateData(),
   *     ImageToImageFilter::GenerateData() */
  void ThreadedGenerateData(const OutputImageRegionType& outputRegionForThread,
                            int threadId );

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

  unsigned int m_ShrinkFactors[ImageDimension];
};

  
} // end namespace itk
  
#ifndef ITK_MANUAL_INSTANTIATION
#include "itkShrinkImageFilter.txx"
#endif
  
#endif
