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  #ifndef OPENCV_STITCHING_BLENDERS_HPP
  #define OPENCV_STITCHING_BLENDERS_HPP
  
  #if defined(NO)
  #  warning Detected Apple 'NO' macro definition, it can cause build conflicts. Please, include this header before any Apple headers.
  #endif
  
  #include "opencv2/core.hpp"
  
  namespace cv {
  namespace detail {
  
  //! @addtogroup stitching_blend
  //! @{
  
  /** @brief Base class for all blenders.
  
  Simple blender which puts one image over another
  */
  class CV_EXPORTS Blender
  {
  public:
      virtual ~Blender() {}
  
      enum { CNO, FEATHER, MULTI_BAND };
      static Ptr<Blender> createDefault(int type, bool try_gpu = false);
  
      /** @brief Prepares the blender for blending.
  
      @param corners Source images top-left corners
      @param sizes Source image sizes
       */
      void prepare(const std::vector<Point> &corners, const std::vector<Size> &sizes);
      /** @overload */
      virtual void prepare(Rect dst_roi);
      /** @brief Processes the image.
  
      @param img Source image
      @param mask Source image mask
      @param tl Source image top-left corners
       */
      virtual void feed(InputArray img, InputArray mask, Point tl);
      /** @brief Blends and returns the final pano.
  
      @param dst Final pano
      @param dst_mask Final pano mask
       */
      virtual void blend(InputOutputArray dst, InputOutputArray dst_mask);
  
  protected:
      UMat dst_, dst_mask_;
      Rect dst_roi_;
  };
  
  /** @brief Simple blender which mixes images at its borders.
   */
  class CV_EXPORTS FeatherBlender : public Blender
  {
  public:
      FeatherBlender(float sharpness = 0.02f);
  
      float sharpness() const { return sharpness_; }
      void setSharpness(float val) { sharpness_ = val; }
  
      void prepare(Rect dst_roi);
      void feed(InputArray img, InputArray mask, Point tl);
      void blend(InputOutputArray dst, InputOutputArray dst_mask);
  
      //! Creates weight maps for fixed set of source images by their masks and top-left corners.
      //! Final image can be obtained by simple weighting of the source images.
      Rect createWeightMaps(const std::vector<UMat> &masks, const std::vector<Point> &corners,
                            std::vector<UMat> &weight_maps);
  
  private:
      float sharpness_;
      UMat weight_map_;
      UMat dst_weight_map_;
  };
  
  inline FeatherBlender::FeatherBlender(float _sharpness) { setSharpness(_sharpness); }
  
  /** @brief Blender which uses multi-band blending algorithm (see @cite BA83).
   */
  class CV_EXPORTS MultiBandBlender : public Blender
  {
  public:
      MultiBandBlender(int try_gpu = false, int num_bands = 5, int weight_type = CV_32F);
  
      int numBands() const { return actual_num_bands_; }
      void setNumBands(int val) { actual_num_bands_ = val; }
  
      void prepare(Rect dst_roi);
      void feed(InputArray img, InputArray mask, Point tl);
      void blend(InputOutputArray dst, InputOutputArray dst_mask);
  
  private:
      int actual_num_bands_, num_bands_;
      std::vector<UMat> dst_pyr_laplace_;
      std::vector<UMat> dst_band_weights_;
      Rect dst_roi_final_;
      bool can_use_gpu_;
      int weight_type_; //CV_32F or CV_16S
  };
  
  
  //////////////////////////////////////////////////////////////////////////////
  // Auxiliary functions
  
  void CV_EXPORTS normalizeUsingWeightMap(InputArray weight, InputOutputArray src);
  
  void CV_EXPORTS createWeightMap(InputArray mask, float sharpness, InputOutputArray weight);
  
  void CV_EXPORTS createLaplacePyr(InputArray img, int num_levels, std::vector<UMat>& pyr);
  void CV_EXPORTS createLaplacePyrGpu(InputArray img, int num_levels, std::vector<UMat>& pyr);
  
  // Restores source image
  void CV_EXPORTS restoreImageFromLaplacePyr(std::vector<UMat>& pyr);
  void CV_EXPORTS restoreImageFromLaplacePyrGpu(std::vector<UMat>& pyr);
  
  //! @}
  
  } // namespace detail
  } // namespace cv
  
  #endif // OPENCV_STITCHING_BLENDERS_HPP
  