/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/

#ifndef __itkHuangThresholdCalculator_h
#define __itkHuangThresholdCalculator_h

#include "itkHistogramThresholdCalculator.h"

namespace itk
{

/** \class HuangThresholdCalculator
 * \brief Computes the Huang's threshold for an image.
 *
 * This calculator computes the Huang's fuzzy threshold which separates an image
 * into foreground and background components. Uses Shannon's entropy
 * function (one can also use Yager's entropy function)
 * Huang L.-K. and Wang M.-J.J. (1995) "Image Thresholding by Minimizing
 * the Measures of Fuzziness" Pattern Recognition, 28(1): 41-51
 * Reimplemented (to handle 16-bit efficiently) by Johannes Schindelin Jan 31, 2011
 *
 * This class is templated over the input histogram type.
 * \warning This calculator assumes that the input histogram has only one dimension.
 *
 * \author Richard Beare. Department of Medicine, Monash University,
 * Melbourne, Australia.
 * \author Gaetan Lehmann. Biologie du Developpement et de la Reproduction, INRA de Jouy-en-Josas, France.
 *
 * This implementation was taken from the Insight Journal paper:
 * http://hdl.handle.net/10380/3279  or
 * http://www.insight-journal.org/browse/publication/811
 *
 * \ingroup Operators
 * \ingroup ITKThresholding
 */
template <typename THistogram, typename TOutput=double>
class HuangThresholdCalculator : public HistogramThresholdCalculator<THistogram, TOutput>
{
public:
  /** Standard class typedefs. */
  typedef HuangThresholdCalculator        Self;
  typedef Object                          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(HuangThresholdCalculator, Object);

  /** Type definition for the input image. */
  typedef THistogram  HistogramType;
  typedef TOutput     OutputType;

protected:
  HuangThresholdCalculator() { m_FirstBin = 0; m_LastBin = 0; m_Size = 0; }
  virtual ~HuangThresholdCalculator() {}
  void GenerateData(void);

  typedef typename HistogramType::TotalAbsoluteFrequencyType  TotalAbsoluteFrequencyType;
  typedef typename HistogramType::AbsoluteFrequencyType       AbsoluteFrequencyType;
  typedef typename HistogramType::InstanceIdentifier          InstanceIdentifier;
  typedef typename HistogramType::SizeValueType               SizeValueType;
  typedef typename HistogramType::MeasurementType             MeasurementType;

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

  InstanceIdentifier  m_FirstBin;
  InstanceIdentifier  m_LastBin;
  SizeValueType       m_Size;

};

} // end namespace itk


#ifndef ITK_MANUAL_INSTANTIATION
#include "itkHuangThresholdCalculator.hxx"
#endif

#endif
