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

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkGrayscaleFunctionErodeImageFilter.txx,v $
  Language:  C++
  Date:      $Date: 2004/04/30 21:02:04 $
  Version:   $Revision: 1.13 $

  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 __itkGrayscaleFunctionErodeImage_txx
#define __itkGrayscaleFunctionErodeImage_txx

#include "itkGrayscaleFunctionErodeImageFilter.h"

namespace itk {

template<class TInputImage, class TOutputImage, class TKernel>
GrayscaleFunctionErodeImageFilter<TInputImage, TOutputImage, TKernel>
::GrayscaleFunctionErodeImageFilter()
{
  m_ErodeBoundaryCondition.SetConstant( NumericTraits<PixelType>::max() );
  this->OverrideBoundaryCondition( &m_ErodeBoundaryCondition );
}

template<class TInputImage, class TOutputImage, class TKernel>
typename GrayscaleFunctionErodeImageFilter<TInputImage, TOutputImage, TKernel>::PixelType
GrayscaleFunctionErodeImageFilter<TInputImage, TOutputImage, TKernel>
::Evaluate(const NeighborhoodIteratorType &nit,
           const KernelIteratorType kernelBegin,
           const KernelIteratorType kernelEnd)
{
  unsigned int i;
  PixelType min = NumericTraits<PixelType>::max();
  PixelType temp;
  
  KernelIteratorType kernel_it;

  for (i=0, kernel_it=kernelBegin; kernel_it<kernelEnd; ++kernel_it, ++i)
    {
    // if structuring element is positive, use the pixel under that element
    // in the image minus the structuring element value
    if (*kernel_it > 0)
      {
      // subtract the structuring element value to the pixel value,
      // note we use GetPixel() on SmartNeighborhoodIterator to respect
      // boundary condition
      temp = nit.GetPixel(i) - (PixelType) *kernel_it;

      if (temp < min)
        min = temp ;
      }
    }
  
  return min; 
} 
  
}// end namespace itk
#endif
