text: /*=========================================================================
   *
   *  Copyright NumFOCUS
   *
   *  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 itkLaplacianRecursiveGaussianImageFilter_h
  #define itkLaplacianRecursiveGaussianImageFilter_h
  
  #include "itkRecursiveGaussianImageFilter.h"
  #include "itkImage.h"
  #include "itkCommand.h"
  
  namespace itk
  {
  /**
   *\class LaplacianRecursiveGaussianImageFilter
   * \brief Computes the Laplacian of Gaussian (LoG) of an image.
   *
   * Computes the Laplacian of Gaussian (LoG) of an image by convolution
   * with the second derivative of a Gaussian.
   * This filter is implemented using the recursive gaussian filters.
   *
   * \ingroup GradientFilters
   * \ingroup MultiThreaded
   * \ingroup ITKImageFeature
   *
   * \spihnx
   * \sphinxexample{Filtering/ImageFeature/ComputeLaplacian,Compute Laplacian}
   * \endsphinx
   */
  template <typename TInputImage, typename TOutputImage = TInputImage>
  class ITK_TEMPLATE_EXPORT LaplacianRecursiveGaussianImageFilter : public ImageToImageFilter<TInputImage, TOutputImage>
  {
  public:
    ITK_DISALLOW_COPY_AND_ASSIGN(LaplacianRecursiveGaussianImageFilter);
  
    /** Standard class type aliases. */
    using Self = LaplacianRecursiveGaussianImageFilter;
    using Superclass = ImageToImageFilter<TInputImage, TOutputImage>;
    using Pointer = SmartPointer<Self>;
    using ConstPointer = SmartPointer<const Self>;
  
    /** Pixel Type of the input image */
    using InputImageType = TInputImage;
    using PixelType = typename InputImageType::PixelType;
  
    /** Image dimension. */
    static constexpr unsigned int ImageDimension = TInputImage::ImageDimension;
  
    static constexpr unsigned int NumberOfSmoothingFilters = ImageDimension - 1;
  
    using RealType = typename NumericTraits<PixelType>::RealType;
  
    /** Define the image type for internal computations.
        RealType is usually 'double' in NumericTraits.
        Here we prefer float in order to save memory.  */
    using InternalRealType = float;
    using RealImageType = Image<InternalRealType, Self::ImageDimension>;
  
    /**  Smoothing filter type */
    using GaussianFilterType = RecursiveGaussianImageFilter<RealImageType, RealImageType>;
  
    /**  Derivative filter type, it will be the first in the pipeline  */
    using DerivativeFilterType = RecursiveGaussianImageFilter<InputImageType, RealImageType>;
  
    /**  Pointer to a gaussian filter.  */
    using GaussianFilterPointer = typename GaussianFilterType::Pointer;
  
    /**  Pointer to a derivative filter.  */
    using DerivativeFilterPointer = typename DerivativeFilterType::Pointer;
  
    /**  Pointer to the Output Image */
    using OutputImagePointer = typename TOutputImage::Pointer;
  
    /** Type of the output Image */
    using OutputImageType = TOutputImage;
    using OutputPixelType = typename OutputImageType::PixelType;
  
  
    /**  Command for observing progress of internal pipeline filters */
    using CommandType = MemberCommand<Self>;
    using CommandPointer = typename CommandType::Pointer;
  
    /** Method for creation through the object factory. */
    itkNewMacro(Self);
  
    /** Runtime information support. */
    itkTypeMacro(LaplacianRecursiveGaussianImageFilter, ImageToImageFilter);
  
    /** Set Sigma value. Sigma is measured in the units of image spacing. */
    void
    SetSigma(RealType sigma);
    RealType
    GetSigma() const;
  
    /** Define which normalization factor will be used for the Gaussian
     *  \sa  RecursiveGaussianImageFilter::SetNormalizeAcrossScale
     */
    void
    SetNormalizeAcrossScale(bool normalizeInScaleSpace);
    itkGetConstMacro(NormalizeAcrossScale, bool);
  
  protected:
    LaplacianRecursiveGaussianImageFilter();
    ~LaplacianRecursiveGaussianImageFilter() override = default;
    void
    PrintSelf(std::ostream & os, Indent indent) const override;
  
    /** Generate Data */
    void
    GenerateData() override;
  
    // Override since the filter produces the entire dataset
    void
    EnlargeOutputRequestedRegion(DataObject * output) override;
  
  private:
    GaussianFilterPointer   m_SmoothingFilters[NumberOfSmoothingFilters];
    DerivativeFilterPointer m_DerivativeFilter;
  
    /** Normalize the image across scale space */
    bool m_NormalizeAcrossScale;
  };
  } // end namespace itk
  
  #ifndef ITK_MANUAL_INSTANTIATION
  #  include "itkLaplacianRecursiveGaussianImageFilter.hxx"
  #endif
  
  #endif
  