ITK  4.4.0
Insight Segmentation and Registration Toolkit
itkGaussianKernelFunction.h
Go to the documentation of this file.
1 /*=========================================================================
2  *
3  * Copyright Insight Software Consortium
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0.txt
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  *
17  *=========================================================================*/
18 #ifndef __itkGaussianKernelFunction_h
19 #define __itkGaussianKernelFunction_h
20 
21 #include "itkKernelFunctionBase.h"
22 #include "vnl/vnl_math.h"
23 #include <cmath>
24 
25 namespace itk
26 {
40 template< typename TRealValueType = double >
41 class ITK_EXPORT GaussianKernelFunction:public KernelFunctionBase<TRealValueType>
42 {
43 public:
48 
49  typedef typename Superclass::RealType RealType;
51  itkNewMacro(Self);
52 
55 
57  inline TRealValueType Evaluate(const TRealValueType & u) const
58  { return ( vcl_exp( static_cast< TRealValueType >(-0.5) * vnl_math_sqr(u) ) * m_Factor ); }
59 
60 protected:
61  GaussianKernelFunction(): m_Factor( NumericTraits< TRealValueType >::One / vcl_sqrt(static_cast< TRealValueType >(2.0 * vnl_math::pi )) ) {};
63  void PrintSelf(std::ostream & os, Indent indent) const
64  { Superclass::PrintSelf(os, indent); }
65 
66 private:
67  GaussianKernelFunction(const Self &); //purposely not implemented
68  void operator=(const Self &); //purposely not implemented
69 
70  const TRealValueType m_Factor;
71 };
72 } // end namespace itk
73 
74 #endif
75