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Article 9 — Appendix A.1

Gaussian filter, or Gaussian blur source code

Category. Digital signal and image processing (DSP and DIP) software development.

Description. Separable Gaussian filter, or Gaussian blur C++ source code — header file.

Reference. Separable Gaussian filter, or Gaussian blur C++ source code — implementation file.

Download Gaussian filter, or Gaussian blur C++ source code (zip, 4 Kb)

gaussianblur.h

//   gaussianblur.h - declaration of template class
//   of 1D and 2D gaussian blur or filter
//
//   The code is property of LIBROW
//   You can use it on your own
//   When utilizing credit LIBROW site

#ifndef _GAUSSIANBLUR_H_
#define _GAUSSIANBLUR_H_

template <class T = double> class TGaussianBlur
{
public:
   //   1D GAUSSIAN BLUR
   //     pSignal - input signal;
   //     pResult - output signal, NULL for inplace processing
   //     N       - length of the signal
   //     W       - window size, odd positive number
   bool Filter(T *pSignal, T *pResult, unsigned int N, unsigned int W) const;

   //   2D GAUSSIAN BLUR
   //     pImage  - input image
   //     pResult - output image, NULL for inplace processing
   //     N       - width of the image
   //     M       - height of the image
   //     W       - window size, odd positive number
   bool Filter(T *pImage, T *pResult,
      unsigned int N, unsigned int M, unsigned int W) const;

protected:
   //   Internal auxiliary structure - data array size descriptor
   struct CSize
   {
      unsigned int x;   //   Array width
      unsigned int y;   //   Array height

      //   Default constructor
      CSize(): x(0), y(0) {}
      //   Constructor with initialization
      CSize(unsigned int _x, unsigned int _y): x(_x), y(_y) {}

      //   Initialization
      void Set(unsigned int _x, unsigned int _y) { x = _x; y = _y; }
      //   Area
      unsigned int Area() const { return x * y; }
   };

   //   Internal auxiliary structure - array descriptor
   struct CArray
   {
      CSize Size;   //   Array size
      T *Buffer;    //   Element buffer

      //   Default constructor
      CArray(): Buffer(NULL) {}
      //   Constructors with initialization
      CArray(T *_Buffer, const CSize &_Size): Buffer(_Buffer), Size(_Size) {}
      CArray(T *_Buffer, unsigned int _N): Buffer(_Buffer), Size(_N, 1) {}
   };

   //   Internal auxiliary structure - filter window descriptor
   struct CWindow
   {
      T *Weights;   //   Window weights
      unsigned int Size;   //   Window size

      //   Default constructor
      CWindow(): Weights(NULL), Size(0), Correction(.5 - double(T(.5))) {}
      //   Destructor
      ~CWindow() { if (Weights) delete[] Weights; }

      //   Filter window creation
      bool Create(unsigned int _Size);

      //   FILTER WINDOW APPLICATION
      //     _Element - start element in signal/image
      T Apply(const T *_Element) const
      {
         //   Apply filter - calculate weighted mean
         double Sum = 0.;
         const double *WeightIter = Weights;
         const T *ElIter = _Element;
         const double *const End = Weights + Size;
         while (WeightIter < End)
            Sum += *(WeightIter++) * double(*(ElIter++));
         return T(Sum + Correction);
      }

   protected:
      const double Correction;   //   Result correction
   };

   //   Internal auxiliary functions - check input data consistency
   bool Consistent(const T *_Image, const CSize &_Size, unsigned int _W) const
   {
      return  _Image && _Size.x && _Size.y && _W &&
         _Size.x > (_W >> 1) && _Size.y > (_W >> 1) && _W & 1;
   }
   bool Consistent(const T *_Signal, unsigned int _N, unsigned int _W) const
   {
      return  _Signal && _N && _W && _N > (_W >> 1) && _W & 1;
   }
};

//   Include implementation file
#include "gaussianblur.cpp"

#endif