text: /*
   * Copyright (C) 2005-2020 Centre National d'Etudes Spatiales (CNES)
   *
   * This file is part of Orfeo Toolbox
   *
   *     https://www.orfeo-toolbox.org/
   *
   * 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
   *
   * 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 otbVarianceImageFilter_h
  #define otbVarianceImageFilter_h
  
  #include "itkImageToImageFilter.h"
  #include "itkImage.h"
  #include "itkNumericTraits.h"
  
  namespace otb
  {
  /** \class VarianceImageFilter
   * \brief Applies an averaging filter to an image
   *
   * Computes an image where a given pixel is the value over the standard 8, 26, etc. connected
   * neighborhood. This calculation uses a ZeroFluxNeumannBoundaryCondition.
   *
   *
   * \sa Image
   * \sa Neighborhood
   * \sa NeighborhoodOperator
   * \sa NeighborhoodIterator
   *
   * \ingroup IntensityImageFilters
   *
   * \ingroup OTBStatistics
   */
  template <class TInputImage, class TOutputImage>
  class ITK_EXPORT VarianceImageFilter : public itk::ImageToImageFilter<TInputImage, TOutputImage>
  {
  public:
    /** Extract dimension from input and output image. */
    itkStaticConstMacro(InputImageDimension, unsigned int, TInputImage::ImageDimension);
    itkStaticConstMacro(OutputImageDimension, unsigned int, TOutputImage::ImageDimension);
  
    /** Convenient typedefs for simplifying declarations. */
    typedef TInputImage  InputImageType;
    typedef TOutputImage OutputImageType;
  
    /** Standard class typedefs. */
    typedef VarianceImageFilter Self;
    typedef itk::ImageToImageFilter<InputImageType, OutputImageType> Superclass;
    typedef itk::SmartPointer<Self>       Pointer;
    typedef itk::SmartPointer<const Self> ConstPointer;
  
    /** Method for creation through the object factory. */
    itkNewMacro(Self);
  
    /** Run-time type information (and related methods). */
    itkTypeMacro(VarianceImageFilter, ImageToImageFilter);
  
    /** Image typedef support. */
    typedef typename InputImageType::PixelType                    InputPixelType;
    typedef typename OutputImageType::PixelType                   OutputPixelType;
    typedef typename itk::NumericTraits<InputPixelType>::RealType InputRealType;
  
    typedef typename InputImageType::RegionType  InputImageRegionType;
    typedef typename OutputImageType::RegionType OutputImageRegionType;
  
    typedef typename InputImageType::SizeType InputSizeType;
  
    /** Set the radius of the neighborhood used to compute the mean. */
    itkSetMacro(Radius, InputSizeType);
  
    /** Get the radius of the neighborhood used to compute the mean */
    itkGetConstReferenceMacro(Radius, InputSizeType);
  
    /** VarianceImageFilter needs a larger input requested region than
     * the output requested region.  As such, VarianceImageFilter needs
     * to provide an implementation for GenerateInputRequestedRegion()
     * in order to inform the pipeline execution model.
     *
     * \sa ImageToImageFilter::GenerateInputRequestedRegion() */
    void GenerateInputRequestedRegion() override;
  
  #ifdef ITK_USE_CONCEPT_CHECKING
    /** Begin concept checking */
    itkConceptMacro(InputHasNumericTraitsCheck, (itk::Concept::HasNumericTraits<InputPixelType>));
  /** End concept checking */
  #endif
  
  protected:
    VarianceImageFilter();
    ~VarianceImageFilter() override
    {
    }
    void PrintSelf(std::ostream& os, itk::Indent indent) const override;
  
    /** VarianceImageFilter 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, itk::ThreadIdType threadId) override;
  
  private:
    VarianceImageFilter(const Self&) = delete;
    void operator=(const Self&) = delete;
  
    InputSizeType m_Radius;
  };
  
  } // end namespace otb
  
  #ifndef OTB_MANUAL_INSTANTIATION
  #include "otbVarianceImageFilter.hxx"
  #endif
  
  #endif
  