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/*========================================================================= |
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Program: Insight Segmentation & Registration Toolkit |
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Module: $RCSfile: itkGaussianOperator.h.html,v $ |
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Language: C++ |
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Date: $Date: 2006/01/17 19:15:36 $ |
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Version: $Revision: 1.4 $ |
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Copyright (c) Insight Software Consortium. All rights reserved. |
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See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details. |
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This software is distributed WITHOUT ANY WARRANTY; without even |
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the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR |
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PURPOSE. See the above copyright notices for more information. |
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=========================================================================*/ |
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#ifndef __itkGaussianOperator_h |
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#define __itkGaussianOperator_h |
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#include "itkNeighborhoodOperator.h" |
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#include <math.h> |
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namespace itk { |
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/** |
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* \class GaussianOperator |
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* \brief A NeighborhoodOperator whose coefficients are a one |
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* dimensional, discrete Gaussian kernel. |
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* |
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* GaussianOperator can be used to perform Gaussian blurring |
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* by taking its inner product with to a Neighborhood |
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* (NeighborhooIterator) that is swept across an image region. |
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* It is a directional operator. N successive applications |
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* oriented along each dimensional direction will effect separable, |
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* efficient, N-D Gaussian blurring of an image region. |
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* |
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* GaussianOperator takes two parameters: |
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* (1) The floating-point variance of the desired Gaussian function. |
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* (2) The "maximum error" allowed in the discrete Gaussian |
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* function. "Maximum errror" is defined as the difference between the area |
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* under the discrete Gaussian curve and the area under the continuous |
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* Gaussian. Maximum error affects the Gaussian operator size. Care should |
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* be taken not to make this value too small relative to the variance |
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* lest the operator size become unreasonably large. |
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* |
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* References: |
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* The Gaussian kernel contained in this operator was described |
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* by Tony Lindeberg (Discrete Scale-Space Theory and the Scale-Space |
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* Primal Sketch. Dissertation. Royal Institute of Technology, Stockholm, |
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* Sweden. May 1991.). |
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* |
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* \sa NeighborhoodOperator |
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* \sa NeighborhoodIterator |
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* \sa Neighborhood |
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* |
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* \ingroup Operators |
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*/ |
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template<class TPixel,unsigned int VDimension=2, |
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class TAllocator = NeighborhoodAllocator<TPixel> > |
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class ITK_EXPORT GaussianOperator |
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**: public NeighborhoodOperator<TPixel, VDimension, TAllocator> |
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{ |
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public: |
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/** Standard class typedefs. */ |
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typedef GaussianOperator Self; |
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TDA |
typedef NeighborhoodOperator<TPixel, VDimension, TAllocator> Superclass; |
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/** Constructor. */ |
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GaussianOperator() : m_Variance(1), m_MaximumError(.01), m_MaximumKernelWidth(30) { } |
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/** Copy constructor */ |
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GaussianOperator(const Self &other) |
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****: NeighborhoodOperator<TPixel, VDimension, TAllocator>(other) |
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**{ |
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m_Variance = other.m_Variance; |
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m_MaximumError = other.m_MaximumError; |
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m_MaximumKernelWidth = other.m_MaximumKernelWidth; |
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**} |
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/** Assignment operator */ |
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Self &operator=(const Self &other) |
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**{ |
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Superclass::operator=(other); |
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m_Variance = other.m_Variance; |
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m_MaximumError = other.m_MaximumError; |
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m_MaximumKernelWidth = other.m_MaximumKernelWidth; |
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return *this; |
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**} |
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/** Sets the desired variance of the Gaussian kernel. */ |
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void SetVariance(const double &variance) |
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**{ m_Variance = variance; } |
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/** Sets the desired maximum error of the gaussian approximation. Maximum |
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* error is the difference between the area under the discrete Gaussian curve |
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* and the area under the continuous Gaussian. Maximum error affects the |
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* Gaussian operator size. */ |
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void SetMaximumError(const double &max_error) |
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**{ |
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if (max_error >= 1 || max_error <= 0) |
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{ |
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throw ExceptionObject(__FILE__, __LINE__); |
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} |
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m_MaximumError = max_error; |
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} |
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/** Returns the variance of the Gaussian (scale) for the operator. */ |
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double GetVariance() |
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{ return m_Variance; } |
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/** Returns the maximum error of the gaussian approximation. Maximum error is |
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* the difference between the area under the discrete Gaussian curve and the |
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* area under the continuous Gaussian. Maximum error affects the Gaussian |
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* operator size. */ |
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double GetMaximumError() |
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{ return m_MaximumError; } |
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/** Sets a limit for growth of the kernel. Small maximum error values with |
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* large variances will yield very large kernel sizes. This value can be |
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* used to truncate a kernel in such instances. A warning will be given on |
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* truncation of the kernel. */ |
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void SetMaximumKernelWidth( unsigned int n ) |
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{ m_MaximumKernelWidth = n; } |
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/** Returns the maximum allowed kernel width. */ |
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unsigned int GetMaximumKernelWidth() const |
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{ return m_MaximumKernelWidth; } |
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/** Prints some debugging information. */ |
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virtual void PrintSelf(std::ostream &os, Indent i) const |
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{ |
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os << i << "GaussianOperator { this=" << this |
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<< ", m_Variance = " << m_Variance |
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<< ", m_MaximumError = " << m_MaximumError |
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<< "} " << std::endl; |
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Superclass::PrintSelf(os, i.GetNextIndent()); |
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} |
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protected: |
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typedef typename Superclass::CoefficientVector CoefficientVector; |
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/** Returns the value of the modified Bessel function I0(x) at a point x >= 0. */ |
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double ModifiedBesselI0(double); |
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/** Returns the value of the modified Bessel function I1(x) at a point x, |
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* x real. */ |
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double ModifiedBesselI1(double); |
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/** Returns the value of the modified Bessel function Ik(x) at a point x>=0, |
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* where k>=2. */ |
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double ModifiedBesselI(int, double); |
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/** Calculates operator coefficients. */ |
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CoefficientVector GenerateCoefficients(); |
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/** Arranges coefficients spatially in the memory buffer. */ |
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void Fill(const CoefficientVector& coeff) |
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**{ this->FillCenteredDirectional(coeff); } |
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private: |
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/** Desired variance of the discrete Gaussian function. */ |
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double m_Variance; |
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/** Difference between the areas under the curves of the continuous and |
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* discrete Gaussian functions. */ |
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double m_MaximumError; |
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/** Maximum kernel size allowed. This value is used to truncate a kernel |
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* that has grown too large. A warning is given when the specified maximum |
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* error causes the kernel to exceed this size. */ |
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unsigned int m_MaximumKernelWidth; |
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/** For compatibility with itkWarningMacro */ |
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const char *GetNameOfClass() |
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{ return "itkGaussianOperator"; } |
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}; |
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} // namespace itk |
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#ifndef ITK_MANUAL_INSTANTIATION |
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#include "itkGaussianOperator.txx" |
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#endif |
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#endif |
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