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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 itkAntiAliasBinaryImageFilter_h
#define itkAntiAliasBinaryImageFilter_h
#include "itkSparseFieldLevelSetImageFilter.h"
#include "itkCurvatureFlowFunction.h"
namespace itk
{
/**
* \class AntiAliasBinaryImageFilter
* \brief A method for estimation of a surface from a binary volume.
*
* \par
* This filter implements a surface-fitting method for estimation of a
* surface from a binary volume. This process can be used to reduce aliasing
* artifacts which result in visualization of binary partitioned surfaces.
*
* \par
* The binary volume (filter input) is used as a set of constraints in an
* iterative relaxation process of an estimated ND surface. The surface is
* described implicitly as the zero level set of a volume \f$ \phi \f$ and
* allowed to deform under curvature flow. A set of constraints is imposed
* on this movement as follows:
*
* \par
* \f[ u_{i,j,k}^{n+1} = \left\{ \begin{array}{ll}
* \mbox{max} (u_{i,j,k}^{n} + \Delta t H_{i,j,k}^{n}, 0) & \mbox{$B_{i,j,k} = 1$} \\
* \mbox{min} (u_{i,j,k}^{n} + \Delta t H_{i,j,k}^{n}, 0) & \mbox{$B_{i,j,k} = -1$}
* \end{array}\right. \f]
*
* \par
* where \f$ u_{i,j,k}^{n} \f$ is the value of \f$ \phi \f$ at discrete index
* \f$ (i,j,k) \f$ and iteration \f$ n \f$, \f$ H \f$ is the gradient magnitude
* times mean curvature of \f$ \phi \f$, and \f$ B \f$ is the binary input
* volume, with 1 denoting an inside pixel and -1 denoting an outside pixel.
*
* \par NOTES
* This implementation uses a sparse field level set solver instead of the
* narrow band implementation described in the reference below, which may
* introduce some differences in how fast and how accurately (in terms of RMS
* error) the solution converges.
*
* \par REFERENCES
* Whitaker, Ross. "Reducing Aliasing Artifacts In Iso-Surfaces of Binary
* Volumes" IEEE Volume Visualization and Graphics Symposium, October 2000,
* pp.23-32.
*
* \par PARAMETERS
* The MaximumRMSChange parameter is used to determine when the solution has
* converged. A lower value will result in a tighter-fitting solution, but
* will require more computations. Too low a value could put the solver into
* an infinite loop. Values should always be less than 1.0. A value of 0.07
* is a good starting estimate.
*
* \par
* The MaximumIterations parameter can be used to halt the solution after a
* specified number of iterations.
*
* \par INPUT
* The input is an N-dimensional image of any type. It is assumed to be a
* binary image. The filter will use an isosurface value that is halfway
* between the min and max values in the image. A signed data type is *not*
* necessary for the input.
*
* \par OUTPUT
* The filter will output a level set image of real, signed values. The zero
* crossings of this (N-dimensional) image represent the position of the
* isosurface value of interest. Values outside the zero level set are
* negative and values inside the zero level set are positive values.
*
* \par IMPORTANT!
* The output image type you use to instantiate this filter should be a real
* valued scalar type. In other words: doubles or floats.
*
* \par USING THIS FILTER
* The filter is relatively straightforward to use. Tests and examples exist
* to illustrate. The important thing is to understand the input and output
* types so you can properly interperet your results.
*
* \par
* In the common case, the only parameter that will need to be set is the
* MaximumRMSChange parameter, which determines when the solver halts.
*
* \ingroup ITKAntiAlias
*
* \wiki
* \wikiexample{Smoothing/AntiAliasBinaryImageFilter,Anti alias a binary image}
* \endwiki
*/
template< typename TInputImage, typename TOutputImage >
class ITK_TEMPLATE_EXPORT AntiAliasBinaryImageFilter:
public SparseFieldLevelSetImageFilter< TInputImage, TOutputImage >
{
public:
/** Standard class typedefs */
typedef AntiAliasBinaryImageFilter Self;
typedef SparseFieldLevelSetImageFilter< TInputImage, TOutputImage > Superclass;
typedef SmartPointer< Self > Pointer;
typedef SmartPointer< const Self > ConstPointer;
/** Inherited typedef from the superclass. */
typedef typename Superclass::ValueType ValueType;
typedef typename Superclass::IndexType IndexType;
typedef typename Superclass::TimeStepType TimeStepType;
typedef typename Superclass::OutputImageType OutputImageType;
typedef typename Superclass::InputImageType InputImageType;
/** The function type which will calculate the curvature flow */
typedef CurvatureFlowFunction< OutputImageType > CurvatureFunctionType;
/** ValueType of the input binary image */
typedef typename TInputImage::ValueType BinaryValueType;
/** Method for creation through the object factory. */
itkNewMacro(Self);
/** Run-time type information (and related methods). */
itkTypeMacro(AntiAliasBinaryImageFilter, SparseFieldLevelSetImageFilter);
/** Get the upper and lower binary values in the input image. */
itkGetConstMacro(UpperBinaryValue, BinaryValueType);
itkGetConstMacro(LowerBinaryValue, BinaryValueType);
/** Set/Get the maximum number of iterations allowed for the solver. This
* prevents infinite loops if a solution "bounces". */
void SetMaximumIterations(unsigned int i)
{
itkWarningMacro("SetMaximumIterations is deprecated. Please use SetNumberOfIterations instead.");
this->SetNumberOfIterations(i);
}
unsigned int GetMaximumIterations()
{
itkWarningMacro("GetMaximumIterations is deprecated. Please use GetNumberOfIterations instead.");
return this->GetNumberOfIterations();
}
#ifdef ITK_USE_CONCEPT_CHECKING
// Begin concept checking
itkConceptMacro( DoubleConvertibleToOutputCheck,
( Concept::Convertible< double, typename TOutputImage::PixelType > ) );
itkConceptMacro( InputOStreamWritableCheck,
( Concept::OStreamWritable< typename TInputImage::PixelType > ) );
// End concept checking
#endif
protected:
AntiAliasBinaryImageFilter();
~AntiAliasBinaryImageFilter() ITK_OVERRIDE {}
virtual void PrintSelf(std::ostream & os, Indent indent) const ITK_OVERRIDE;
/** Overridden from the parent class to indroduce a constraint on
* surface flow under certain conditions. */
virtual ValueType CalculateUpdateValue(const IndexType & idx,
const TimeStepType & dt,
const ValueType & value,
const ValueType & change) ITK_OVERRIDE;
/** Overridden from ProcessObject to set certain values before starting the
* finite difference solver and then create an appropriate output */
void GenerateData() ITK_OVERRIDE;
private:
ITK_DISALLOW_COPY_AND_ASSIGN(AntiAliasBinaryImageFilter);
BinaryValueType m_UpperBinaryValue;
BinaryValueType m_LowerBinaryValue;
typename CurvatureFunctionType::Pointer m_CurvatureFunction;
const TInputImage *m_InputImage;
};
} // end namespace itk
#ifndef ITK_MANUAL_INSTANTIATION
#include "itkAntiAliasBinaryImageFilter.hxx"
#endif
#endif
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