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/*=========================================================================
*
* Copyright Insight Software Consortium
*
* 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 itkUnsharpMaskLevelSetImageFilter_h
#define itkUnsharpMaskLevelSetImageFilter_h
#include "itkSparseFieldFourthOrderLevelSetImageFilter.h"
namespace itk
{
/**
* \class UnsharpMaskLevelSetImageFilter
*
* \brief This class implements a detail enhancing filter by making use of the
* 4th-order level set isotropic diffusion (smoothing) PDE.
*
* \par INPUT and OUTPUT
* This is a volume to volume filter; however, it is meant to process (smooth)
* surfaces. The input surface is an isosurface of the input volume. The
* isosurface value to be processed can be set by calling SetIsoSurfaceValue
* (default is 0). The output surface is the 0-isosurface of the output volume,
* regardless of the input isosurface value. To visualize the input/output
* surfaces to this filter a mesh extraction method such as marching cubes can
* be used.
*
* \par
* This filter is an example of how the 4th order level set PDE framework can
* be used for general purpose surface processing. It is motivated by unsharp
* masking from image processing which is a way of enhancing detail. This
* filter acts much like the IsotropicFourthOrderLevelSetImageFilter because it
* first smoothes the normal vectors via isotropic diffusion. However, as a
* post-processing step we extrapolate from the original normals in the
* direction opposite to the new processes normals. By refiting the surface to
* these extrapolated vectors we achieve detail enhancement. This process is
* not the same as running the isotropic diffusion process in reverse.
*
* \par IMPORTANT
* Because this filters enhances details on the surface, it will also amplify
* noise! This filter is provided only as an example of graphics oriented
* post-processing. Do not use it on noisy data.
*
* \par PARAMETERS
* As mentioned before, the IsoSurfaceValue parameter chooses which isosurface
* of the input to process. The MaxFilterIterations parameter determine the
* number of iterations for which this filter will run. Since, this filter
* enhances detail AND noise MaxFilterIterations above a couple of hundred are
* unreasonable. Finally NormalProcessUnsharpWeight controls the amount of
* extrapolation (or equivalently the amount of detail enhancement). This value
* should be in the range [0.1,1] for reasonable results.
* \ingroup ITKLevelSets
*/
template< typename TInputImage, typename TOutputImage >
class ITK_TEMPLATE_EXPORT UnsharpMaskLevelSetImageFilter:
public SparseFieldFourthOrderLevelSetImageFilter< TInputImage, TOutputImage >
{
public:
/** Standard class typedefs */
typedef UnsharpMaskLevelSetImageFilter Self;
typedef SparseFieldFourthOrderLevelSetImageFilter< TInputImage, TOutputImage > Superclass;
typedef SmartPointer< Self > Pointer;
typedef SmartPointer< const Self > ConstPointer;
/** Run-time type information (and related methods) */
itkTypeMacro(UnsharpMaskLevelSetImageFilter,
SparseFieldFourthOrderLevelSetImageFilter);
/** Standard new macro */
itkNewMacro(Self);
/** The sparse image type used in LevelSetFunctionWithRefitTerm */
typedef typename Superclass::SparseImageType SparseImageType;
/** The level set function class with a refit term that forces the curvature
of the moving front to match a prescribed curvature image. */
typedef LevelSetFunctionWithRefitTerm< TOutputImage, SparseImageType > FunctionType;
/** The radius type for the neighborhoods. */
typedef typename FunctionType::RadiusType RadiusType;
itkGetConstMacro(MaxFilterIteration, unsigned int);
itkSetMacro(MaxFilterIteration, unsigned int);
protected:
UnsharpMaskLevelSetImageFilter();
~UnsharpMaskLevelSetImageFilter() ITK_OVERRIDE {}
virtual void PrintSelf(std::ostream & os, Indent indent) const ITK_OVERRIDE;
/** The LevelSetFunctionWithRefitTerm object. */
typename FunctionType::Pointer m_Function;
/** The number of iterations for which this filter will run. */
unsigned int m_MaxFilterIteration;
/** This filter halts when the iteration count reaches the specified count. */
virtual bool Halt() ITK_OVERRIDE
{
if ( this->GetElapsedIterations() == m_MaxFilterIteration )
{
return true;
}
else
{
return false;
}
}
private:
ITK_DISALLOW_COPY_AND_ASSIGN(UnsharpMaskLevelSetImageFilter);
};
} // end namespace itk
#ifndef ITK_MANUAL_INSTANTIATION
#include "itkUnsharpMaskLevelSetImageFilter.hxx"
#endif
#endif
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